steam generator tube integrity operational …the value that has been calculated is 0.028 gallon per...

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

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.


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.


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



* 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


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.


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.


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.


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).


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


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)


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.


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


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.


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


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.


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


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


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


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


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


(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.


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.


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


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



* 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

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.


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.


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


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:


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 ,


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.


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)


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


Figure A1.3 Idealized Leakage Crack Profile After Throughwall Penetration

L leak

tr


]

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


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


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.


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


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


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.


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:


* 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


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.


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.


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.


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


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


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


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


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


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.


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.


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.


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


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


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:


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 ,


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


D:\OPCON_050798\AxMulti\idegg.out


SLB NOP Leak Limit

20000 9350 1

2.575 1.46 0.01



Initiation Slope 4.9 Initiation Scale 34 Initiation Setback 0

Mean Error 0 Error Std Dev 0.2 Max Error I



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



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


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


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


D:\OPCON_050798\AxMulti\odfs36.out


SLB NOP Leak Limit

20000 9350 1

2.575 1.46 0.01




Mean Error 0 Error Std Dev 0.2 Max Error 1



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



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


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


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


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:


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


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


Input File Name


SLB NOP Leak Limit


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


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


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


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 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


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:


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~



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


D:\OPCON_050798\AxMulti\AX_S U B\odslg 1 .out


SLB NOP Leak Limit

20000 9350 1

2.575 1.46 0.01




Mean Error 0 Error Std Dev 0.0375 Max Error 100



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

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



5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

100


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


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:


- - ,--> 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 .



Mechanism 2C8 2C9 2M9 2C10 WEAR >30% 0-1 2-3 5-14 13-19


Mechanism 2C8 2C9 2M9 2C10 2C8 2C9 2M9 2C10 WEAR >30% 16 18 13 17 4 4 4 5


D:\OPCON_050798\AxMulti\AX_SUB\wear.out


SLB NOP Leak Limit



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


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 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 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


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


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

steam generator tube integrity operational …the value that has been calculated is 0.028 gallon per...

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