steam generator tube integrity operational …the value that has been calculated is 0.028 gallon per...
Post on 26-Mar-2020
0 Views
Preview:
TRANSCRIPT
Steam Generator Tube Integrity Operational Assessment
Southern California Edison
San Onofre Nuclear Generating Station Unit 2 Cycle 10
Prepared
Reviewed
Approved
Richard A. Coe, Southern California Edison
Brian Woodman, APTECH Engineerinrg Services
I~chael I•. Short, Southern California Edison
CONTENTS
Section
EXECUTIVE SUMMARY
I INTRODUCTION
II CYCLE 10 INSPECTION SUMMARY
III CONDITION MONITORING
IV OPERATIONAL ASSESSMENT: STRUCTURAL MARGIN AND LEAKAGE EVALUATIONS
V SUMMARY AND CONCLUSIONS
VI REFERENCES
Appendix 1. STRUCTURAL INTEGRITY AND LEAK RATE MODELS
Appendix 2. ANALYSIS INPUT PARAMETERS
Appendix 3. PROBABILISTIC MODEL
Appendix 4. .EGGCRATE ODSCC
Appendix 5. EGGCRATE ID - PWSCC
Appendix 6. FREESPAN OD INDICATIONS
Appendix 7. TOP-OF-TUBESHEET CIRCUMFERENTIAL
Appendix 8. SLUDGE PILE OD AXIAL INDICATIONS
Appendix 9. WEAR
SOUTHERN CALIFORNIA EDISON Page 2
EXECUTIVE SUMMARY
An operational assessment of steam generator tubing in SONGS Unit 2 was
conducted following the cycle 10 refueling outage and is the subject of this
report. Operational Assessments are a requirement of the SONGS Steam
Generator Program (Reference 1).
The results of a comprehensive eddy current inspection prior to the beginning of
Cycle 9, mid-cycle 9 and at the refueling outage prior to Cycle 10 are the primary
inputs to this assessment. The scope and results of this inspection are
summarized in this report. Tube degradation at SONGS is prudently managed
with end of cycle inspections, in situ pressure testing, repairs, condition
monitoring and operational assessments. A mid Cycle 9 bobbin probe inspection
monitored the development of axial corrosion degradation at freespan and
eggcrate locations. Inspection results were used to check and update
projections for the following degradation mechanisms:
* Axial freespan ODSCC/IGA degradation
* Axial ODSCC/IGA at sludge pile locations
• Axiai ODSCC/IGA at eggcrate intersections
* Axial PWSCC at eggcrate intersections
* Circumferential ODSCC and PWSCC at TTS
* Wear
As in the past, a Monte Carlo computer model was used to simulate the
processes of crack initiation, crack growth and detection via eddy current
inspections over multiple cycles of operation. This allowed calculation of both
the conditional probability of tube burst at postulated steam line break conditions
and expected leak rates. Comparison of projected and observed degradation
severity provided a check of the simulation model.
SOUTHERN CALIFORNIA EDISON Page 3
Observed worst case degradation severity compared well with earlier projections
for all types of axial degradation.
The conditional probability of tube burst, given a postulated steam line break
after an additional 1.67 EFPY of operation in Cycle 10 is less than 0.01 for each
of the corrosion mechanisms. The arithmetical sum of the five mechanisms that
were considered in this analysis is 0.0019. The largest contributor is axial
ODSCC at eggcrate intersections, with a value of 0.0010. The figures of merit
per the NEI 97-06 (Reference 2) are 0.01 for any single mechanism and a total
of 0.05 for all mechanisms combined.
The 95/95 leak rate at postulated steam line break is also a result of this
analysis. The value that has been calculated is 0.028 gallon per minute (total)
at room temperature. The applicable criteria is 0.5 GPM for each steam
generator (1.0 GPM total).
The results of previous analyses (Reference 3 and 4) for axial and
circumferential corrosion degradation at the top of the tubesheet region plus the
present projections demonstrate that required structural and leak rate margins
will be maintained for the 1.67 EFPY planned Cycle 10 operating period.
SOUTHERN CALIFORNIA EDISON Page 4
INTRODUCTION
An operational assessment of steam generator tubing in SONGS Unit 2 was
conducted for the current Cycle 10 of operation. Six modes of corrosion
degradation were considered:
"* Axial freespan ODSCC/IGA degradation
"* Axial ODSCC/IGA at sludge pile locations
* Axial ODSCC/IGA at eggcrate intersections
* Axial PWSCC at eggcrate intersections
* Circumferential ODSCC and PWSCC at TTS
* Wear
In addition to a comprehensive examination at the beginning of the operating
cycle the results of a 100% mid cycle bobbin probe inspection after 0.8 EFPY of
operation in Cycle 9 were used to monitor the progression of axial degradation at
eggcrate and freespan locations and to check and update previous analyses for
the remainder of the Cycle 9 operating period. Comprehensive eddy current
examination at the prior to beginning of Cycle 10 was used to monitor for all
forms of tube degradation that were known active or deemed credible.
The onset of axial and circumferential corrosion degradation was observed in
SONGS-2 steam generator tubing after about 7.17 EFPY of operation.
Circumferential and axial degradation at the top of the tubesheet has been
observed using the RPC eddy current probe prior to Cycle 8, and the Plus Point
probe thereafter. Degradation is present on both inside and outside tube
diameters.
Tube wear is a known tube degradation mechanism in the SONGS Unit 2 steam
generators and accounts for a portion of tube repairs. Historically, wear has
been the subject of the majority of tube plugging in certain highly susceptible
SOUTHERN CALIFORNIA EDISON Page 5
areas near the center of the bundle and attributed to wear from batwings. These
episodes of wear-related tube repairs were early in the life of the unit. However,
the rate of new tube wear indications has trended upward in recent outages.
Axial corrosion degradation at freespan and eggcrate regions has been detected
with the bobbin probe. Eggcrate axial degradation has been observed on both
the inside and outside tube diameters, the ID degradation in these regions being
generally coincident with dented tubes. The presence of the eggcrate tube
supports, and to a greater degree, tube deformation in the eggcrate regions,
tends to make crack detection more difficult using the bobbin probe. The
simulation model employed in this work accounts for potential inspection
difficulties. Pulled tube test data confirmed that freespan axial OD corrosion
degradation was not particularly severe. In fact, near virgin tube burst pressures
were observed.. The mid cycle inspection in the previous operating cycle was to
investigate the state of axial PWSCC at some eggcrate locations.
Circumferential tube degradation has been detected at the top-of-tubesheet
(TTS) with rotating probe examinations. The indications origins are attributed to
the PWSCC at the ID of the tubes and ODSCC from the OD of the tubes. In
each case the indication is associated with the geometrical discontinuity at the
expansion transition.
An evaluation of the contribution of corrosion degradation to the conditional
probability of tube burst at postulated steam line break conditions and
determination of the upper bound leak rates expected during postulated accident
condition form the main objectives of the work described in this report. NEI 97
06 has established acceptable values for the conditional probability of tube burst
at SLB conditions as a measure of required structural margins. Accident
induced leak rates are calculated for comparison with the site-specific acceptable
value.
SOUTHERN CALIFORNIA EDISON Page 6
The basic calculational technique employed is one of simulating the processes of
crack initiation, crack growth and detection via eddy current inspection using
Monte Carlo methods. The Monte Carlo simulation model follows these
processes over multiple cycles of operation. This allows benchmarking of the
model by comparing calculated results for past inspections with actual
observations. The simulation model tracks both detected and undetected
populations of cracks and deals with actual crack sizes. When comparisons are
made between calculated results and eddy current observations, an eddy current
measurement error is applied to convert predicted real crack sizes to predicted
eddy current observations.
Actual degradation conditions in terms of number of cracks, real crack depths
and lengths can be calculated for any selected time period. Hence, the
conditional probability of burst at postulated steam line break conditions can be
computed for the operating time of interest. Leak rate during such a postulated
accident can be calculated from the simulated numbers and sizes of cracks.
Appendix 1 is a description the structural integrity and leak rate models including
of the methods of characterizing crack shapes and critical dimensions for
cracking. Also in Appendix 1 are explanations of burst pressure and leak rate
calculations. Appendix 2 describes input to the Monte Carlo simulation programs
and the simulation steps are discussed.
SOUTHERN CALIFORNIA EDISON Page 7
CYCLE 10 INSPECTION SUMMARY
Planned Inspection Scope
Table 1 summarizes the planned inspection program. Also, when indications by
the bobbin probe were non-quantifiable or distorted, the inspection program
included inspection with the Plus-Point Probe. Table 3 provides the list of
Nondestructive Examination (NDE) techniques utilized for each degradation
mechanism.
Inspection Scope Expansion
Table 2 summarizes significant inspection program scope expansion in response
to inspection results. The following explanatory details are provided for these
expansions.
It should be noted that only one apparently small axial indication was detected in
the sludge pile region near the top of the cold leg tubesheet. This was the first
time that this specific tube location had been examined with a rotating probe, so
the time that this indication may have been present cannot be ascertained. It
should be noted that an expansion with the plus point probe to 100% of these
locations in both steam generators did not detect further indications of this type.
In the course of this first-time 100% inspection of this location with the plus point
probe, 5 volumetric indications associated with eddy current indications of
foreign object presence were detected. These volumetric indications would not
have been detectable in previous bobbin probe inspections, due to their
proximity to the top-of-tubesheet. The volumetric indications, and associated
tubes with eddy current indications of foreign objects were removed from service
by installation of a "stabilizer" spanning the affected region, and plugging.
SOUTHERN CALIFORNIA EDISON Page 8
An axial crack indication at a dented eggcrate tube support was found within a
defined "buffer zone" (the uppermost hot leg eggcrate tube support) for a "critical
area for inspection." In response to this, the critical area was re-defined to
include this buffer zone. A new buffer zone was defined as all dented tube
supports at the next highest elevation (the hot leg diagonal bar support).
SOUTHERN CALIFORNIA EDISON Page 9
TABLE I Summary of the Planned Inspection Program for the Unit 2 Cycle 10 Refueling
Outage
Steam Steam Number of Tubes/Percentage of Tubes Generator Generator
E-088 E-089
Full length of tube with the bobbin probe 8714/100% 8692 /100%
Hot leg expansion transition at the top-of-tubesheet with the Plus 8714 / 100% 8692/100% Point Probe
Cold leg expansion transition at the top-of-tubesheet with the Plus 1926 / 22% 1900 /21% Point Probe
Tight radius U-bend regions Rows 1, 2 and 3 with the Plus-Point 184/100% 185/100% Probe
Plus-Point Probe examination of all hot leg eggcrate supports with 3070 / 100% 2260 /100% dents > or equal to 2 volts and dings in that region > or equal to 5 volts
Plus-Point Probe examination of all tube support intersections with 236 / NA 270 / NA quantified wear indications by the bobbin probe
Rotating pancake coil probe exam of INCONEL 690 tube plugs that 225/40% 224/40% had been previously installed in the hot leg using a "roll" process
TABLE 2 Summary of Significant Scope Expansion for the Unit 2 Cycle 10 Refueling Outage
Steam Steam Number of Tubes/Percentage of Tubes Generator Generator
E-088 E-089
Cold leg expansion transition at the top-of-tubesheet with the Plus- 6788 1 100% 6792/100% Point Probe
Plus-Point Probe examination of all hot leg diagonal bar tube 127 / NA 42 / NA supports with dents > or equal to 2 volts
SOUTHERN CALIFORNIA EDISON Page 10
TABLE 3 - List of Nondestructive Examination (NDE) Techniques Utilized for Detection and Characterization of Each Degradation Mechanism During the Unit 2 Cycle 10 Refueling Outage
ORIENTATIONILOCATION DETECT CHAR'ZE
Axially oriented ID (initiated on the inside-diameter of the Bobbin Plus Point
tubing wall) indications at tube support locations
Plus Plus Point Point (Note 1)
2 Axially oriented OD (initiated on the outside-diameter of Bobbin Plus Point the tubing wall) indications at tube support locations
Plus Plus Point Point (Note 1)
3 Axially oriented OD indications not associated with a Bobbin Plus Point tube support (freespan)
4 Circumferentially oriented ID indications near the Plus Plus Point expansion transition at the top of the hot leg tubesheet Point
5 Circumferentially oriented OD indications near the Plus Plus Point expansion transition at the top of the hot leg tubesheet Point
6 Axially oriented indications in the sludge pile region near Plus Plus Point the top of the hot leg tubesheet Point
7 Axially oriented OD indications in the sludge pile region Plus Plus Point near the top of the cold leg tubesheet Point
8 Axially oriented ID indications near the expansion Plus Plus Point transition at the top of the hot leg tubesheet Point
9 Axially oriented indications below the inlet top-of- Bobbin Plus Point tubesheet
10 Indications of wear at tube support locations Bobbin Plus Point
11 Volumetric indications associated with the presence of a Bobbin Plus Point foreign object
Plus Point Plus Point near the "TI-S
12 Circumferentially or axially oriented indications within Pancake Pancake INCONEL 690 tube plugs that had been previously Coil Coil installed in the hot leg using a "roll" process
Note 1: Plus Point technique is used at Dents > or = to 2 volts, at or below the Diagonal Bar on the Hot leg side (DBH)
SOUTHERN CALIFORNIA EDISON Page 11
INSPECTION RESULTS
Indications of degradation detected during the examination were dispositioned by
plugging and in some cases tube sleeving was used. Also, certain of the larger
indications was pressure tested in situ to determine if the tube degradation was
such that prescribed margins against burst were violated. Table 4 lists the tubes
that were repaired and the reasons. Table 5 lists the tubes that were pressure
tested in situ. The results of the in situ pressure tests were favorable, that is, no
leakage was noted and no tubes exhibited burst.
SOUTHERN CALIFORNIA EDISON Page 12
TABLE 4 Numbers of Tubes Repaired and Active Degradation Mechanisms Found
During the Unit 2 Cycle 10 Refueling Outage
Indication Orientation/Location 088 089
1 Tubes with axially oriented ID (initiated on the inside-diameter of the tubing wall) 4 3 indications at tube support locations
2 Tubes with axially oriented OD (initiated on the outside-diameter of the tubing wall) 11 10 indications at tube support locations
3 Tubes with axially oriented OD indications not associated with a tube support 8 7 (freespan)
4 Tubes with circumferentially oriented ID indications near the expansion transition at 46 15 the top of the hot leg tubesheet I
5 Tubes with circumferentially oriented OD indications near the expansion transition 12 19 at the top of the hot leg tubesheet
6 Tubes with axially oriented OD indications in the sludge pile region near the top of 14 10 the hot leg tubesheet
7 Tubes with axially oriented OD indications in the sludge pile region near the top of 1 0 the cold leg tubesheet
8 Tubes with axially oriented ID indications near the expansion transition at the top of 19 6 the hot leg tubesheet
9 Tubes with axially oriented ID indications below the inlet top-of-tubesheet 3 7
10 Tubes with indications of wear at tube support locations 18 12
11 Tubes with volumetric indications associated with the presence of a foreign object 0 5
12 Tubes that were preventatively plugging based on the presence of a foreign object 0 8 (notan active degradation mechanism)
13 Miscellaneous preventative plugging (not an active degradation mechanism) 1 0
Total 137 102
SOUTHERN CALIFORNIA EDISON Page 13
TABLE 5 - Summary of Results of In-Situ Pressure and Leak Testing for the Unit 2 Cycle 10 Refueling Outage Steam Generator E-088
TUBE AND EDDY CURRENT INFORMATION IN-SITU TEST RESULTS REGION TUBE INFORMATION PLUS POINT DATA SELECTION GPM @ GPM @ GPM @ MAXIMUM
ROW COL LOCATION LENGTH VOLTS PDA EST. ORIENTATION CRITERIA NOPD MSLB POST MSLB PRESSURE EGGCRATE 21 121 04H - 0.05 0.22 1.01 NA 65 ID Axial L 0 0 NA 4712
04H + 0.44 0.22 0.83 NA 51 ID Axial L 0 0 NA 4712 62 76 06H + 0.65 0.27 1.08 NA 69 ID Axial L 0 0 NA 4712
06H + 0.15 0.18 0.84 NA 72 ID Axial L 0 0 NA 4712 TUBESHEET 29 49 TSH + 0.01 0.81 1.55 16 82 ID Circ L 0 0 NA 5254
Steam Generator E-089 TUBE AND EDDY CURRENT INFORMATION IN-SITU TEST RESULTS
REGION TUBE INFORMATION PLUS POINT DATA SELECTION GPM @ GPM @ GPM @ MAXIMUM ROW COL LOCATION LENGTH VOLTS PDA EST. ORIENTATION CRITERIA NOPD MSLB POST MSLB PRESSURE
EGGCRATE 65 55 08H + 0.28 0.86 1.76 NA 66 ID Axial P 0 0 NA 4712 114 42 06H + 0.29 0.46 0.23 NA 89 OD Axial P 0 0 NA 4712
FREESPAN 114 42 06H + 2.44 1.10 0.36 NA NA OD Axial P&L 0 0 NA 4712 TUBESHEET 62 88 TSH + 0.30 0.47 0.56 NA 54 OD Axial P & L 0 0 NA 5254
r TSH + 0.10 0.86 0.58 23.9 57 OD Circ P 0 0 NA 5254 12 2 TSC + 0.01 2.99 1.72 NA NA OD Vol P 0 0 NA 4712 14 2 TSC + 0.12 1.75 2.09 NA NA OD Vol P 0 0 NA 4712
NOTES: The SELECTION CRITERIA column indicates the EPRI In Situ Testing Guidelines' criteria that prompted selection. P = Pressure testing for structural integrity criteria L = Testing for criteria for postulation of accident-induced leakage integrity GPM = Gallons per Minute NOPD = Normal Operation Pressure Differential MSLB = Main Steam Line Break Pressure Differential NA = Not Applicable OD = Degradation initiated on the outside diameter of the tubing ID = Degradation initiated on the inside diameter of the tubing CIRC = Circumferential PDA = Percent degraded area VOL = Volumetric EST. = Estimated maximum per-cent throughwall depth of the degradation
The test pressure that correlates to 3 times NOPD is 4712 psi for axial indications and 5254 psi for circumferential indications.
SOUTHERN CALIFORNIA EDISON Page 14
CONDITION MONITORING
The as-found condition of the steam generator tubes is described in the preceding
section. The comprehensive nature of the inspection scope and the methods
provide assurance that indications of steam generator tube degradation are found.
The inspection met or exceeded prevailing industry standards and good practices.
The as left condition of the steam generator tubes is defined by the plugging and
repair scope is stated in the previous section. All crack-like indications were
plugged or repaired by tube sleeving. All wear indications exceeding the technical
specification limit of 44% through-wall were plugged. As a conservative and
preventive tactic - all indications of wear that exceeded 30% through wall were
preventively plugged.
IN SITU PRESSURE TESTING
Indications of tubing degradation were screened against the performance
criteria to determine candidates for in situ pressure and in situ leak testing.
At the end of the operating period there was no known primary-to-secondary
leakage attributable to steam generator tube degradation.
The method of screening the NDE data for in situ test candidates was that
stated in the Draft EPRI TR-107620 "Steam Generator In Situ Pressure Test
Guidelines" dated October 1998 (Reference 5). Specific numerical value
criteria for screening indications have been calculated that are directly
applicable to the SONGS steam generators. These criteria are the result of
work that was performed by the ABB-CE Owners Group (Reference 6).
All degradation modes were included in the screening. Linear indications in
the circumferential and the axial directions originating at both the inside and
SOUTHERN CALIFORNIA EDISON Page 15
outside surfaces of the tube were the majority of the effort. Volumetric
indications and indications of wear were also separate populations that were
considered. Additionally, since SONGS has pressure tested 56 tubes in
previous outages for some of the types of indications stated above, SONGS
experience was also considered in the selection of candidates of tubes for
testing.
In situ testing at SONGS has and can be performed on full length tubes as
well as on defect specific areas. Bladders may be available for use on tubes
when leakage is incurred that exceeds the capacity of the test pump. In
each case appropriate correction factors are used in determination of the test
pressures that are needed to satisfy the objectives of the in situ test.
Correction factors are also applied to account for the effect of test
temperature on material properties.
Since the majority of the indications of degradation that have been screened
have been linear indications and since each screening has inherent
differences in screening methods and/or screening criteria, a brief description
of the method used as SONGS follows:
Axial OD
Pressure Test Screening
All OD axial indications at the tubesheet, sludge region and eggcrates
were depth-sized by the sizing analyst. OD axial indications occurring
in the free span were not depth-sized. All OD axial indications,
excluding indications within the free span, were evaluated based on
structural length. If an indication was less than the structural length,
the selection process was terminated, and pressure testing was not
required. However, if the length exceeded the structural length, the
depth was used to screen for pressure test candidates.
SOUTHERN CALIFORNIA EDISON Page 16
Freespan OD indications were compared to previous tube pulls, lab
analysis and previous in situ pressure test results to determine if the
indications were relevant for consideration for in situ pressure testing.
Leak Test Screening
Axial OD indications were screened based on a maximum depth
threshold for leakage. All indications exceeding this threshold were
evaluated on an individual basis.
Axial ID
Pressure Test Screening
All ID axial indications at the tubesheet transition and eggcrate tube
supports were depth-sized by the sizing analyst. These indications
were evaluated using the ID axial criteria. Because of the
strengthening effect of the tubesheet, ID axial indications occurring
within the tubesheet were not depth-sized.
Leak Test Screening
Axial ID indications were screened based on a maximum depth
threshold for leakage. All indications exceeding this threshold were
evaluated on an individual basis.
Circumferential OD
Pressure Test Screening
All OD circumferential indications occurring at the tubesheet were
depth-sized. In addition, Percent Degraded Areas (PDAs) were
determined for all OD circumferential indications based on the product
SOUTHERN CALIFORNIA EDISON Page 17
of maximum depth and length, which was divided (conservatively) by
the ID circumference. A PDA threshold was used to determine
whether or not an indication was a candidate for pressure testing.
The Flaw Length Degraded Area (FLDA) was not determined for the
majority of OD circumferential indications. But, for a few over
conservative PDAs, the Draw Program was used to find FLDA and
determine PDA for two OD circumferential indications. The ratio of
the crack angle to 360 degrees multiplied by the FLDA resulted in a
lower, more accurate PDA calculations for these two indications.
Including the two OD circumferential indications, which were depth
sized using the Draw Program, no OD circumferential indication
required pressure testing based on the defined PDA threshold.
Leak Test Screening
OD circumferential indications were evaluated on an individual basis as
candidates for leakage testing.
Circumferential ID
Pressure Test Screening
All ID circumferential indications occurring at the tubesheet were
depth-sized using the EPRI appendix H amplitude method. Further,
Percent Degraded Areas (PDAs) were determined by two methods.
First, given the goal of utilizing the Draw Program to determine FLDA
and Crack Angle (CA), the sizing analyst characterized all ID
circumferential indications that were not associated with software
limiting geometric conditions at the axial elevation of the
circumferential indication. PDA was determined by multiplying FLDA
SOUTHERN CALIFORNIA EDISON Page 18
(output of the "Draw" program) by the ratio of the crack angle to 360
degrees.
Second, due to the geometric limitations near some of the ID
circumferential indications, the sizing analyst had to depth-size using
an ID degree curve from the Eddynet® Window. PDA was determined
by dividing the product of maximum depth and Resolution Plus Point
Length by the ID circumference of the tube.
Leak Test Screening
ID circumferential indications were evaluated on an individual basis as
candidates for leakage testing.
Volumetric indications such as "Small volume indications" were also
evaluated for in situ pressure testing. Volumetric candidates were
screened based on the axial and circumferential extent. These
indications were not depth-sized.
In Situ Pressure Test Results
The tubes that were selected for in situ testing, the test pressure and the
results are Table 5. In all cases the desired pressures were achieved. No
leakage and no failures were experienced in the testing.
SOUTHERN CALIFORNIA EDISON Page 19
OPERATIONAL ASSESSMENT: STRUCTURAL MARGIN AND
LEAKAGE EVALUATION
Monte Carlo simulation models were used to project the progress of a corrosion
degradation of steam generator tubing in SONGS Unit 2. Six degradation
mechanisms were considered in total. The severity of PWSCC at a limited
number of eggcrate intersections indicated that the prudent course of action was
to inspect and monitor the progression of axial degradation at eggcrate locations
approximately midway through Cycle 9. This inspection was performed and the
results are also the subject of an earlier report (Reference 4). Freespan and
eggcrate ODSCC/IGA indications were naturally encountered in the 100%
bobbin probe mid-cycle exam. These indications as well as PWSCC indications
were removed from service.
When prudent, but not unduly conservative, choices are made relative to crack
growth rate distributions and POD curves, projected and observed numbers of
indications at both Cycle 9, the Cycle 9 mid cycle inspection and the Cycle 10
inspection are in good agreement.
The results of the structural margin and leakage evaluation are shown in the
following chart, Table 6.
SOUTHERN CALIFORNIA EDISON Page 20
TABLE 6 SUMMARY OF STRUCTURAL MARGIN AND PROJECTED SLB LEAK RATES
PROJECTED FOR 13.33 EFPY (EOC 10)
Degradation Conditional Conditional 95195 Leak Rate at Mechanism Probability of Burst Probability of Burst Postulated SLB
at Postulated SLB at 3xNODP (GPM at Room (95% Confidence (50% Confidence Temperature)
Level) Level)
Axial ODSCC at <0.0001 0 0 Eggcrate Intersections
Axial PWSCC at 0.0010 0.0191 0.011 Eggcrate Intersections
Freespan Axial <0.0001 0 0 ODSCC
Circumferential ODSCC/PWSCC at 0.0005 0.0024 0.017 Expansion Transitions
Sludge Pile Axial <0.0001 0 0
Wear <0.0001 0 0
Arithmetic Total 0.0019 0.0215 0.028
0.0015 0.0191 Boolyan Sum Max Value
Acceptance <0.05 Total None <0.5 gpm Criteria <0.01 per
mechanism
SOUTHERN CALIFORNIA EDISON Page 21
SUMMARY AND CONCLUSIONS
A probabilistic operational assessment of steam generator tubing in SONGS Unit
2 was conducted for Cycle 10 of operation following a comprehensive eddy
current inspection at 11.7 EFPY of operation at the end of cycle 9. A mid cycle
bobbin probe inspection monitored the development of axial corrosion
degradation at freespan and eggcrate locations. Inspection results were used to
check and update projections for the following degradation mechanisms:
"* Axial freespan ODSCC/IGA degradation
"* Axial ODSCC/IGA at sludge pile locations
* Axial ODSCC/IGA at eggcrate intersections
* Axial PWSCC at eggcrate intersections
* Circumferential ODSCC and PWSCC at TTS
* Wear
Monte Carlo simulation models were used to project the progress of corrosion
degradation of steam generator tubing in SONGS Unit 2. Corrosion degradation
was conservatively represented as planar cracking. The processes of crack
initiation, crack growth and detection of cracking by eddy current inspections
were simulated for multiple cycles of operation. Thus the severity of corrosion
degradation was projected for operating cycles and times of interest. Both
detected and undetected crack populations are included. Burst and leak rate
calculations are based on the total crack population. The simulation model is
benchmarked by comparing simulation results with actual eddy current
inspection results, notable in situ test results, and pulled tube test data.
Projected levels of corrosion degradation severity allowed calculations of the
conditional probability of tube burst and an upper bound accident induced leak
rate. At EOC 10, at 13.33 EFPY of operation, the conditional probability of tube SOUTHERN CALIFORNIA EDISON Page 22
burst, given a postulated steam line break event, is less much than 0.01 for each
of the six corrosion mechanisms. The arithmetical total conditional probability of
tube burst is 0.0019, which is considerably less than the 0.05 criteria from NEI
97-06. The largest contributor to the conditional probability of tube burst is axial
PWSCC at eggcrate intersections. The contribution from circumferential
degradation at the top of the tubesheet is comparable. The projected 95/95 leak
rate total, for both steam generators at postulated SLB conditions is 0.028 gpm
at room temperature which compares favorably with the acceptance criteria of
0.5 gpm in each steam generator. Most of this total is associated with top of the
tubesheet circumferential corrosion degradation.
SOUTHERN CALIFORNIA EDISON Page 23
REFERENCES
1. SO123-SG-1, San Onofre Nuclear Generating Station, "Steam Generator Program", dated December 1998
2. NEI 97-06, Revision 0, "Steam Generator Program Guidelines", dated December 1997.
3. Begley, C.J., Woodman, B.W., and Begley, J.A., "A Probabilistic Operational Assessment of Steam Generator Tube Degradation at Songs Unit 2 for Cycle 9, APTECH Report AES 97043057-1-1, Rev. 2, September, 1997.
4. Begley, C.J and Begley, J. A., "An Updated Probabilistic Operational Assessment For Songs Unit 2, Second Mid Cycle Operating Period, Cycle 9" APTECH Report AES 98033327-1-1, Rev. 0, April, 1998.
5. EPRI Draft Report TR-107620 "Steam Generator In Situ Pressure Test Guidelines; October 1998
6. CE NPSD-1 005-P ABB/CEOG "Steam Generator Tube In Situ Pressure Test Guidelines CEOG Task 844"; June 1995
7. Cochet, B., "Assessment of the Integrity of Steam Generator Tubes - Burst Test Results - Validation of Rupture Criteria (FRAMATOME DATA)," Palo Alto, CA, Electric Power Research Institute, NP-6865-L, Vol. 1, June, 1991.
8. "PICEP: Pipe Crack Evaluation Program (Revision 1)", Electric Power Research Institute, December, 1987, NP-3596-SR, Revision 1.
9. Begley, J.A., "Leak Rate Calculations for Axial Cracks in Steam Generator Tubing," APTECH Calculation AES-C-2797-2, dated April, 1997.
10. "PWR Steam Generator Tube Repair Limits - Technical Support Document for Outside Diameter Stress Corrosion Cracking at Tube Support Plates", EPRI Report, TR-00407 Rev. 1, August, 1993.
11.Zahoor, A., "Ductile Fracture Handbook", EPRI Report, NP.6301-D, RP 175769, June, 1989.
12."Depth Based Structured Analysis Methods for SG Circumferential Indications", EPRI Report, EPRI TR-107197-PI, Interim Report, November, 1997.
13."SLB Leak Rate and Tube Burst Probability Analysis Methods for ODSCC at TSP Intersections," Westinghouse Non-Proprietary Class 3 Report, WCAP14277 Revision 1, December, 1996.
SOUTHERN CALIFORNIA EDISON Page 24
Appendix 1
STRUCTURAL INTEGRITY AND LEAK RATE MODELS
Burst strength and leak rate calculations for tubes exhibiting axial corrosion
degradation are based upon idealized crack profiles. Axial degradation is
modeled as planar cracking. The planar crack assumption is conservative for
use in burst and leak rate calculations. The following paragraphs describe
idealized morphologies for axial cracks and corresponding burst and leak rate
equations. Note that the pattern of throughwall crack development in the leak
rate model has been modified compared to earlier reports. This modification
makes calculated leak rates more conservative.
Idealized Axial Crack Profiles
From the perspective of tube burst strength and leak rate calculations, each axial
corrosion indication is idealized as a single planar crack. This is conservative in
that the strengthening and leak limiting effects of ligaments between crack
segments in physical crack arrays are neglected. In addition, the physical depth
profile, which typically varies in a non-uniform fashion over the length of the
crack, is modeled as a simplified ideal profile for burst and leak calculations.
Figure Al.1 illustrates the idealized crack profiles used for burst and leak
calculations, compared to the corresponding physical depth profile as measured
during a pulled-tube destructive examination. The idealized burst profile
represents the portion of the physical profile that is structurally significant in
computing burst pressure. The structurally significant dimensions are
determined using the Structural Minimum Method, as follows. The physical
profile is discretized over its length using a reasonable number of segments,
typically between 20 and 50. For each contiguous portion of the crack (that is,
for each potential structurally significant length segment), a corresponding depth
is computed by equating the areas under the physical and ideal profiles. Each
SOUTHERN CALIFORNIA EDISON Page 25
length and depth pair is then tested using the Framatome burst equation
(Reference 7, described below) to find the dimensions that minimize the
computed burst pressure. The length and depth that minimize the burst pressure
represent the structurally significant dimensions, and hence define the idealized
burst profile. It is essential to note that historical measurements have shown that
structurally significant length of a crack to be reasonably estimated by the portion
of a physical crack length detected by a rotating pancake coil eddy current
probe. The axial length detected by the Plus Point eddy current probe is a
conservative estimate of the actual structurally significant crack length.
The idealized leak profile length is identical to the structurally significant length
computed for the burst profile. The tent-shaped leak profile is then determined
by equating the maximum depth penetration for both physical and ideal profiles,
and by again balancing the areas under the respective profiles over the
structural length. The profile form factor, F, is defined to be the ratio of the
maximum depth, dx, to the structurally significant depth, dt. The distribution
characteristics of this form factor are based on pulled tube destructive
examination data. See Figure A1.2.
Crack growth over time is assumed to occur primarily in the depth direction. The
structural length for both burst and leak profiles is considered to be constant in
time. Compared to previous calculations, an element of conservatism has been
added to the leak rate model. In contrast to the earlier leak model, the form
factor is assumed to remain constant only until wall penetration occurs. Then, as
the crack propagates throughwall, as shown in Figure A1.3, the inclined sides of
the crack rotate outward until a limiting throughwall length equal to the structural
length is reached. The incremental area of crack advance per unit time created
by the rotating crack sides is equal to the specified average depth crack growth
rate. The length of the throughwall segment, Ljeak, is then defined by the
geometry of the idealized profile to be:
SOUTHERN CALIFORNIA EDISON Page 26
t
Ll =4 F t-
F
Axial Crack Burst Pressure Calculation
Given the structurally significant length and depth dimensions, the burst pressure
for an axially degraded tube is computed via the Framatome (Cochet et. al.)
partial throughwall burst equation:
0.58s 1 It
RL L +2t]
where P is the estimated burst pressure, S the sum of the yield and ultimate
tensile strength of the tube material, t the tube thickness, Ri the inner radius of
the tube, L the characteristic degradation length, and d the characteristic
degradation depth. The Framatome equation, when used with the structurally
significant dimensions (Lt and d,), produces consistently conservative burst
pressure estimates compared to measured burst data, as shown in Figure A1.4.
It is an excellent lower bound to an extensive set of pulled tube burst test data.
Axial Crack Leak Rate Calculation
As described in Reference 8, Version 3.0 of the PICEP two-phase flow algorithm
was used to compute flow rates through cracks as a function of pressure
differential (p), temperature (7), crack opening area (A), and total throughwall
crack length (L). Friction effects and crack surface roughness were included in
the model. Steam line break, room temperature, and normal operating condition
leak rates calculated by PICEP were fitted to regression equations. The PICEP
based leak rate regression equation for steam line break conditions is given as:
Q = {a + b exp [c (AIL)0. 5' + d (AIL)]) A p 1 3 ,
SOUTHERN CALIFORNIA EDISON Page 27
where a-d are regression coefficients as determined by an analysis of PICEP
results. The leak rate Q is expressed in terms of gallons per minute at room
temperature (700F). To convert to gallons per minute at any other temperature,
the calculated Q is multiplied by the ratio of the specific volume of water at
temperature (7) to the specific volume of water at 700F. The pressure, p, is in
units of psi, A is in inches2 and L (equivalently Lleak as defined above) is in inches.
The crack opening area is calculated using a twice-iterative plastic zone
correction to adjust the linear elastic solution for plasticity effects. Further details
of the PICEP regression equations and the crack opening area derivation can be
found in References 8, 9, 10 and 11.
A check of the validity of the leak rate equations is provided by a comparison of
calculated leak rates versus measured leak rates listed in Reference 10.
Measured leak rates at typical normal operating steam generator conditions are
available for axial fatigue cracks in steam generator tubing and axial stress
corrosion cracks in steam generator tubing. Leak rates through stress corrosion
cracks are less than those through fatigue cracks of the same length because of
the more torturous cracking in stress corrosion samples. A good conservative
leak rate calculation methodology is considered to be one which is a closer
match to leak rate results from fatigue cracks rather than stress corrosion cracks.
Figure A1.5 shows that this criteria is met by the chosen methodology.
Calculated leak rates, illustrated by the dotted lines, serve as a good bound to
data from stress corrosion cracked samples of the same tubing dimensions. The
calculated leak rates are just below the measured data for fatigue cracked
samples.
SOUTHERN CALIFORNIA EDISON Page 28
40
3DI
2D
10 Lst 0' 00 02 04 06 08 1o 12 1.4 16
crack length
(a)
•~drnax 4D.4
10--- Lst
00 02 04 06 08 tol 12 1. 1.6
crack length
(b)
Figure A1.1 Idealized Crack Profiles for Burst (a) and Leakage (b)
SOUTHERN CALIFORNIA EDISON Page 29
Figure A1.2 Maximum Depth vs. Structurally Significant Depth - Pulled
100 Tube Data
90 - 1*.
I I 80 - /! ,
70 1 I
60 I~* F
CLI
I. * *1- __ _ I
5o "501* t E I E 40 -* 1r I
30 *.1 _ _ _ _ I, I
20 I
10 _____
00 10 20 30 40 50 60 70 80 90 100
Structural Depth, %TW
SOUTHERN CALIFORNIA EDISON Page 30
Figure A1.3 Idealized Leakage Crack Profile After Throughwall Penetration
L leak
tr
SOUTHERN CALIFORNIA EDISON Page 31
]
I.=
I..
0.u
LU
14000
12000
10000
8000
6000
4000
2000
00 2000 4000 6000 8000 10000 12000 14000
Measured Burst Pressure, psi
Figure A1.4 Burst Pressure
SOUTHERN CALIFORNIA EDISON Page 32
100
10
i Ao
I j JI o°
0.1
O _ _ _ _ _ _ _ _ I -__ _ _ _ _ _ _ _
0• i 0.01 •,• I O I _
""I. 0 1 I ,,°I I , I
0.01I ! i
0.00 1 -w'0 -WFTGU RCKDDT .... ". ..0.875" OD BY 0.050" WALL
"0.750" OD BY 0.043"W
oCEGBSCC .0.0"01 CEGB FATIGUE CRACKED DATA
0.0..0085"O1BY0.50 WL
0.1 CRACK LENGTH, INCHES
Figure A1.5 Calculated and Measured Leak Rates for Axial Cracks in Alloy
600 Tubing at Normal Operating Conditions
SOUTHERN CALIFORNIA EDISON Page 33
Circumferential Crack Idealized Morphologies
The parameter chosen to define the severity of circumferential degradation is the
percentage of the tube crossectional area, which suffers corrosion degradation.
Hence the term PDA or percent degraded area. As with axial degradation, a
planar crack morphology is the idealized representation of circumferential
degradation. For burst calculations it is practical to consider the worst case
crack morphology for a given value of PDA. Here a single dominant crack is
assumed and all of the degraded area is assigned to a single throughwall crack.
This assumption is conservative but not unreasonable for burst calculations".
For leak rate calculations, always assuming this single throughwall crack
geometry is grossly unreasonable. If this absolute worst case morphology is
always assumed, then cracks which do not change the burst pressure from its
undegraded value would be assumed to leak at more than 0.5 gpm at postulated
steam line break conditions. Clearly a more practical approach to the
conservative estimation of leaking crack lengths and leak rates is needed.
A reasonable yet conservative estimation of end of cycle circumferential leaking
crack lengths must be based on observed crack profiles. A thorough study of
circumferential crack profiles Was conducted as part of the EPRI/ANO
Circumferential Crack Program dealing with circumferential degradation at
expansion transitions. These results are summarized as follows. The
morphology of circumferential degradation shows a substantial variation but it is
remarkably consistent irrespective of ID or OD initiation or expansion transition
type. The general picture is one of multiple crack initiation sites distributed
around the tube circumference. The axial extent of this band of circumferential
initiation sites ranges from 0 to 0.2 inches. This initiation morphology gives rise
to a latter morphology of deep crack segments against a background of relatively
shallow degradation.
SOUTHERN CALIFORNIA EDISON Page 34
A deep crack segment is considered to be a region where the local depth is more
than twice the background depth. On this basis, the number of deep crack
segments per degraded tube circumference was found to range between 0 to 4
from pulled tube examinations. 'A roughly uniform depth profile is obtained when
the number of deep crack segments is either 0 or 4. Typically, 1, 2 or 3 deep
crack segments are encountered as a degraded tube circumference is traversed.
The probability of 1, 2 or 3 deep crack segments is about the same: 0.32. The
probability of 0 or 4 deep cracks is taken to be 0.02 based on pulled tube data.
The circumferential extent of an individual deep crack segment varies from 40" to
360'. The distribution of individual deep crack segment lengths can be estimated
from pulled tube data and from field eddy current inspection results. This has
been done in the EPRI/ANO program. One check of the idealized
circumferential crack morphology description is to predict the distribution of total
arc lengths of circumferential degradation detected by pancake eddy current
inspections from the frequency of occurrence of deep crack segments and the
selected distribution of individual deep crack segments. As shown in Reference
12, predictions and measurements are in very good agreement. The idealized
circumferential degradation morphology, together with the probability of
occurrence of the number of deep crack segments and the distribution of deep
crack segment lengths, provide for reasonable yet conservative projections of
through-wall leaking crack lengths needed for leak rate calculations. The leak
rate calculations are discussed in a following section.
Circumferential Crack Burst Pressure Calculation
Data in the literature and testing conducted as part of the EPRI/ANO
Circumferential Crack Program shows that the burst pressure of tubing with
circumferential degradation is bounded by the single planar, throughwall crack
idealization. Further, in the region of interest hear steam line break pressure
differentials, the burst mode is dominated by tensile overload of the net
SOUTHERN CALIFORNIA EDISON Page 35
remaining section. In this region of extensive degradation, a lower bound
representation of the burst pressure is given by equating the average net section
axial stress to the material flow strength. The burst pressure for a tube with
outside diameter circumferential degradation, in the tensile burst mode region, is
then given as:
P0 = ((Ro2 - Ri2) / Ri2) (1-PDA)(S/2)
where P0 is the burst pressure, PDA is percent degraded area, S is the sum of
yield and ultimate strength at the temperature of interest, Ro is the tube outer
radius and R, is the tube inner radius. For inside diameter circumferential
cracking, the pressure on the crack face itself reduces the burst pressure and
dictates a correction factor in the burst pressure equation:
Pi = Po Ri2/(Ri2 + R02- Ri2) PDA),
where P, is the burst pressure corrected for ID degradation.
Circumferential Crack Leak Rate Calculations
The PICEP based formula presented in an earlier section can be used for either
axial or circumferential cracks if the appropriate expression for crack opening
area is used. For circumferential cracks, a formulation for crack opening area
from the Ductile Fracture Handbook" was used. A plastic zone correction to the
crack length was applied. Calculated crack opening areas matched actual
measurements made as part of the EPRI/ANO Circumferential Crack Program.
Hence crack opening area calculations are well benchmarked. Since the basic
conservative nature of the PICEP based leak rate equation is demonstrated by
the comparison of measured and calculated leak rates presented in section an
earlier section, the lone remaining input for circumferential cracking is the
projected end of cycle leaking crack lengths. This projection is developed from
SOUTHERN CALIFORNIA EDISON Page 36
calculations of the end of cycle PDA values. The preceding description of
circumferential crack morphology provides a picture of deep crack segments
against a shallower background of corrosion degradation. Leakage will develop
as these deep crack segments penetrate the wall thickness. A conservative
estimate of leaking crack lengths is provided by assuming that all of the
degraded area is assigned to deep crack segments in a sequence that produces
the largest total leak rate. In most cases, a shallower background level of
degradation exists but, in order to be conservative for leak rate calculations, all
degradation is assigned to deep crack segments until all segments in a given
tube are driven throughwall.
A crack morphology simulator program has been written using the data of the
previous section. A PDA value for a tube is selected, the number of deep crack
segments is sampled according to the observed frequency of occurrence and
deep crack segment lengths are sampled from an appropriate Weibul
distribution. The program then apportions the PDA to the deep crack segments
to determine if wall penetration is possible. If wall penetration is possible, the
program determines, with the given number and lengths of deep crack
segments, the largest leak rate, which can be produced.
SOUTHERN CALIFORNIA EDISON Page 37
Appendix 2
ANALYSIS INPUT PARAMETERS
A number of input parameters are needed for the Monte Carlo simulation model.
A range of material properties is considered rather than a lower bound strength
value. Hence the distribution of tensile properties of the steam generator tubing
is needed. The distribution of structurally significant axial crack lengths is
equated to the distribution of measured lengths as found by the RPC eddy
current probe. Thus a sampling distribution of axial crack lengths is needed.
The simulation model conducts virtual inspections. This requires knowledge of
the probability of detection of degradation as a function of degradation severity
for the various eddy current probes that are used. Since degradation growth is
simulated, distributions of crack growth rates for both axial and circumferential
degradation are required.
Inputs to the are constant throughout with different mechanisms are:
* Tube dimensions
* Mechanical Properties for the tube material
S95/95 Strength at temperature - Maximum, minimum, mean and
standard deviation
= Young's Modulus
* Number of tubes at risk
* Number of sites per tube at risk
* Pressure differential for Main Steam Line Break
* Pressure differential for Normal, Steady State operation
* Primary to Secondary Leak Limit
Inputs to the calculational program that varied with different mechanisms
are:
SOUTHERN CALIFORNIA EDISON Page 38
* Inspection Cycles ePOD
= Intercepts
= Slopes
* Growth
= Logarithm Mean (Ln)
=> Maximum
* Standard Deviation
= Fraction Zero
"* Crack Initiation Parameters
= Slope
= Scale
=> Set Back
"* Sizing Error
= Mean
SStandard Deviation
SMaximum
Tubing Mechanical Properties
Figure A2.1 shows a histogram of tube strength for both steam generators at
SONGS Unit 2. An adjustment has been made to correct for operating
temperature. A normal distribution was fitted to the data of Figure A2.1 for
application in the simulation model. This distribution was truncated at the
measured extremes of the tensile property database.
Degradation Length Distribution
During the recent mid cycle eddy current inspection at SONGS Unit 2, crack
length measurements were recorded for axial degradation at various locations in
the steam generators. Experience has shown that length measurements made
SOUTHERN CALIFORNIA EDISON Page 39
with the Plus Point probe tend to over-estimate the structurally significant portion
of a crack; hence a best-fit length distribution based on the Plus Point measured
lengths adds a degree of conservatism to the simulation. However, this degree
of conservatism is grossly unrealistic for freespan axial ODSCC/IGA, as verified
by pulled tube burst tests. Therefore, the Plus Point determined eggcrate crack
length distribution is applied in analyses of freespan degradation. Figure A2.2
shows a plot of the cumulative distribution function used as a crack length
sampling distribution. It is based on a log normal fit to the eggcrate Plus Point
data from EOC 8. Data for the mid cycle inspection also is plotted. Figure A2.2
shows that the modeling assumption of a constant distribution of EOC crack
lengths, independent of the cycle length, is justified.
Detection Capabilities of Eddy Current Probes
In Monte Carlo simulations, a probability of detection (POD) function is used to
model the detection capability of an eddy current probe. Because the
effectiveness of the eddy current probe dictates the percentage of cracks that
are able to grow deep enough to threaten the structural integrity of the steam
generator, it is important to employ a POD function that accurately reflects actual
inspection practices.
Freespan and eggcrate regions were inspected using a bobbin probe at both
Cycle 9 (EOC 8), Cycle 9 mid cycle outage and the Cycle 10 (EOC 9).
Destructive examinations were performed on three pulled tubes from SONGS
Unit 2 at EOC 8. Burst and leak rate tests were conducted along with extensive
metallographic sectioning. Crack depth versus length profiles were determined
on burst test crack faces. Maximum crack depths were evaluated at the
numerous locations of transverse metallographic sections. This information,
when combined with the results of analyses of field eddy current data allowed
the construction of curves of probability of detection versus crack depth.
SOUTHERN CALIFORNIA EDISON Page 40
It is recognized that eddy current signals from eggcrate supports can add to the
difficulty of detecting degradation in these locations. In this sense POD curves
for freespan ODSCC/IGA can be expected to be somewhat better than those for
ODSCC/IGA at support structures. Sensitivity studies have shown that, in the
context of the present ODSCC/IGA analysis with the observed numbers of
indications and growth rate distribution, there was no observable impact of
changes in POD curves of a magnitude likely to be associated with the presence
or absence of tube support structures. In contrast, when PWSCC is observed at
support structure locations, the interaction of tubes with these structures is a
defining consideration.
Historically, bobbin probe detection and sizing capability has been referenced to
maximum degradation depths. As noted in Appendix 1, the structurally
significant average depth is the parameter of interest for burst pressure
prediction. Figure A1.2 shows the relationship of structurally significant depth to
maximum axial crack depth. The typically ratio of maximum to structural depth is
1.28. This factor was used to convert maximum depth to structural depth in
construction of the probability of detection curves.
Degradation Growth Rates
During the simulation process, crack growth rates are sampled from a
distribution of crack growth rates. In the Cycle 9 SONGS Unit 2 analysis a single
crack growth rate distribution was used for axial degradation regardless of
location. It was the most aggressive crack growth rate distribution used in any
previous analysis. This adverse crack growth rate distribution is appropriate for
PWSCC at eggcrate locations. However, it is unduly conservative for
ODSCC/IGA at both freespan and eggcrate locations. The sole focus of Cycle 9
analysis was a conservative calculation of conditional probability of burst. This
goal was met but the choice of a very conservative crack growth rate distribution
contributed to an under prediction of the expected number of ODSCC/IGA
indications at both freespan and eggcrate locations at the mid cycle outage.
SOUTHERN CALIFORNIA EDISON Page 41
The distribution of Plus Point probe voltages of eggcrate and freespan
ODSCC/IGA indications at both EOC 8 and the mid cycle inspections was
compared to data from plants of similar design. Plus Point voltage is a
reasonable comparative gauge of degradation severity. The results for SONGS
Unit 2 over two operating periods point to crack growth rates which are toward
the lowest rather highest end of the spectrum of growth rates observed to date.
Consequently a moderate crack growth rate distribution was selected, one about
equal to that observed in another plant where two consecutive Plus Point upper
bundle inspections had been performed. A log normal distribution was used and
the standard deviation was increased slightly to a typical value of 0.65. This
increases the likelihood of encountering large growth rates and adds to the
conservatism of the analysis in a reasonable manner. Figure A2.3 illustrates the
crack growth rate distributions used for simulating PWSCC at eggcrate locations
and ODSCC/IGA at both freespan and eggcrate regions.
SOUTHERN CALIFORNIA EDISON Page 42
2000
1800iai
1600
1400
1200
IL
800.
600
400
2)00
110 115 120 125 130 135 14 145
Yield + Utiart• Sbu#h (kdi)
FIGURE A2.1
SOUTHERN CALIFORNIA EDISON Page 43
1.0
0.9
Mid Cycle Inspection Results, Eggcrate
0.8 - ODSCC / IGA
Log Normal Distribution
0.7 " f Used in Both Current and -" T Previous Analyses
0.6 ri
I ;
_ _ _ _I _ _ _ I _ _ _ _ 0.5
0.4
0.3 _ i : T *
- I __
0.2 _
0.1;
0 0 0.0 -" ____'
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80
Crack Length, inches
FIGURE A2.2
COMPARISON OF MID CYCLE EGGCRATE ODSCC/IGA
SOUTHERN CALIFORNIA EDISON Page 44
0
14U
E._ U0O
1.0
0.9
0.8
0.7
U. .>~ E0
E
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0 10 20 30
Crack Growth Rate, %TW / EFPY
Figure A2.3 Sampling Distributions For ODSCC I IGA and PWSCC Crack
Growth Rates
SOUTHERN CALIFORNIA EDISON Page 45
40
Appendix 3 - PROBABILISTIC MODEL
The probabilistic run-time model projects the processes that have contributed to
tube degradation over the history of a steam generator in order to assess the
structural condition of the generator at a future inspection. Specifically, Monte
Carlo simulation of the processes of crack initiation, crack growth, eddy current
inspection, and removal or repair of degraded tubes provides information
necessary to estimate the probability of tube burst and the magnitude of leakage
at the next scheduled inspection, given a postulated steam line break event.
The state of degradation of the steam generator tubing is simulated by a defect
population that is defined by several parameters. These are: the size of the
population at risk, the initiation function that describes crack inception, the
distributions of the defect geometries, and the growth rate distribution that
determines the change in crack depth over time.
The population at risk, in combination with the initiation function, determines the
total number of defects simulated in the analysis. The choice of population size
primarily influences the computational time and memory requirements of the
simulation. In cases where the choice of population at risk is not obvious from
physical considerations, care must be taken to avoid an unreasonably low value
that can prematurely exhaust the initiated defect population. For degradation
near expansion transitions the obvious population at risk is the number of tubes
in the bundle. For cracking at eggcrate intersections, some multiple of the
number of tubes in the bundle is appropriate. If the total population of degraded
sites is small compared to the total number of sites at risk, then the choice of the
number of sites at risk is not of concern other than perhaps creating unwarranted
memory requirements.
The initiation function for defects is based on a modified Weibull function, which
requires a scale parameter and a slope parameter. The scale parameter reflects
SOUTHERN CALIFORNIA EDISON Page 46
the length of time required to initiate a given percentage of all potential crack
sites. This parameter may be on the order of several decades. The slope
parameter is a measure of the rate of increase in initiated defects over time. The
scale and slope parameters are adjusted iteratively until the number of
indications produced by the simulation matches the actual number of flaws
detected at recent plant inspections. Having matched the number in indications
observed at recent inspections, other key benchmarking items include:
predicting the measured severity of degradation, confirming notable in situ test
results, and reproducing observed inspection transients.
A probabilistic analysis of degradation within a steam generator includes many
thousands of simulations that track the condition of the steam generator through
several past inspection periods to develop benchmark statistics. The model then
projects the degradation mechanism through the current operating cycle in order
to predict the structural condition of the generator as a function of cycle duration.
The present study considers all past inspections for which eddy current
inspection results are available.
Each mock operating cycle and inspection event within a single steam generator
simulation consists of several steps that trace the initiation and development of
individual cracks. For each potential crack site, a crack initiation time is- drawn at
random from a cumulative initiation function. A certain percentage of the crack
sites will have initiated during or prior to the operating cycle of interest.
For each initiated crack, a set of descriptive parameters is drawn at random from
appropriate distributions to describe the crack in detail. These parameters
include the crack length, the crack form factor, and the strength properties of the
tube in which the crack resides. The crack retains these particular features
throughout its entire life. A growth rate is then sampled from the growth rate
distribution. The growth rate is applied to the crack depth over the interval of
time between inspections. The growth is assumed to be linear in time. A new
SOUTHERN CALIFORNIA EDISON Page 47
growth rate is sampled after each simulated inspection and applied over the
ensuing operating cycle, which accounts for potential changes in local growth
environments due to start-up transients. The average depth of the crack
increases with time, and the maximum depth is correspondingly adjusted
according to the crack form factor.
Simulated inspections are performed according to the plant-specific inspection
schedules. The crack depth at the end of a completed operating cycle, together
with the POD curve, determine the probability that a particular crack will be
detected during an inspection. A random number is drawn from a uniform
distribution and compared to the POD. If the random draw is less than the POD,
the crack is detected and removed from service. Undetected cracks are left in
service and allowed to grow throughout the following operating cycle, and the
process is repeated at subsequent inspections.
All cracks, whether detected or undetected, are examined at the end-of-cycle
inspections to assess the probability of tube burst and leakage under steam line
break conditions. The algorithm records a burst if the accident pressure
differential exceeds the burst pressure for a particular flawed tube. If the
maximum crack depth exceeds the tube thickness, the flaw is considered to be
leaking. A potentially high leak rate can result from a "pop-through" event, which
occurs when the length of a particular defect is not sufficient to cause a full burst,
but the average depth of the crack is such that the crack breaks through-wall
over its entire structural length.
When all initiated cracks have been inspected over the course of prescribed past
and future operating cycles, a single Monte Carlo trial of the steam generator is
complete. Many thousands of such trials are necessary to generate the
distributions of tube burst and leakage rates required in the structural margin
assessments.
SOUTHERN CALIFORNIA EDISON Page 48
The output from the simulation algorithm consists of a record of all tubes that
have burst during the simulation, and all defects that have penetrated through
wall and are assumed to be leaking. Other pertinent data such as the operating
cycle during which the burst or leak event occurred, the tube material properties,
flaw length, and form factor are also recorded.
For a given operating cycle of interest, the number of burst events are tallied and
a 95% upper confidence bound for the probability of burst is computed using an
appropriate F-distribution, as in Reference 13. For example, if 10,000
simulations of the steam generator produce 1 or more bursts in 30 of the trials,
the 95% confidence probability of burst is calculated to be PoB = 0.00407.
A leak rate is assigned to each throughwall defect according to the methods
presented in Appendix 2. The total leak rate for each steam generator
simulation is then computed, the simulation leak rates are sorted in ascending
order, and the 95/95 probability/confidence leak rate is determined as described
in Reference 13. For example, for 10,000 steam generator simulations, the
9537' highest computed leak rate represents the 95th percentile leak rate with
95% confidence.
SOUTHERN CALIFORNIA EDISON Page 49
Summary of Structural Margin and Leak Rate Evaluations
A summary of calculated conditional probabilities of tube burst and upper bound
accident induced leak rates is provided in Table 6 for the six corrosion
degradation mechanisms considered in this evaluation. The limiting mode of
degradation is PWSCC at eggcrate intersections relative to conditional
probability of tube burst. In terms of projected leak rates at postulated accident
conditions, circumferential degradation a the top of the tubesheet is the dominant
consideration. Calculated conditional probabilities of tube burst and projected
upper bound SLB leak rates at EOC 10 meet the requirements of NEI 97-06.
SOUTHERN CALIFORNIA EDISON Page 50
Appendix 4
ODSCCIIGA at Eggcrate Intersections
ODSCC/IGA degradation at eggcrate locations were efficiently removed from
service during the mid cycle outage. This was the expectation since the mid
cycle outage inspection was critically focused on eggcrate and freespan
locations. The predicted probability of burst at MSLB for this mechanism
following 1.67 EFPY of operation in cycle 10 is <0.0001 and the corresponding
leak rate at MSLB is 0.00.
Inputs:
Inspection POD Growth Initiation Sizing Error
I• ::> 2 >
Data from (. 0 N '6 -2 0 0 Outages a0 T• 0 W 03 LL 030
8, 9, 9M, & 10
0 C14 M • C')I
• - -T ,--- - - -- - - - .
VERSION AxMultilb.exe 5/5/98
Indications Observed SG 88/89
Mechanism 2C8 2C9 2M9 2C10 ODSCC @ EGGCRATES 0-1 8-9 25-32 10-12
Simulation PredictionsMean Standard Deviation
SOUTHERN CALIFORNIA EDISON
Mechanism 2C8 2C9 I 2M9 t 2C10 2C8 2C9 2M9 2C10 ODSCC @ EGGCRATES 13 13 22 14 4 4 5 4
D:\OPCON_050798\AxMulti\AXSUB\odtsp1 b.out
# Sims # Tubes Sites/Tube
SLB NOP Leak Limit
20000 9350 1
2.575 1.46 0.01
Tube Wall Mean Strength Max Strength Young's Modulus
Mean Ln(Growth Rate) Max Growth Rate
Initiation Slope 2 Initiation Scale 100 Initiation Setback 0
Mean Error 0 Error Std Dev 0.0375 Max Error I
Tube OD 0.75 Strength Std Dev 5.73 Min Strength 123
Std Dev of Mean 0.4 Fraction Zero Growth 0
0.048 132.51 143 28700000
1.6 100
Cycle, EFPY 8.62 10.09 10.85 11.66 13.33
Fraction Inspct. 1.0 1.0 1.0 1.0 1.0
Repair Limit -99.0 -99.0 -99.0 -99.0 -99.0
POD Fit UL UL UL L/L L/L
POD Intercept 12.742 12.742 19.72 19.72 19.72
POD Slope -8.139 -8.139 -14.089 -14.089 -14.089
Input File Name
OUTPUT FILE:"D:\OPCON 050798fAxMulti•AX SUBlodtspl b.out"
Cycle, EFPY 8.62 10.09 10.85 11.66 13.33 POL at SLB 0.1703 0.014 0.0006 0 0.0001 POL >Limit at SLB 0.0558 0.0022 0.0001 0 0 POL >Limit at NOP 0.0374 0.001 0.0001 0 0 95195 Leak at SLB, NOP 0.016 0 0 0 0
# Sims w/Bursts 3 0 0 0 0 POB at SLB (95%) 0.0004 0.0001 0.0001 0.0001 0.0001 POB at 3DP 0.0118 0.001 0.0001 0 0
Initiated 69.58 25.58 14.74 16.8 38.86 In Service 69.58 82.51 83.77 78.91 104.04 Mean # Detected 12.64 13.49 21.65 13.74 25.7 Std Dev, # Detected 3.59 3.52 4.56 3.57 5.05 Mean # Known In Service 12.64 13.49 21.65 13.74 25.7 Std Dev, # Known In Servic 3.59 3.52 4.56 3.57 5.05 Cumulative # Detected, Me 12.64 26.13 47.79 61.52 87.22 Cumulative # Detected, Stc 3.59 4.99 6.65 7.49 9.19 Mean # Plugged 12.64 13.49 21.65 13.74 25.7 Std Dev, # Plugged 3.59 3.52 4.56 3.57 5.05 Cumulative # Plugged, Mes 12.64 26.13 47.79 61.52 87.22 Cumulative # Plugged, Std 3.59 4.99 6.65 7.49 9.19 Mean Maximum Depth 0.643 0.487 0.418 0.311 0.368 Std Dev, Maximum Depth 0.165 0.094 0.063 0.039 0.043
TRUE Depth, % Through Wall
I-
TRUE DEPTH 8.62 10.09 10.85 11.66 13.33
5 10 15 20 25 30 35 40 45 50 55 60 65
70 75 80 85 9o 95
100
I 16.29 13.59 11.05 8.51 6.33 4.45 3.03 2.05 1.36 0.9
0.58 0.38 0.25
0.16 0.11 0.07 0.05 0.03 0.02 0.05
18.62 14.76 14.04 11.99 9.05 6.1
3.68 1.98 1.01 0.49 0.23 0.11 0.06
0.03 0.01 0.01
0 0 0 0
DETECTED Depth, % Through Wall
5 10 15
20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
DETECTED DEPTH 8.62 10.09 10.85 11.0.01 0.13 0.57 1.24 1.86 2.02 1.83 1.46 1.08 0.76 0.52 0.35 0.23
0.15 0.1
0.07 0.05 0.03 0.02 0.05
0.01 0.15 0.74 1.78 2.67 2.78 2.21 1.41 0.8
0.42 0.21
0.1 0.05
0.02 0.01 0.01
0 0 0 0
0 0.07
1 4.2
6.45 5.07 2.83 1.28 0.5
0.18 0.07 0.02 0.01
0 0 0 0 0 0 0
0 0.08 1.09 4.25 5.14 2.41 0.66 0.14 0.03 0.01
0 0 0 0 0 0 0 0 0 0
13.330 0.08 1.25 5.62 8.83 6.33 2.54 0.71 0.17 0.04 0.01
0 0 0 0 0 0 0 0 0
19.08 16.89 14.48 12.76 9.47 5.78 2.97
1.3 0.5
0.18 0.07 0.02 0.01
0 0 0 0 0 0 0
20.56 17.67 16.28 12.91 7.67 2.76 0.69 0.14 0.03 0.01
0 0 0
0 0 0 0 0 0 0
25.11 19.7
17.89 16.81 13.01 7.23 2.67 0.72 0.17 0.04 0.01
0 0 0 0 0 0 0 0 0
66 13.33l
MEASURED Depth, % Throunh Wall
MEASURED DEPTH 8.62 10.09 10.85 11.66 13.33
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
0.05 0.22 0.63 1.22 1.74 1.93 1.78 1.44 1.11 0.78 0.54 0.37 0.24 0.16 0.11 0.07 0.05 0.05 0.01 0.04
TRUE Depth, % Throuah Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
I-.
TRUE DEPTH 8.62 10.09 10.85 11.66 13.33
0.2352 0.43142 0.59096 0.71383 0.80523 0.86948 0.91323 0.94282 0.96246 0.97545 0.98383 0.98932 0.99293 0.99524 0.99682 0.99783 0.99856 0.99899 0.99928
1
0.2266 0.40623 0.5771
0.72301 0.83315 0.90739 0.95217 0.97627 0.98856 0.99452 0.99732 0.99866 0.99939 0.99976 0.99988
1 1 1 1 1
0.22848 0.43073 0.60412 0.75692 0.87031 0.93953 0.97509 0.99066 0.99665 0.9988
0.99964 0.99988
1 1 1 1 1 1 1 1
0.26118 0.48565 0.69245 0.85645 0.95389 0.98895 0.99771 0.99949 0.99987
1 1 1 1 1 1 1 1 1 1 1
0.24294 0.43353 0.60662 0.76925 0.89512 0.96507 0.99091 0.99787 0.99952
0.9999 1 1 1 1 1 1 1 1 1 1
0.05 0.27 0.86 1.75 245 2.58 2.15 1.46 0.87 0.47 0.23 0.12 0.06 0.03 0.01 0.01
0 0 0 0
0.03 0.32 1.56 3.95 5.52 4.82 2.99 1.49 0.62 0.24 0.09 0.03 0.01
0 0 0 0 0 0 0
0.04 0.35
1.6 3.68 4.21 2.62 0.98 0.26 0.06 0.01
0 0 0
0 0 0 0 0 0 0
0.04 0.41 2.04
5.3 7.36 5.98 3.01 1.06 0.29 0.07 0.02
0 0 0 0 0 0 0 0 0
Y
DETECTED Depth, % Through Wall
T .1-
DETECTED DEPTH 8.62 10.09 10.85 11.66 13.33
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
0.0008 0.01117 0.05666 0.15563 0.30407 0.46528 0.61133 0.72785 0.81405
0.8747 0,9162
0.94413 0.96249
0.97446 0.98244 0.98803 0.99202 0.99441 0.99601
1
0.00075 0.01197 0.06731 0.20045 0.40015 0.60808 0.77337 0.87883 0.93867 0.97008 0.98579 0.99327 0.99701
0.9985 0.99925
1 1 1 1 1
MEASURED Depth, % Throuah Wall
5 10 15 20 25 30 35 40 45 50 55 60 65
70 75 80 85 90 95
100
MEASURED DEPTH 8.62 10.09 10.85 11.66
0.00399 0.02153 0.07177 0.16906 0.30781 0.46172 0.60367 0.7185
0.80702 0.86922 0.91228 0.94179 0.96093
0.97368 0.98246 0.98804 0.99203 0.99601 0.99681
1
0.00374 0.02393 0.08826 0.21915 0.40239 0.59536 0.75617 0.86537 0.93044 0.96559
0.9828 0.99177 0.99626
0.9985 0.99925
1 1 1 1 I
0.00138 0.0029 0.01615 0.02824 0.08814 0.1441 0.27042 0.41057 0.52515 0.71542 0.74758 0.90514 0.88556 0.9761 0.95431 0.99493 0.98293 0.99928
0.994 1 0.99815 1 0.99954 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0.00156 0.01759 0.09734 0.30453 0.59226 0.82604 0.94371 0.98514 0.99648 0.99922
1 1 1 1 1 1 1 1 1 1
0 0.00323 0.04935 0.24308 0.54059 0.77445 0.90498 0.96402 0.98708 0.99539 0.99862 0.99954
1
1 1 1 I 1 1 1
0 0.00579 0.08472 0.39247 0.76466 0.93917 0.98697 0.9971
0.99928 1 1 1 1
1 1 1 1 1 1 1
0 0.00313 0.05199
0.2717 0.61689 0.86435 0.96364
0.9914 0.99805 0.99961
1 1 1
1 1 1 1 1 1 1
13.3313.33% Throuah Wall
Leak Rate, gpmI
LEAK RATE 8.62EFPY 10.09EFPN 10.85EFPN 11.66EFPN 13.33EFPY
1.80E-07 3.20E-07 5.60E-07 1.00E-06 1.80E-06 3.20E-06 5.60E-06 I.0OE-05 1.80E-05 3.20E-05 5.60E-05 I.OOE-04 1.80E-04
3.20E-04 5.60E-04 1.OOE-03 1.80E-03 3.20E-03 5.60E-03 I.OOE-02 1.80E-02 3.20E-02 5.60E-02 1.OOE-01 1.80E-01 3.20E-01 5.60E-01 I.OOE+O0 1.80E+00 3.20E+00 5.60E+00 I.OOE+01 1.80E+01 3.20E+01 5.60E+01 1.OOE+02 1.80E+02 3.20E+02 5.60E+02 I.OOE+03
0.8328 0.8339 0.8345 0.8357
0.837 0.8389 0.8413 0.8446 0.8483 0.8533 0.8598 0.866
0.8733
0.8829 0.8925 0.9029 0.9131 0.9238 0.9333 0.9442 0.9543 0.9631 0.9719 0.9809 0.9876 0.9908 0.9935 0.9958 0.9971
0.998 0.9989 0.9994 0.9998 0.9999
1 1 1 1 1 1
0.9865 0.9867 0.9869 0.9871 0.9873 0.9875 0.9879 0.9885 0.9887 0.9891
0.99 0.9909 0.9918
0.9927 0.9937 0.9946 0.9959
0.997 0.9974 0.9979 0.9984 0.9988 0.9992 0.9995 0.9997 0.9998 0.9998 0.9998 0.9999 0.9999 0.9999
1 1 1 1 1 1 1 1 1
0.9994 0.9994 0.9994 0.9994 0.9994 0.9994 0.9994 0.9995 0.9995 0.9995 0.9996 0.9996 0.9996
0.9997 0.9998 0.9998 0.9998 0.9998 0.9999 0.9999 0.9999 0.9999 0.9999
1 1 1 1 1 1 1 1 I 1 1 I 1 1 1 1 1
Burst Pressure psi 250 500
750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000 5250 5500 5750 6000 6250 6500 6750 7000 7250 7500 7750 8000 8250
.8500 8750 9000 9250 9500 9750
10000 10250 10500 10750 11000 11250 11500 11750 12000 12250 12500 12750 13000 13250
BURST PRESSURE 8.62EFPY 10.09EFPN 10.85EFPN 11.66EFPN 13.33EFPY
0 0.0001 0.0001 0.0001 0.0001 0.0001 0.0002 0.0002 0.0002 0.0003 0.0004 0.0005 0.0006
0.0007 0.0009 0.0012 0.0015 0.0019 0.0023 0.003
0.0038 0.0048 0.0061 0.0079 0.0101 0.013
0.0168 0.0217 0.0282 0.0365 0.0473 0.061
0.0787 0.1017 0.1306 0.1676 0.2136 0.2702 0.3389 0.4207 0.5166 0.6238 0.7294 0.8266 0.9038 0.9551 0.9839 0.9972
1 1 1 I 1
0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0
0.0001 0.0001 0.0001 0.0002 0.0003 0.0004 0.0007 0.001
0.0015 0.0023 0.0035 0.0054 0.0083 0.0127 0.0195
0.03 0.0449 0.0669 0.0976 0.1383 0.1913 0.2575 0.3365
0.427 0.5286 0.6375 0.7413 0.8344 0.9077 0.9572 0.9845 0.9972
1 1 1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0.0001 0.0001 0.0002 0.0004 0.0007 0.0014 0.0025 0.0046 0.0082 0.0147 0.0255 0.0426 0.0686 0.1065 0.1583 0.2248 0.3057 0.4003 0.5061 0.6203 0.7298 0.8277 0.9048 0.9561 0.9841 0.9971
1 1 1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0002 0.0006 0.0015 0.0039 0.0094 0.0212 0.044
0.0827 0.1413 0.2211 0.3217 0.4392 0.5692 0.6934 0.8048 0.8919 0.9495 0.9817 0.9966
1 1 1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0002 0.0004
0.001 0.0025 0.0056 0.0124 0.0255 0.0489
0.086 0.1391 0.2096 0.2949 0.3923 0.5006 0.6156 0.7249 0.8234 0.9013 0.954
0.9836 0.9971
1 1 1 1 1
Appendix 5
Axial PWSCC at "Dented" Eggcrate Intersections
As noted previously, PWSCC, on mechanistic grounds, is associated with
deformed or dented eggcrate intersections, even if there is no detectable denting
via eddy current inspection. The largest observed axial cracks at EOC 8 were ID
initiated. Axial PWSCC at eggcrate intersections was the limiting form of
degradation at SONGS Unit 2. Recent inspection results indicate that the trend is
improving. The calculated conditional probability of burst at MSLB at EOC 10 is
0.001 and the associated 95/95 leak rate at postulated SLB conditions is 0.011
GPM.
Inputs:
Inspection POD Growth Initiation Sizing Error
Data'from r, C-L- N CL (•n• • ax 0 0&coc
ts20 0 Outages e onC CO Z
9, 9M, & 10
NO4 0 0C4 ,- -. -T ,- - --- -:< o o o ,
VERSION AxMultilb.exe 5/5/98
Indications Observed
SG 88189 Mechanism 2C9 2M9 2C10
PWSCC @ EGGCRATES 3-4 6-9 3-6
Simulation Predictions Mean Standard Deviation
Mechanism 2C9 2M9 2C10 2C09 I2M9 I 2C10 PWSCC @ EGGCRATES 3 6 6 2 3 3
SOUTHERN CALIFORNIA EDISON
D:\OPCON_050798\AxMulti\idegg.out
# Sims # Tubes Sites/Tube
SLB NOP Leak Limit
20000 9350 1
2.575 1.46 0.01
Tube Wall Mean Strength Max Strength Young's Modulus
Mean Ln(Growth Rate) Max Growth Rate
Initiation Slope 4.9 Initiation Scale 34 Initiation Setback 0
Mean Error 0 Error Std Dev 0.2 Max Error I
Tube OD 0.75 Strength Std Dev 5.73 Min Strength 123
Std Dev of Mean 0.65 Fraction Zero Growth 0
0.048 132.51 143 28700000
1.95 100
Cycle, EFPY 10.09 10.85 11.66 13.33
Fraction Inspct. 1.0 1.0 1.0 1.0
Repair Limit -99.0 -99.0 -99.0 -99.0
POD Fit L/L L/L L/L L/L
POD Intercept 12.742 20.65 20.65 20.65
POD Slope -7.5 -14.39 -14.39 -14.39
Input File Name
OUTPUT FILE:"D:\OPCON 050798\AxMulti\idefqc.out"
Cycle, EFPY 10.09 10.85 11.66 13.33 POL at SLB 0.3085 0.0371 0.0023 0.1266 POL >Limit at SLB 0.181 0.0109 0.0003 0.0483 POL >Limit at NOP 0.1617 0.0077 0.0003 0.0367 95195 Leak at SLB, NOP 0.331 0 0 0.011
# Sims wlBursts 38 3 0 13 POB at SLB (95%) 0.0025 0.0004 0.0001 0.001 POB at 3DP 0.0355 0.0045 0.0004 0.0191
Initiated 24.3 10.27 14.56 45.24 In Service 24.3 31.99 40.11 79.03 Mean # Detected 2.58 6.44 6.32 18.29 Std Dev, # Detected 1.64 2.64 2.5 4.37 Mean # Known In Service 2.58 6.44 6.32 18.29 Std Dev, # Known In Servic 1.64 2.64 2.5 4.37 Cumulative # Detected, Me 2.58 9.03 15.35 33.64 Cumulative # Detected, Stc 1.64 3.14 3.99 5.98 Mean # Plugged 2.58 6.44 6.32 18.29 Std Dev, # Plugged 1.64 2.64 2.5 4.37 Cumulative # Plugged, Mei 2.58 9.03 15.35 33.64 Cumulative # Plugged, Std 1.64 3.14 3.99 5.98 Mean Maximum Depth 0.691 0.455 0.358 0.606 Std Dev, Maximum Depth 0.378 0.139 0.085 0.18
TRUE Depth, % Through Wall
DETECTED Depth, % Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
TRUE DEPTH 10.09 10.85 11.66I5
10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
DETECTED DEPTH 10.09 10.85 11.66 13.33
0 0 0 0 0.03 0.02 0.02 0.03 0.08 0.2 0.27 0.42 0.15 0.82 1.21 1.99 0.21 1.38 1.98 3.99 0.26 1.29 1.47 4.14 0.27 0.96 0.74 3.04 0.25 0.62 0.33 1.92 0.23 0.39 0.13 1.14 0.2 0.24 0.06 0.69
0.17 0.15 0.03 0.42 0.14 0.09 0.01 0.26 0.12 0.06 0.01 0.17 0.09 0.03 0 0.11 0.08 0.02 0 0.07 0.06 0.01 0 0.05 0.05 0.01 0 0.03 0.04 0.01 0 0.02 0.03 0 0 0.01 0.19 0.01 0 0.04
8.13 5.04 3.25 2.15 1.48 1.05 0.76 0.54 0.41 0.31 0.23 0.18 0.14 0.11 0.09 0.07 0.05 0.05 0.04
0.2
13.339.84 6.6
5.14 3.63 2.44 1.58 1.03 0.64 0.39 0.24 0.15 0.09 0.06 0.03 0.02 0.01 0.01 0.01
0 0.01
13.24 8.26 6.76 5.29 3.5 1.8 0.8
0.34 0.14 0.06 0.03 0.01 0.01
0 0 0 0 0 0 0
24.61 15.15 10.77 8.62 6.94 5.04 3.27 1.98 1.15 0.69 0.42 0.26 0.17 0.11 0.07 0.05 0.03 0.02 0.01 0.04
I
MEASURED Depth,% Through Wall
1€
23
241 25
30 35 40 45 80 85 60 65 70 75 80 85 90 95
300i
TRUE Depth, % Througlh Wall
5 10 45 20 25 30 35 40 45 80 55 s0 65 70 75 80 85 90 95ý
100
MEASURED DEPTH10.09 10.85 11.66 13.33
5 0.2 0.86 1.08 2.4 0 0.09 0.36 0.43 1 5 0.11 0.43 0.5 1.23 0 0.13 0.5 0.55 1.45
0.15 0.53 0.59 1.57 0.16 0.54 0.59 1.64 0.17 0.54 0.55 1.6 0.17 0.52 0.49 1.53 0.18 0.46 0.41 1.38 0.17 0.41 0.33 1.18 0.16 0.32 0.25 0.96 0.15 0.25 0.18 0.76 0.14 0.19 0.12 0.58 0.13 0.14 0.09 0.42 0.11 0.1 0.05 0.31 0.11 0.07 0.03 0.22 0.11 0.05 0.02 0.15 0.09 0.03 0.01 0.1 0.02 0.02 0.01 0.04 0.08 0 0 0.01
TRUE DEPTH 10.09 10.85 11.66 13.33
0.33484 0.30827 0.32903 0.30995 0.54242 0.51504 0.53429 0.50076 0.67628 0.67607 0.70229 0.6364 0.76483 0.78979 0.83375 0.74496 0.82578 0.86623 0.92073 0.83237 0.86903 0.91573 0.96546 0.89584 0.90033 0.94799 0.98534 0.93703 0.92257 0.96805 0.99379 0,96196 0.93946 0.98026 0.99727 0.97645 0.95222 0.98778 0.99876 0.98514 0.9617 0.99248 0.9995 0.99043
0.96911 0.9953 0.99975 0.9937 0.97488 0.99718 1 0.99584 0.97941 0.99812 1 0.99723 0.98311 0.99875 1 0.99811
0.986 0.99906 1 0.99874 0.98806 0.99937 1 0.99912 0.99012 0.99969 1 0.99937 0.99176 0.99969 1 0.9995
1 1 1 1
DETECTED Depth, % Through Wall
I-
DETECTED DEPTH 10.09 10.85 11.66 13.33
5 10 15 20 25 30 35 40 45 50 55 60 65
70 75 80 85 90 95
100
MEASURED Depth, % Throuah Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
I-
MEASURED DEPTH 10.09 10.85 11.66 13.33
0.07605 0.11027 0.15209 0.20152 0.25856 0.31939 0.38403 0.44867 0.51711 0.58175 0.64259 0.69962 0.75285
0.80228 0.84411 0.88593 0.92776 0.96198 0.96958
1
0. 13608 0.19304 0.26108 0.34019 0.42405 0.50949 0.59494 0.67722
0.75 0.81487 0.86551 0.90506 0.93513
0.95728 0.9731
0.98418 0.99209 0.99684
1 1
0.17197 0.24045 0.32006 0.40764 0.50159 0.59554 0.68312 0.76115 0.82643 0.87898 0.91879 0.94745 0.96656
0.98089 0.98885 0.99363 0.99682 0.99841
1 1
0.12952 0.18349 0.24987 0.32812 0.41284 0.50135
0.5877 0.67026 0.74474 0.80842 0.86023 0.90124 0.93254 0.95521 0.97194 0.98381 0.99191
0.9973 0.99946
1
I
0 0.01132 0.04151 0.09811 0.17736 0.27547 0.37736 0.4717
0.55849 0.63396 0.69811 0.75094 0.79623
0.83019 0.86038 0.88302 0.90189 0.91698
0.9283 1
0 0.00317 0.03487 0.16482 0.38352 0.58796
0.7401 0.83835 0.90016 0.93819 0.96197 0.97623 0.98574 0.99049 0.99366 0.99525 0.99683 0.99842 0.99842
1
0 0.00319 0.04633 0.23962 0.55591 0.79073 0.90895 0.96166 0.98243 0.99201 0.99681
0.9984 1
1 1 1 1 I 1 1
0 0.00162 0.02427 0.13161 0.34682 0.57012 0.73409 0.83765 0.89914 0.93635 0.95901 0.97303
0.9822 0.98813 0.99191 0.99461 0.99622 0.9973
0.99784 1
% Throuah Wall
LEAK RATE 10.09EFPN 10.85EFPN 11.66EFP'N 13.33EFPYLeak Rate , pm
1.80E-07 3.20E-07 5.60E-07 1.00E-06 1.80E-06 3.20E-06 5.60E-06 I1OOE-05 I.80E-05 3.20E-05 5.60E-05 1.00E-04 1.80E-04
3.20E-04 5.60E-04 I.OOE-03 1.80E-03 3.20E-03 5.60E-03 1.00E-02 1.80E-02 3.20E-02 5.60E-02 1.OOE-O1 1.80E-01 3.20E-01 5.60E-01 1.OOE+0O 1.80E+00 3.20E+00 5.60E+00 1.OOE+o1 1.80E+01 3.20E+01 5.60E+01 I.OOE+02 1.80E+02 3.20E+02 5.60E+02 1.OOE+03
0.6939 0.6945 0.6955 0.6962 0.6972 0.6989 0.7009 0.7037 0.7065 0.7104 0.7155 0.7213 0.7288
0.7365 0.7466 0.7573 0.7703 0.7847
0.801 0.8189 0.8391 0.8631 0.8883 0.915
0.9362 0.9514 0.9623
0.972 0.9806 0.9867 0.9906 0.9937 0.9958 0.9972 0.9982 0.9987 0.9992 0.9993 0.9996
1
0.9636 0.9638
0.964 0.9645 0.9649 0.9653 0.9658 0.9665
0.967 0.968
0.9692 0.9708 0.9728
0.9752 0.9778 0.9802 0.9828 0.9849 0.9874 0.9891 0.9911 0.9926
0.994 0.9954 0.997
0.9976 0.9981 0.9986 0.9988 0.9991 0.9994 0.9997 0.9999
1 1 1 1 1 1 1
0.9978 0.9978 0.9978 0.9978 0.9978 0.9979 0.9979 0.9979 0.998 0.998
0.9981 0.9983 0.9986
0.9988 0.999
0.9992 0.9994 0.9995 0.9996 0.9997 0.9998 0.9998 0.9998 0.9998 0.9999
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0.8758 0.8764 0.8773 0.8782 0.8792 0.8807 0.8823 0.8841 0.8876 0.8903 0.8946 0.8991 0.9048
0.9109 0.9181 0.9241 0.9315 0.9391 0.9452 0.9517 0.9585 0.9657 0.9728
0.98 0.9853 0.9884 0.9907 0.9925 0.9942 0.9963 0.9975 0.9982 0.999
0.9992 0.9996 0.9997 0.9998 0.9999
1 1
Burst Pressure, psiBURST PRESSURE
10.09EFPN 10.85EFPN 11.66EFPN 13.33EFPY250 500 750
1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000 5250 5500 5750 6000 6250 6500 6750 7000 7250 7500 7750 8000 8250 8500 8750 9000 9250 9500 9750
10000 10250 10500 10750 11000 11250 11500 11750 12000 12250 12500
0.0025 0.0027 0.0029 0.0032 0.0035 0.0038 0.0042 0.0046 0.0051 0.0055 0.0061 0.0067 0.0074
0.0081 0.009 0.01
0.0111 0.0124 0.014
0.0157 0.0176 0.0199 0.0225 0.0253 0.0288 0.0327 0.0375 0.0433 0.0498 0.0574 0.0667 0.0782 0.0919 0.1086
0.129 0.1539 0.1852 0.225
0.2754 0.3409 0.4272 0.5365
0.652 0.7669 0.8652 0.9353 0.9756 0.9953
1 1
I
0 0 0
0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0002 0.0002 0.0003 0.0003 0.0004 0.0005 0.0006 0.0008 0.0011 0.0014 0.0017 0.0023
0.003 0.0039 0.0049 0.0065 0.0086 0.0114 0.0152 0.0202 0.027
0.0361 0.0483 0.0645 0.0859 0.1144 0.1511 0.1997 0.2621 0.3398 0.4349 0.5502 0.6673 0.7798 0.8739 0.9395 0.9771 0.9954
1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0001 0.0001 0.0002 0.0003 0.0004 0.0006 0.0009 0.0013 0.0021 0.0034 0.0056 0.0093 0.0156 0.0257 0.0423 0.0681 0.1057 0.1572 0.2244 0.3077 0.4096 0.5301 0.6514 0.7682 0.866
0.9353 0.9752
0.995 1 1
0.0001 0.0001 0.0001 0.0001 0.0001 0.0002 0.0002 0.0002 0.0002 0.0003 0.0004 0.0004 0.0005 0.0006 0.0007 0.0009 0.001
0.0013 0.0016
0.002 0.0025 0.0031 0.0039 0.005
0.0063 0.0081 0.0106 0.0138 0.0181 0.024
0.0321 0.0432 0.0585 0.079
0.1056 0.14
0.1828 0.2348 0.2963 0.3697 0.4588 0.5659 0.6768 0.7852 0.8762 0.9404 0.9777 0.9957
1 1
Appendix 6
Axial ODSCCIIGA at Freespan Locations
Axial ODSCC/IGA was detected at SONGS Unit 2 at freespan locations at the EOC 8 inspection. This is not unexpected in view of the performance of similar steam generators. This degradation was discovered by the bobbin probe after chemical cleaning of the unit. Plus Point inspections were performed in tubes with bobbin probe indications. The low signal amplitudes of Plus Point indications argued for mild severity of freespan axial degradation. This was confirmed by burst tests of pulled tubes. The burst strength of pulled tube sections with axial freespan indications was in excess of 10,000 psi. The magnitude of Plus Point voltages of freespan indications at the mid cycle inspection is smaller than those of the EOC 8 inspection. The numbers of freespan indication was reduced primarily by the efficiency of the mid cycle outage at removing tubes with indications of this mode from service. The calculated 95/95 SLB leak rate is zero.
Inputs:
Inspection POD Growth Initiation Sizing Error - - , -> 2 -V
Data from 4) a) 0 " Outages .o 4) o . o o
C (0 coc
9M & 10
0..0 0 ( c( •0 04
V-RI - O •-u T- -5/5/98 VERSION AxMultilb.exe 5/5/98
Mechanism 2CI FREESPAN ODSCC
SOUTHERN CALIFORNIA EDISON
D:\OPCON_050798\AxMulti\odfs36.out
# Sims # Tubes Sites/Tube
SLB NOP Leak Limit
20000 9350 1
2.575 1.46 0.01
Tube Wall Mean Strength Max Strength Young's Modulus
Mean Ln(Growth Rate) Max Growth Rate
Initiation Slope 1.5 Initiation Scale 160 Initiation Setback 0
Mean Error 0 Error Std Dev 0.2 Max Error 1
Tube OD 0.75 Strength Std Dev 5.73 Min Strength 123
Std Dev of Mean 0.1 Fraction Zero Growth 0
0.048 132.51 143 28700000
1.95 100
Cycle, EFPY 10.85 11.7 13.33
Fraction Inspct. 1.0 1.0 1.0
Repair Limit -99.0 -99.0 -99.0
POD Fit L/L L/L L/L
POD Intercept 19.72 19.72 19.72
POD Slope -14.09 -14.09 -14.09
Input File Name
OUTPUT FILE:"D:\OPCON 050798XAxMulti\odfs36.out"
Cycle, EFPY 10.85 11.7 13.33 POL at SLB 0.8984 0.0022 0 POL >Limit at SLB 0.1321 0.0001 0 POL >Limit at NOP 0.0519 0.0001 0 95195 Leak at SLB, NOP 0.041 0 0
# Sims wlBursts 44 0 0 POB at SLB (95%) 0.0028 0.0001 0.0001 POB at 3DP 0.3468 0.0006 0
Initiated 163.26 19.66 38.83 In Service 163.26 80.19 98.74 Mean # Detected 102.73 20.28 32.89 Std Dev, # Detected 10.13 4.51 5.85 Mean # Known In Service 102.73 20.28 32.89 Std Dev, # Known In Servic 10.13 4.51 5.85 Cumulative # Detected, Me 102.73 123 155.89 Cumulative # Detected, Stc 10.13 11.3 12.78 Mean # Plugged 102.73 20.28 32.89 Std Dev, # Plugged 10.13 4.51 5.85 Cumulative # Plugged, Mei 102.73 123 155.89 Cumulative # Plugged, Std 10.13 11.3 12.78 Mean Maximum Depth 0.819 0.392 0.376 Std Dev, Maximum Depth 0.055 0.076 0.036
TRUE Depth, % Through Wall
DETECTED Depth, % Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
10.854
0 0.07 1.01 4.75 9.35
11.38 11.61 11.26 10.61 9.77 8.84 7.73 6.39 4.74 3.01 1.57 0.65 0.22 0.07 0.02
DETECTED DEPTH 11.7 13.33
0 0.07 1.06 4.71 7.09 4.45 1.78 0.66 0.26 0.11 0.05 0.03 0.01
0.01 0 0 0 0 0 0
0 0.08 1.14 5.32
10.23 9.85 4.77 1.16 0.19 0.03
0 0 0 0 0 0 0 0 0 0
10.85TRUE 11.7
DEPTH 13.33
11.7 13.335
10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
15.77 15.26 14.68 14.15 13.54 12.88 12.16 11.48
10.7 9.82 8.86 7.74 6.39 4.74 3.01 1.58 0.65 0.22 0.07 0.02
16.39 15.71 15.29 14.17 10.45 5.09 1.87 0.67 0.26 0.11 0.05 0.03 0.01 0.01
0 0 0 0 0 0
17.45 16.91 16.16 15.83 14.88 11.21 5.02 1.19 0.19 0.03
0 0 0 0 0 0 0 0 0 0
MEASURED Depth, % Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
95 100
10.854
7.06 3.3
4.27 5.25 6.18
7 7.57 7.94 8.06 7.82 7.41 6.77 5.96 5.13 4.25 3.45 2.66 1.98 0.95 0.01
MEASURED DEPTH 11.7 13.333.79 1.44 1.68 1.85 1.92 1.89 1.74 1.53 1.29 1.01 0.75 0.54 0.36 0.23 0.14 0.08 0.04 0.02 0.01
0
5.53 2.21 2.66 2.96 3.11 3.1
2.94 2.61
2.2 1.74 1.31 0.92
0.6 0.4
0.24 0.13 0.07 0.04 0.02
0
TRUE Depth, % Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
10.850.09632 0.18953 0.2792
0.36562 0.44833
0.527 0.60127 0.67139 0.73675 0.79673 0.85084 0.89812 0.93715
0.9661 0.98449 0.99414 0.99811 0.99945 0.99988
1
TRUE DEPTH 11.7 13.33
0.20459 0.4007
0.59156 0.76844 0.89889 0.96243 0.98577 0.99413 0.99738 0.99875 0.99938 0.99975 0.99988
1 1 1 1 1 1 1
0.17649 0.34753 0.51097 0.67108 0.82158 0.93497 0.98574 0.99777
0.9997 1 1 1 1
1 1 1 1 1 1 1
DETECTED Depth, % Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65
70 75 80 85 90 95
100
10.8S
0 0.00068 0.01048 0.05657 0.14731 0.25774
0.3704 0.47967 0.58263 0.67744 0.76322 0.83823 0.90024 0.94624 0.97545 0.99068 0.99699 0.99913 0.99981
1
DETECTED DEPTH 11.7 13.33
0 0.00345 0.05569 0.28783 0.63726 0.85658 0.94431 0.97684 0.98965 0.99507 0.99754 0.99901 0.99951
1 1 1 1 1 1 1
0 0.00244 0.03723 0.19957 0.51175 0.81233 0.95789 0.99329 0.99908
1 1 1 1
1 1 1 1 1 1 1
MEASURED Depth, % Throuah Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
MEASURED DEPTH 10.85 11.7 13.33
0.06853 0.10056 0.14201 0.19297 0.25296 0.32091 0.39439 0.47146 0.5497
0.62561 0.69753 0.76325 0.8211
0.8709 0.91215 0.94564 0.97146 0.99068
0.9999 1
0.18661 0.16865 0.25751 0.23605 0.34023 0.31717 0.43131 0.40744 0.52585 0.50229 0.61891 0.59683 0.70458 0.68649 0.77991 0.76609 0.84343 0.83318 0.89316 0.88625 0.93008 0.9262 0.95667 0.95425
0.9744 0.97255
0.98572 0.98475 0.99261 0.99207 0.99655 0.99604 0.99852 0.99817 0.99951 0.99939
1 1 1 1
m 1085
Y
LEAK RATE Leak Rate, gpm 10.85EFPN 11.7EFPY 13.33EFPY
1.80E-07 0.112 0.9978 1 3.20E-07 0.1148 0.998 1 5.60E-07 0.1189 0.998 1 1.00E-06 0.1239 0.998 1 1.80E-06 0.1297 0.9981 1 3.20E-06 0.1376 0.9981 1 5.60E-06 0.1484 0.9982 1 1.OOE-05 0.1644 0.9983 1 1.80E-05 0.1811 0.9986 1 3.20E-05 0.2044 0.9988 1 5.60E-05 0.2344 0.9988 1 1.OOE-04 0.2728 0.9989 1 1.80E-04 0.3229 0.999 1 3.20E-04 0.3844 0.9991 1 5.60E-04 0.4572 0.9993 1 1.OOE-03 0.5466 0.9996 1 1.80E-03 0.6394 0.9996 1 3.20E-03 0.7246 0.9998 1 5.60E-03 0.8055 0.9999 1 1.OOE-02 0.8679 1 1 1.80E-02 0.9121 1 1 3.20E-02 0.9418 1 1 5.60E-02 0.962 1 1 1.OOE-01 0.9746 1 1 1.80E-01 0.9827 1 1 3.20E-01 0.986 1 1 5.60E-01 0.9885 1 1
1.OOE+O0 0.9898 1 1 1.80E+00 0.9907 1 1 3.20E+00 0.9923 1 1 5.60E+00 0.994 1 1 1.00E+01 0.9955 1 1 1.80E+01 0.9971 1 1 3.20E+01 0.998 1 1 5.60E+01 0.9988 1 1 I.OOE+02 0.999 1 1 1.80E+02 0.9994 1 1 3.20E+02 0.9998 1 1 5.60E+02 1 1 1 I.00E+03 1 1 1
Burst Pressure. Psi.4
BURST PRESSURE 10.85EFPN 11.7EFPY 13.33EFPY
250 500 750
1000 1250 1500 1750 2000 2250 2500 2750 3000 3250
3500 3750 4000 4250 4500 4750 5000 5250 5500 5750 6000 6250 6500 6750 7000 7250 7500 7750 8000 8250 8500 8750 9000 9250 9500 9750
10000 10250 10500 10750 11000 11250 11500 11750 12000 12250 12500
0 0 0 0 0 0 0 0 0
0.0001 0.0001 0.0003 0.0005 0.001
0.0019 0.0032 0.0053 0.0085 0.0131 0.0196 0.0283 0.0397 0.0538 0.071
0.0914 0.1148 0.1417 0.1716 0.2044 0.2398 0.2778 0.3185 0.3613 0.4059 0.4527 0.5014 0.5521 0.6042 0.6581 0.7135 0.7706 0.8277 0.8798 0.9248 0.9592 0.9815 0.9935 0.9989
1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0001 0.0002 0.0002 0.0004 0.0005 0.0009 0.0013 0.0021 0.0034 0.0056 0.0096 0.0169 0.0298 0.0519 0.0877 0.1406 0.2118 0.3007 0.404
0.5179 0.6364 0.7461 0.8414 0.9137 0.9608 0.9861 0.9976
1 1
"
It
0 0 0 0 0 0
*0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0002 0.0006 0.0016 0.0042 0.0104 0. 0232 0.0463 0.0834 0. 1361 0.2045 0.2862 0.3779 0.4769 0.5803 0.6845 0. 7801 0.8625 0.9253 0.9661 0.9881 0.9979
I 1
Appendix 7
Circumferential Degradation at the Top of the Tubesheet
Circumferential degradation at expansion transitions at the top of the tubesheet has been -observed at SONGS Unit 2 at EOC 6, EOC 7, EOC 8 and EOC 9 inspections. Both ID and OD degradation has been observed. Use of the Plus Point probe at EOC-8 rather than the previous RPC pancake probe led to an inspection transient which was included in that simulation model. The measure of severity for circumferential degradation is the percent degraded area of the tube annular cross section. PDA values at EOC 8 and EOC 9 were obtained following an EPRI voltage normalization procedure. As in the case of the top of the tubesheet axial cracking, both ID and OD circumferential cracking was considered together using an appropriately conservative growth rate distribution.
Inputs:
Inspection POD Growth Initiation Sizing Error
Data from C _j >o a) C ) 0 .2 0 Outages _ co 0) 0
(0 C lO Cl LL OC
8,9 & 10
OR f•1i C v: e46 e•, i z z z o• •, o o
VERSION CircMultila.exe 10/4/98
Indications Observed SG 88189
Mechanism 2C8 I 2C9 2M9 2C10 TTS CIRC 12-15 62-93 N/A 41-63
Simulation Predictions Mean Standard Deviation
Mechanism 2C8 209 2M9 2C10 2C8 2C9 2M9 2C10 II • l ....
I 'Z t t- I N/A 62 3 1 9 N/A 8
SOUTHERN CALIFORNIA EDISON
Input File Name
# Sims # Tubes Sites/Tube
SLB NOP Leak Limit
Tube Wall Mean Strength Max Strength Young's Modulus
D:\O PCON_050798\CircMulti\ttscirc.out
20000 9350 1
2.575 1.46 0.01
Initiation Slope Initiation Scale Initiation Setback
Mean Error Error Std Dev Max Error
Tube OD Strength Std Dev Min Strength
0.048 132.51 143 28700000
Bin Top 0 0.02 0.04 0.06 0.08 0.1 0.12 0.16 0.22 0.25
Cycle, EFPY 8.62 10.09 11.66 13.33
Fraction Observed 0.422 0.533 0.6 0.71 0.8 0.844 0.911 0.956 0.978 1
Fraction Inspct. 0.2 1.0 1.0 1.0
Repair Limit -99.0 -99.0 -99.0 -99.0
POD Fit L/L L/L UL L/L
POD Intercept 2.07 0.885 0.885 0.885
54 2.4 0
0 0.13 1
0.75 5.73 123
POD Slope -2.75 -2.48 -2.48 -2.48
OUTPUT FILE:"D:\OPCON 050798\CircMulti~ttscirc.out"
Cycle, EFPY 8.62 10.09 11.66 13.33 POL at SLB 0.9943 0.9574 0.4423 0.4798 POL >Limit at SLB 0.9782 0.8649 0.1611 0.1748 POL >Limit at NOP 0.8887 0.5333 0.0221 0.015 95/95 Leak at SLB 0.289 0.105 0.018 0.017
# Sims w/Bursts 15334 1958 50 4 POB at SLB (95%) 0.7716 0.1014 0.0032 0.0005 POB at 3DP 0.8863 0.2933 0.0101 0.0024
Initiated 113.72 51.53 68.25 87.29 In Service 113.72 153.25 142.15 167.81 Mean # Detected 7.73 79.24 61.62 70.99 Std Dev, # Detected 2.81 8.81 7.75 8.06 Mean # Known In Service 7.73 79.24 61.62 70.99 Std Dev, # Known In Servic 2.81 8.81 7.75 8.06 Cumulative # Detected, Me 7.73 86.97 148.59 219.58 Cumulative # Detected, Stc 2.81 9.25 12.09 14.29 Mean # Plugged 11.99 79.34 61.64 71.02 Std Dev, # Plugged 3.53 8.82 7.75 8.06 Cumulative # Plugged, Mei 11.99 91.34 152.98 224 Cumulative # Plugged, Std 3.53 9.45 12.23 14.37 Mean Maximum Depth 1.103 0.68 0.433 0.426 Std Dev, Maximum Depth 0.307 0.127 0.091 0.06
TRUE Depth, % Through Wall
I7
TRUE DEPTH 8.62 10.09 11.66 13.33
5 10 15 20 25 30 35 40 45 50 55 60 65
70 75 80 85 90 95
100
,p
69.25 10.64 7.37 5.53 4.31 3.39 2.62 2.05 1.61 1.28 1.01 0.81 0.67 0.55 0.44 0.37 0.29 0.24 0.19
1
DETECTED Depth, % Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
DETECTED DEPTH 8.62 10.09 11.66 13.33 0.89 14.85 16.02 18.88
1.2 17.52 16.46 18.58 1.05 12.98 11.16 13.04 0.87 10.22 7.95 9.1 0.72 6.54 4.08 4.5 0.59 4.54 2.01 2.54 0.46 4.03 1.52 1.49 0.37 2.89 1.62 1.61 0.29 1.75 0.37 0.84 0.24 1.22 0.18 0.16 0.19 0.87 0.09 0.07 0.15 0.61 0.05 0.03 0.13 0.42 0.03 0.01
0.1 0.3 0.02 0.01 0.09 0.2 0.01 0 0.07 0.13 0 0 0.06 0.09 0 0 0.05 0.04 0 0 0.04 0.02 0 0 0.19 0.03 0 0
78.98 22.64 15.14 11.39
7.11 4.85 4.26 3.03 1.82 1.27
0.9 0.63 0.43 0.31
0.2 0.13 0.09 0.04 0.03 0.03
88.07 21.22
13 8.86 4.44 2.15 1.61 1.7
0.39 0.18 0.1
0.05 0.03 0.02 0.01
0 0 0 0 0
105.68 23.96 15.22 10.11 4.89 2.71 1.58 1.69 0.88 0.17 0.07 0.03 0.01 0.01
0 0 0 0 0 0
MEASURED Depth, % Throuoh Wall% Throuah A 11
MEASURED DEPTH 8.62 10.09 11.66 13.33
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
TRUE Depth, % Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
I-.--
TRUE DEPTH 8.62 10.09 11.66 13.33
0.60949 0.70313
0.768 0.81667 0.8546
.0.88444 0.9075
0.92554 0.93971 0.95098 0.95987
0.967 0.97289 0.97773 0.98161 0.98486 0.98741 0.98953
0.9912 1
0.51527 0.66297 0.76174 0.83605 0.88244 0.91408 0.94187 0.96164 0.97351 0.9818
0.98767 0.99178 0.99459 0.99661 0.99791 0.99876 0.99935 0.99961 0.9998
1
0.62095 0.63278 0.77057 0.77624 0.86223 0.86737
0.9247 0.92791 0.956 0.95719
0.97116 0.97341 0.98251 0.98288 0.9945 0.99299
0.99725 0.99826 0.99852 0.99928 0.99922 0.9997 0.99958 0.99988 0.99979 0.99994 0.99993 1
1 1 1 1 1 1 1 1 1 1 1 1
1.57 0.66 0.72 0.73 0.68
0.6 0.52 0.42 0.35 0.28 0.23 0.18 0.15
0.13 0.1
0.08 0.07 0.05 0.05 0.21
22.29 8.69 8.95 8.55 7.45 6.13 4.77
3.6 2.63
1.9 1.33 0.95 0.66 0.46 0.3
0.21 0.14 0.1
0.06 0.08
21.27 7.77 7.71 6.94 5.67 4.27 2.98 1.99 1.25 0.76 0.44 0.25 0.13 0.07 0.03 0.02 0.01
0 0 0
I24.54
8.9 8.9
8 6.52 4.9
3.43 2.28 1.45 0.88 0.52 0.28 0.14
0.07 0.03 0.01 0.01
0 0 0
DETECTED Depth, % Through Wall
DETECTED DEPTH 8.62 10.09 11.66 13.338 20 1.... 1...
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
MEASURED Depth, % Through Wall
5 10 15
20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
MEASURED DEPTH 8.62 10.09 11.66 13.33
0.2018 0.28663 0.37918 0.47301 0.56041 0.63753 0.70437 0.75835 0.80334 0.83933 0.86889 0.89203 0.91131 0.92802 0.94087 0.95116 0.96015 0.96658 0.97301
1
0.28126 0.34552 0.34632 0.39091 0.47173 0.47192 0.50385 0.59698 0.59752 0.61174 0.70971 0.71041 0.70574 0.80182 0.80243 0.78309 0.87118 0.87158 0.84328 0.91959 0.91998 0.88871 0.95192 0.95216 0.92189 0.97222 0.97262 0.94587 0.98457 0.98504 0.96265 0.99172 0.99238 0.97464 0.99578 0.99633 0.98297 0.99789 0.99831 0.98877 0.99903 0.99929 0.99256 0.99951 0.99972 0.99521 0.99984 0.99986 0.99697 1 1 0.99823 1 1 0.99899 1 1
1 1 1
0.11484 0.26968 0.40516 0.51742 0.61032 0.68645 0.74581 0.79355 0.83097 0.86194 0.88645 0.90581 0.92258 0.93548 0.9471
0.95613 0.96387 0.97032 0.97548
1
0. 18738 0.40845 0.57224
0.7012 0.78372 0.84101 0.89186 0.92833 0.95041 0.9658
0.97678 0.98448 0.98978 0.99356 0.99609 0.99773 0.99886 0.99937 0.99962
1
0.26019 0.52753 0.70879 0.83791 0.90417 0.93682 0.96151 0.98782 0.99383 0.99675 0.99821 0.99903 0.99951 0.99984
1 1 1 1 1 1
0.26644 0.52865 0.71267
0.8411 0.9046
0.94045 0.96147 0.98419
0.99605 0.99831 0.99929 0.99972 0.99986
1 1 1 1 1 1 1
T
Leak Rate, gpm.4
LEAK RATE 8.62EFPY 10.09EFP) 11.66EFP'N 13.33EFPY
1.80E-07 3.20E-07 5.60E-07 I.OOE-06 1.80E-06 3.20E-06 5.60E-06 1.OOE-05 1.80E-05 3.20E-05 5.60E-05 I.OOE-04 1.80E-04 3.20E-04 5.60E-04 I .OOE-03 1.80E-03 3.20E-03 5.60E-03 I.OOE-02 1.80E-02 3.20E-02 5.60E-02 I.OOE-01 1.80E-01 3.20E-01 5.60E-01 I.OOE+00 1.80E+00 3.20E+00 5.60E+00 I.00E+01 1.80E+01 3.20E+01 5.60E+01 1.OOE+02 1.80E+02 3.20E+02 5.60E+02 I .OOE+03
0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0057 0.0218 0.0693 0.1545 0.3479 0.6221 0.8527 0.9618 0.9925 0.9993
1 1 I 1 I I 1 1 1 I I 1
0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.0426 0.1351 0.3296 0.5691 0.8117 0.9456 0.989
0.9983 0.9999
1 1 I I I 1 1 1 1 1 1 1 1
0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.5577 0.8389 0.9517 0.9851 0.9955 0.9989 0.9997
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.5202 0.8252 0.9601 0.9913 0.9984 0.9998
1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1
Burst Pressure, psi 250 500
750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000 5250 5500 5750 6000 6250 6500 6750 7000 7250 7500 7750 8000 8250 8500 8750 900O 9250 9500 9750
10000 10250 10500 10750 11000 11250 11500 11750 12000 12250 12500 12750 13000 13250 13500 13750 14000 14250 14500 14750 15000 15250 15500 15750 16000 16250 16500 16750 17000 17250 17500 17750 1800 18250 18500 18750 19000 19250 19500 19750 20000
BURST PRESSURE 18.62EFPY 10.0OEFPI 11.66EFP) 13.33EFP'g
0.0078 0.0082 0.0087 0.0091 0.0096 0.0102 0.0107 0.0113
0.012 0.0127 0.0133 0.0141 0.0149 0.0157 0.0165 0.0175 0.0184 0.0194 0.0205 0.0216 0.0228 0.0241 0.0253 0.0267 0.0281 0.0296 0.0311 0.0328 0.0344 0.0362
0.038 0.04
0.042 0.0442
,0.0464 0.0487 0.0511 0.0538 0.0565 0.0594 0.0623 0.0656 0.0689 0.0723
0.076 0.0799 0.0841 0.0882 0.0927 0.0974 0.1024 0.1076
0.113 0.1188 0.1248
0.131 0.1377 0.1447 0.1518 0.1594 0.1673 0.1757 0.1844 0.1935
0.203 0.213
0.2235 0.2346 0.2461 0.2584 0.2714 0.2851
0.3 0.3158 0.3329 0.3516 0.3722
0.418 0.4563
1
0.0001 0.0001 0.0002 0.0002 0.0002 0.0003 0.0004 0.0004 0.0005 0.0006 0.0008 0.0009 0.0011 0.0013 0.0016 0.0018 0.0021 0.0024 O.0028 0.0032 0.0036 0.0041 0.0046 0.0052 0.0058 0.0065 0.0073 0.0081
0.009 0.01
0.0111 0.0123 0.0135 0.0149 0.0164
0.018 0.0198 0.0217 0.0237 0.026
0.0284 0.031
0.0338 0.0368 0.0403
0.044 0.0484 0.0534 0.0588 0.0645 0.0705 0.0768 0.083
0.0894 0.0959 0.1026 0.1099 0.1177 0.1259 0.1348 0.1445 0.1551 0.1668 0.1795 0.1931 0.2077 0.2234 0.2402 0.258
0.2772 0.2976 0.3195 0.3428 0.3673 0.3934 0.4215 0.4516 0.4995 0.541
1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0002 0.0002 0.0002 0.0003 0.0003 0.0004 0.0004 0.0005 0.0006 0.0007 0.0008 0.0009 0.0011 0.0013 0.0015 0.0017
0.002 0.0023 0.0027 0.0032 0.0037 0.0046 0.0057 0.0072 0.0093 0.0117 0.0143
0.017 0.01 97 0.0224 0.025
0.0277 0.0305 0.0335
0.037 0.0409 0.0453 0.0505 0.0563 0.0631
0.071 0.0798 0.0897 0.1006 0.1 128 0.1264 0.1409 0.1569 0. 1743 0.1934 0.2142 0.2367 0.2611 0.2877 0.3168 0.3488 0.4027 0.4498
1
0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0002 0.0002 0.0003 0.0003 0.0004 0.0005 0.0006 0.0008 0.0009 0.0011 0.0014 0.0017 0.0023 0.0032 0.0045 0.0062 0.0082 0.0105 0.0127 0.015
0.0171 0.0192 0.0213 0.0235 0.0258 0.0284 0.0313 0.0347 0.0386 0.0431 0.0482 0.0543 0.0612 0.069
0.0778 0.0876 0.0984 0.1104 0.1234 0.1375 0.1529 0.1699 0.1886 0.2088 0.2307 0.2544 0.2801 0.3084 0.3397 0.3934 0.4399
1
Appendix 8 Axial Degradation at the Top of the Tubesheet - Sludge Pile
Axial degradation near expansion transitions at the top of the tubesheet was first detected at SONGS Unit 2 in the inspection at EOC-8. Crack lengths evaluated from the response of the Plus Point probe substantially overstate the crack
length relative to the structurally significant crack length. Even when conservatively equating the structurally significant crack length to the Plus Point crack length, the severity of the axial top of the tubesheet degradation is mild. Very few of the indications are long enough to challenge the SLB burst pressure
with the bounding assumption of 100% throughwall cracking.
Inputs:
Inspection POD Growth Initiation Sizing Error
Data from 0. ® 4) 0 ) CL - 0 C 0 Outages E o (n CO
U) LL C/3CJ
9, & 10
0i C4~0~- e 0 0~
VERSION AxMultilb.exe 5/5/98
Indications Observed SG 88189
Mechanism 2C8 2C9 2M9 2010 TTS OD AXIAL 60-61 N/A 14-15
Simulation Predictions Mean Standard Deviation Mechanism 2C8 2C9 I 2M9 I 2C10 2C8 2C9 2M9 2010
TTS OD AXIAL 53 N/A 21 7 N/A 5
SOUTHERN CALIFORNIA EDISON
D:\OPCON_050798\AxMulti\AX_S U B\odslg 1 .out
# Sims # Tubes Sites/Tube
SLB NOP Leak Limit
20000 9350 1
2.575 1.46 0.01
Tube Wall Mean Strength Max Strength Young's Modulus
Mean Ln(Growth Rate) Max Growth Rate
Initiation Slope 1.7 Initiation Scale 210 Initiation Setback 4
Mean Error 0 Error Std Dev 0.0375 Max Error 100
Tube OD 0.75 Strength Std Dev 5.73 Min Strength 123
Std Dev of Mean 0.3 Fraction Zero Growth 0
0.048 132.51 143 28700000
1.4 100
Cycle, EFPY 10.07 11.66 13.33
Fraction Inspct. 1.0 1.0 1.0
Repair Limit -99.0 -99.0 -99.0
POD Fit UL L/L UL
POD Intercept 9.25 9.25 9.25
POD Slope -7.26 -7.26 -7.26
Input File Name
OUTPUT FILE:"D:\OPCON 050798\AxMulti\odslgq1.out"
Cycle, EFPY 10.07 11.66 13.33 POL at SLB 0.2725 0.0039 0.0001 POL >Limit at SLB 0.0539 0.0005 0 POL >Limit at NOP 0.0311 0.0002 0 95195 Leak at SLB, NOP 0.013 0 0
# Sims wlBursts 2 0 0 POB at SLB (95%) 0.0003 0.0001 0.0001 POB at 3DP 0.0205 0.0003 0
Initiated 94.12 18.68 21.07 In Service 94.12 59.84 60.15 Mean # Detected 52.96 20.76 18.75 Std Dev, # Detected 7.16 4.68 4.33 Mean # Known In Service 52.96 20.76 18.75 Std Dev, # Known In Servic 7.16 4.68 4.33 Cumulative # Detected, Me 52.96 73.72 92.48 Cumulative # Detected, Stc 7.16 8.36 9.34 Mean # Plugged 52.96 20.76 18.75 Std Dev, # Plugged 7.16 4.68 4.33 Cumulative # Plugged, Me, 52.96 73.72 92.48 Cumulative # Plugged, Std 7.16 8.36 9.34 Mean Maximum Depth 0.701 0.418 0.325 Std Dev, Maximum Depth 0.114 0.091 0.058
TRUE Depth, % Throuah Wall
"TRUE
DETECTED Depth, % Throuah Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
DETECTED DEPTH 10.07 11.66 13.33
0.11 1.51 4.43 6.85 7.77 7.68 6.84 5.56 4.16
2.9 1.91 1.19 0.74
0.45
0.25 0.15 0.09 0.05 0.03 0.04
0.11 1.51 4.54 5.55 4.05 2.37 1.29 0.71 0.38
0.2 0.1
0.05 0.02 0.01 0.01
0 0 0 0 0
0.12 1.61 4.65 5.84
4 1.73 0.6
0.19 0.07 0.02 0.01
0 0 0 0 0 0 0 0 0
DEPTH 1t V11
% Throuch Wall 1007 11665
10 15 20 25 30o 35 40 45 50 55 60 65 70 75 80 85 9o 95
100
14.05 13.05 11.92 10.86 9.83 8.77 7.41 5.85 4.31 2.98 1.95 1.21 0.75
0.45 0.25 0.15 0.09 0.05 0.03 0.04
14.89 12.97 12.29 8.93 5.15 2.72
1.4 0.75 0.39 0.2 0.1
0.05 0.02 0.01 0.01
0 0 0 0 0
16.13 13.87 12.59 9.41 5.12 1.98 0.66
0.2 0.07 0.02 0.01
0 0 0 0 0 0 0 0 0
MEASURED Depth, % Through Wall
MEASURED DEPTH 10.07 11.66 13.33
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
TRUE Depth, % Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65
70 75 80 85 90 95
100
TRUE DEPTH 10.07 11.66 13.33
0.14947 0.2883
0.41511 0.53064 0.63521 0.72851 0.80734 0.86957 0.91543 0.94713 0.96787 0.98074 0.98872
0.99351 0.99617 0.99777 0.99872 0.99926 0.99957
1
0.24866 0.46526 0.67051 0.81964 0.90564 0.95107 0.97445 0.98697 0.99349 0.99683 0.9985
0.99933 0.99967 0.99983
1 1 1 1 1 1
0.26856 0.4995
0.70912 0.8658
0.95105 0.98402
0.995 0.99833 0.9995
0.99983 1 1 1 1 1 1 1 1 1 1
0.51 1.91 4.3
6.45 7.49 7.45 6.74 5.51 4.2
2.99 1.98 1.27 0.78
0.48 0.28 0.16
0.1 0.08 0.01 0.03
0.51 1.9
4.02 4.88 3.97 2.54 1.42 0.78 0.42 0.22 0.11 0.06 0.02 0.01 0.01
0 0 0 0 0
0.54 1.99 4.15 5.04 3.88 2.02
0.8 0.27 0.09 0.03 0.01
0 0 0 0 0 0 0 0 0
DETECTED Depth, % Throuah Wall
DETECTED DEPTH 10.07 11.66 13.33
MEASURED Depth, % Throuqh Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
MEASURED DEPTH 10.07 11.66 13.33
0.00967 0.0459
0. 12747 0.24981 0.39188 0.53319 0.66104 0.76555 0.84522 0.90193 0.93949 0.96358 0.97838
0.98748 0.99279 0.99583 0.99772 0.99924 0.99943
1
0.02444 0.11548 0.3081
0.54193 0.73215 0.85386
0.9219 0.95927
0.9794 0.98994 0.99521 0.99808 0.99904
0.99952 1 1 1 1 1 1
0.02869 0.13443 0.35494 0.62274 0.82891 0.93624 0.97875 0.99309 0.99787 0.99947
1 1 1 1 1 1 1 1 1 I
y ....
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
0.00209 0.03073 0.11478 0.24474 0.39215 0.53785 0.66762
0.7731 0.85202 0.90704 0.94327 0.96585 0.97989
0.98843 0.99317 0.99602 0.99772 0.99867 0.99924
1
0.00526 0.07751 0.29474 0.56029 0.75407 0.86746 0.92919 0.96316 0.98134 0.99091 0.99569 0.99809 0.99904 0.99952
1 1 1 1 1 1
0.00637 0.09183 0.33864 0.64862 0.86093 0.95276 0.98461 0.99469 0.99841 0.99947
1 1 1
1 1 1 1 1 1 1
Leak Rate. aomLEAK RATE
10.07EFPN 11.66EFPt 13.33EFPY1.80E-07 3.20E-07 5.60E-07 1.00E-06 1.80E-06 3.20E-06 5.60E-06 I.OOE-05 1.80E-05 3.20E-05 5.60E-05 I.OOE-04 1.80E-04 3.20E-04 6.60E-04 I.OOE-03 1.80E-03 3.20E-03 5.60E-03 I.OOE-02 1.80E-02 3.20E-02 5.60E-02 1.OOE-01 1.80E-01 3.20E-01 5.60E-01 I.00E+00 1.80E+00 3.20E+00 5.60E+00 1.OOE+01 1.80E+01 3.20E+01 5.60E+01 I.OOE+02 1.80E+02 3.20E+02 5.60E+02 1.OOE+03
0.7346 0.7362 0.7386 0.7413 0.7454 0.7497 0.7558 0.7617 0.771
0.7802 0.7906
0.804 0.8201
0.839 0.8585 0.8781 0.8962 0.9149 0.9324 0.9462 0.9584 0.9679 0.9748 0.9827 0.9881 0.9917 0.9938 0.9954 0.9968
0.998 0.9989 0.9993 0.9995 0.9998 0.9999
1 1 1 1 1
0.9963 0.9964 0.9964 0.9965 0.9965 0.9966 0.9968 0.9968
0.997 0.997
0.9972 0.9977
0.998
0.9982 0.9987 0.9989 0.999
0.9992 0.9992 0.9995 0.9997 0.9998 0.9999 0.9999 0.9999 0.9999
1 1 1 1 1 1 1 1 1 1 1 1 1 I
Burst Pressure, psi 250 500 750
1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000 5250 5500 5750 6000 6250 6500 6750 7000 7250 7500 7750 8000 8250 8500 8750 9000 9250 9500 9750
10000 10250 10500 10750 11000 11250 11500 11750 12000 12250 12500 12750 13000 13250
BURST PRESSURE 10.07EFPY 11.66EFPN 13.33EFPY
0 0 0 0 0 0
0.0001 0.0001 0.0001 0.0002 0.0002 0.0003 0.0004 0.0006 0.0008 0.001
0.0014 0.002
0.0028 0.0038 0.0053 0.0074
0.01 0.0138 0.0189 0.0257 0.0346 0.0466 0.062
0.0815 0.1059 0.1356 0.1717 0.2137 0.2621 0.3163 0.3759 0.4402 0.5093 0.5837 0.6625 0.7438 0.8198 0.8865 0.938
0.9715 0.99
0.9982 1 1 1 1 1
0 0 0 *0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0001 0.0001 0.0002 0.0003 0.0005 0.0008 0.0013
0.002 0.003
0.0046 0.0071 0.0107 0.0161 0.0242 0.0364 0.0546 0.0817 0.1217 0.178
0.2539 0.3491 0.4623 0.5868
0.707 0.8146
0.898 0.953
0.9832 0.997
1 1 1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0001 0.0003 0.0005 0.0009 0.0017
0.0064 0.0125 0.0244 0.0458 0.0814 0.1364 0.2129 0.31 07 0.4286 0.5594 0.6863 0.8005
0.89 0.9493 0.9819 0.9968
1 1 1 1 1
Appendix 9
Tube Wear
Tube wear was modeled in the current assessment. This degradation mode has
not been modeled in earlier operational assessments. The method for modeling
included the use of a plugging limit - this is different from the previous, "crack
like" mechanisms which are treated as "plug on detection".
The rate of new tube wear indications has tended upward in recent outages.
Inputs:
Inspection POD Growth Initiation Sizing Error
- - ,--> L - > C. 0 Data from (D --) ) X
-- CO CO °rS
8, 9, 9M, & 10
C14 Cý 0;0 N , 0 'T- 0 0 c3 x-- 0• 0 0 .
VERSION AxMultilb.exe 5/5/98
Indications Observed SG 88189
Mechanism 2C8 2C9 2M9 2C10 WEAR >30% 0-1 2-3 5-14 13-19
Simulation Predictions Mean Standard Deviation
Mechanism 2C8 2C9 2M9 2C10 2C8 2C9 2M9 2C10 WEAR >30% 16 18 13 17 4 4 4 5
SOUTHERN CALIFORNIA EDISON
D:\OPCON_050798\AxMulti\AX_SUB\wear.out
# Sims # Tubes Sites/Tube
SLB NOP Leak Limit
Tube Wall Mean Strength Max Strength Young's Modulus
Mean Ln(Growth Rate) Max Growth Rate
20000 9350 1
2.575 1.46 0.01
Initiation Slope Initiation Scale Initiation Setback
Mean Error Error Std Dev Max Error
Tube OD Strength Std Dev Min Strength
0.048 132.51 143 28700000
0.6 100
3 13 0
0 0.04 100
0.75 5.73 123
Std Dev of Mean 0.5 Fraction Zero Growth 0
Cycle, EFPY 8.62 10.07 10.85 11.66 13.33
Fraction Inspct. 1.0 1.0 1.0 1.0 1.0
Repair Limit 0.3 0.3 0.3 0.3 0.3
POD Fit L/L L/L L/L L/L L/L
POD Intercept 24.0 24.0 24.0 24.0 24.0
POD Slope -20.0 -20.0 -20.0 -20.0 -20.0
Input File Name
OUTPUT FILE:"D:\OPCON 050798MAxMultihwear.out"
Cycle, EFPY 8.62 10.07 10.85 11.66 13.33 POL at SLB 0.0149 0 0 0 0 POL >Limit at SLB 0.0024 0 0 0 0 POL >LImit at NOP 0.0014 0. 0 0 0 95/95 Leak at SLB, NOP 0 0 0 0 0
# Sims wlBursts 0 0 0 0 0 POB at SLB (95%) 0.0001 0.0001 0.0001 0.0001 0.0001 POB at 3DP 0.0012 0 0 0 0
Initiated 2365.81 1111.69 645.34 683.52 1362.38 In Service 2365.81 3465.76 4098.99 4769.66 6115.36 Mean # Detected 176.45 208.7 211.96 274.95 734.39 Std Dev, # Detected 12.87 14.17 14.05 16.72 25.45 Mean # Known In Service 176.45 373.42 573.26 835.37 1553.08 Std Dev, # Known In Servic 12.87 18.66 22.82 27.37 35.21 Cumulative # Detected, Me 176.45 385.15 597.11 872.06 1606.45 Cumulative # Detected, Stc 12.87 18.84 22.92 27.64 35.35 Mean # Plugged 11.74 12.12 12.84 16.68 53.04 Std Dev, # Plugged 3.25 3.4 3.59 4.08 7.13 Cumulative # Plugged, Mei 11.74 23.86 36.69 53.38 106.42 Cumulative # Plugged, Std 3.25 4.76 5.96 7.4 10.25 Mean Maximum Depth 0.46 0.329 0.308 0.305 0.349 Std Dev, Maximum Depth 0.095 0.025 0.017 0.016 0.026
TRUE Depth, % Throuah Wall
TRUE DEPTH 8.62 10.07 10.85 11.66 13.33
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
1543.04 553.25 175.56 58.02 20.63 7.87
3.2 1.38 0.63
0.3 0.14 0.07 0.04 0.02 0.01 0.01
0 0 0 0
1879.92 1035.03 372.93 121.32 40.24 11.93
2.15 0.19 0.01
0 0 0 0 0 0 0 0 0 0 0
2007.36 1304.19 538.75 177.47
56.1 12.87
1.05 0.02
0 0 0 0 0 0 0 0 0 0 0 0
DETECTED Depth, % Throuqh Wall
5 10 15 20 25 30 35 40 45 50 55 6o 65 70 75 80 85 90 95
100
DETECTED DEPTH 8.62 10.07 10.85 11.660.04
11.19 76.56 53.83 20.47
7.86 3.19 1.38 0.63 0.3
0.14 0.07 0.04 0.02 0.01 0.01
0 0 0 0
0.06 24.14
176.95 117.12 40.21 11.92 2.15 0.19 0.01
0 0 0 0 0 0 0 0 0 0 0
0.07 37.91
288.56 175.04 56.09 12.87
1.05 0.02
0 0 0 0 0 0 0 0 0 0 0 0
0.08 49.52 423.9
261.35 81.73 16.69 0.93 0.01
0 0 0 0 0 0 0 0 0 0 0 0
13.330.07 55.6
667.73 567.43 201.12
52.51 6.74 0.47 0.04 0.01
0 0 0 0 0 0 0 0 0 0
2093.91 1547.37 763.94 264.05
81.73 16.69 0.93 0.01
0 0 0 0 0 0 0 0 0 0 0 0
2126.91 1848.11 1293.45 584.43 201.23
52.52 6.74 0.47 0.04 0.01
0 0 0 0 0 0 0 0 0 0
T
MEASURED Depth, % Through Wall
MEASURED DEPTH 8.62 10.07 10.B5 l1_isa•
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
4.68 24.53 52.78 49.7
26.08 10.58
4.2 1.75 0.77 0.36 0.17 0.09 0.05 0.02 0.01 0.01
0 0 0 0
TRUE Depth, % Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
TRUE DEPTH 8.62 10.07 10.85 11.66 13.33
0.65268 0.54275 0.48986 0.4391 0.34788 0.88669 0.84157 0.80813 0.76359 0.650160.96095 0.94923 0.98549 0.98426 0.99422 0.99588 0.99755 0.99932
0.9989 0.99994 0.99948 1 0.99975 1 0.99988 1 0.99994 1 0.99997 1 0.99998 1
0.99999 1 I 1 1 1 1 I 1 1 1 1 1 1
0.9396 0.98291 0.9966
0.99974 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0.92379 0.97916
0.9963 0.9998
1 1 1 1 1 1 1 1 1 1 1 1 1 1
0.86172 0.95731 0.99022 0.99881 0.99991 0.99999
1 1 1 1 1 1 1 1 1 1 1 1
10.39 55.71 119.6
109.49 53.56 18.25 4.76 0.87
0.1 0.01
0 0 0
0 0 0 0 0 0 0
8.62 10.07 10.85 1166 133316.62 89.97
190.41 168.43 77.38 23.46
4.76 0.55 0.03
0 0 0 0 0 0 0 0 0 0 0
23.04 128.88 278.95 249.4
114.02 33.11
6.14 0.62 0.03
0 0 0 0 0 0 0 0 0 0 0
30.53 192.52 473.93 488.25 256.57 86.44 20.12
3.04 0.3
0.03 0 0 0 0 0 0 0 0 0 0
DETECTED Depth,% Through Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
DETECTED DEPTH 8.62 10.07 10.85 11.66
0.00023 0.0639
0.49954 0.80585 0.92233 0.96705 0.98521 0.99306 0.99664 0.99835 0.99915 0.99954 0.99977 0.99989 0.99994
1 1 1 1 1
0.00016 0.06492 0.53964 0.85384 0.96172 0.9937
0.99946 0.99997
1 1 1 I 1 1 1 1 1 1 1 1
0.00012 0.0001 0.06644 0.05946 0.57126 0.5676 0.87749 0.88089 0.97561 0.97887 0.99813 0.99887 0.99997 0.99999
1 1 1 1 1 1 1 1 I I 1 1
1 1 1 1 1 1 1
1 1 1 1 1 1 1
MEASURED Depth, % Throuah Wall
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
100
MEASURED DEPTH 8.62 10.07 10.85 11.66
0.02662 0.16617 0.46644 0.74918 0.89754 0.95773 0.98162 0.99158 0.99596 0.99801 0.99898 0.99949 0.99977 0.99989 0.99994
1 1 1 1 1
0.02787 0.02908 0.17734 0.18647 0.4982 0.51959
0.79195 0.81424 0.93564 0.94962
0.9846 0.99066 0.99737 0.99899
0.9997 0.99995 0.99997 1
1 1 1 1 1 1 1 11 1 1 1 1 1 1
1 1 1 1 1 1 1
13.330.00005 0.03588 0.46619 0.83187 0.96148 0.99532 0.99966 0.99997 0.99999
1 1 1 1 1 1 1 1 1 1 1
0.02762 0.18212 0.51651 0.81549 0.95217 0.99186 0.99922 0.99996
1 1 1 1 I 1 1 1 1 1 1 1
13.330.01967 0. 14374 0.44916 0.76381 0.92916 0.98486 0.99783 0.99979 0.99998
1 1 1 1
1 1 1 1 1 1 1
IY
Leak Rate, gpmLEAK RATE
8.62EFPY 10.07EFPN 10.85EFPN 11.66EFPN 13.33EFPYF-1.80E-07
3.20E-07 5.60E-07 I.OOE-06 1.80E-06 3.20E-06 5.60E-06 I.OOE-05 1.80E-05 3.20E-05 5.60E-05 I.OOE-04 1.80E-04 3.20E-04 5.60E-04 I.OOE-03 1.80E-03 3.20E-03 5.60E-03 1.OOE-02 1.80E-02 3.20E-02 5.60E-02 I.OOE-01 1.80E-01 3.20E-01 5.60E-01 I.OOE+00 1.80E+00 3.20E+00 5.60E+00 I.OOE+01 1.80E+01 3.20E+01 5.60E+01 1.OOE+02 1.80E+02 3.20E+02 5.60E+02 I.OOE+03
0.9857 0.9859 0.986
0.9863 0.9866 0.9869 0.9872 0.9875 0.988
0.9886 0.9892 0.9901 0.9911 0.9921 0.9928
0.994 0.9949 0.996
0.9967
0.9976 0.9981 0.9986 0.9988 0.9991 0.9993 0.9995 0.9997 0.9998 0.9998
1 1 1 1 1 1 1 1 1 1 1
Burst Pressure ',psi
250 500 750
1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000 5250 5500 5750 6000 6250 6500 6750 7000 7250 7500 7750 8000 8250 8500 8750 9000 9250 9500 9750
10000 10250 10500 10750 11000 11250 11500 11750 12000 12250 12500
BURST PRESSURE 8.62EFPY 10.07EFPN10.85EFP' 11.66EFP' 13.33EFPY
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0001 0.0001 0.0002 0.0003 0.0004 0.0007 0.0011 0.0019 0.0032 0.0055 0.0098
0.018 0.0344
0.068 0.1374 0.2605 0.4126 0.5869 0.7504 0.8745 0.9509 0.9901
1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0002 0.0007 0.0019 0.0045
0.01 0.0213 0.0446
0.091 0.1759 0.3087 0.4661 0.6352 0.7858 0.8956 0.9609 0.9921
1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0005 0.0016 0.0044 0.0108 0.0244 0.0526 0.1068
0.2 0.3375 0.4962 0.6613 0.8043 0.9063 0.9655 0.9934
1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0.0001 0.0005 0.0018 0.0052 0.0132 0.0303 0.0649 0.1277 0.2293 0.3707 0.5291 0.6883 0.8225 0.9162 0.9696 0.9942
1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 .0 0
0.0001 0.0005 0.0016 0.0045 0.0115 0.0265 0.0559 0.1077 0.1892 0.3037 0.448
0.5983 0.7404 0.8551 0.9327 0.9758 0.9954
1 1
top related