davis-besse nuclear power station reactor vessel incore nozzles
TRANSCRIPT
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Davis-Besse Nuclear Power Station
Reactor Vessel Incore Nozzles
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Opening Remarks . . . . . . . . . . ....Gary Leidich
Reactor Vessel Incore Nozzles. Bob Schrauder
Incore Nozzle Configuration
Recent Inspection and Evaluation at Davis-Besse
Actions Prior to Returning the Plant to Service Contingency Repair Concept
FLS Online Leak Monitoring SystemClosing Comments.. Gary Leidich
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Gary Leidich
Executive Vice President - FENOC
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Brief the NRC Staff on the status of the Davis-Besse Reactor Vessel Incore MonitoringInstrumentation Nozzles and future plans
Obtain NRC comments on Davis-Besse approach
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
CEO of FirstEnergy
has set the standard of returning
Davis-Besse
back to service in a safe
and reliable manner.
We must do the job right the
first time and regain theconfidence of our customers,
regulators, and investors in our
nuclear program.
We are committed to meeting
this challenge.
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Reactor HeadReactor HeadResolution PlanResolution Plan
Bob SchrauderBob Schrauder
Program ComplianceProgram Compliance
PlanPlan
Jim PowersJim Powers
Containment HealthContainment Health
Assurance PlanAssurance Plan
Randy FastRandy Fast
Restart Test PlanRestart Test Plan
Randy FastRandy Fast
Management andManagement and
Human PerformanceHuman Performance
Excellence PlanExcellence Plan
Lew MyersLew Myers
System HealthSystem Health
Assurance PlanAssurance Plan
Jim PowersJim Powers
Restart Action PlanRestart Action Plan
LewLew MyersMyers
Restart Overview PanelRestart Overview Panel
Return to Service PlanReturn to Service Plan
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Inspection of the Incore Nozzles is part of the
Containment Health Assurance Building Block in theDavis-Besse Return to Service Plan
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Bob Schrauder
Director - Support Services
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Babcock & Wilcox reactorvessel has 52 Incore Nozzles
Incore nozzles are ~ 1 inchin diameter
Original incore nozzles
fabricated from Alloy 600material Welds - Alloy 182 (stress
relieved)
Incore nozzles modifiedfollowing Oconee 1 1972 HotFunctional Testing Failure
Configuration
Incore Nozzles
at Bottom of Reactor Vessel
(Post-cleaning)
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Repair in Process Completed Repair
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Incore nozzles are exposed to lower temperature (558oF) thanControl Rod Drive Mechanism nozzles (605oF) and are lesssusceptible to stress corrosion cracking
Visual inspections of the incore nozzles have not been routinelyconducted in United States plants
Inspections/testing of incore nozzles at 13 French plants have not
discovered cracking or leaking
Incore Nozzles
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
B&W Current Nozzle ConfigurationEDF Nozzle Configuration
Original Configuration
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Visual Inspections performedas part of the Extent ofCondition Program
Inspection of Bottom of Reactor Vessel
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Inspection results: Boron and rust deposit trails
were observed on the sides and
bottom of the reactor vessel Similar deposits observed on
several incore nozzles
Tape remnants and residueobserved on incore nozzles
No build-up of boric acid or
corrosion products on top ofinsulation
No evidence of wastage on
bottom of reactor vessel
Bottom of Reactor Vessel
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Incore Nozzle #42
Incore Nozzle #45
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
AREAS:
Reactor vessel flow trail and incorenozzle deposits
OBJECTIVE: Determine through chemical analysis
whether flow trails and incore nozzle
deposits had common sourceSAMPLE POPULATION:
2 from flow trails observed on under
reactor vessel sides
12 from incore nozzles
Analysis by Framatome-ANP Incore Nozzle #45
Bottom of Reactor Vessel
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Sample locations ( ) chosenwere nozzles
1
7
3
13
14
18
23
27
35
45
48
46
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Boron and Lithium were higher at several incore nozzle locationsthan in flow trails and more comparable with previously analyzedupper head deposit samples (shown next slide)
Minor species (Uranium, Barium, Thorium, Strontium, & Zirconium)
were higher at several incore nozzle locations than in the flow trails.
However, the lack of activity associated with these species did notsupport reactor coolant as the source
Cobalt (Co60) and Iron (Fe59) were higher in the flow trails than at theincore nozzle locations
Inconsistent concentration gradients along possible flow trail paths
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
NWRustTrail
SEBoricAcidTrail
Nozzle#1
Nozzle#3
Nozzle#7
Nozzle#13
Nozzle#14
Nozzle#18
Nozzle#23
Nozzle#27
Nozzle#35
Nozzle#45
Nozzle#46
Nozzle#48
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
ppm
Comparison of Normalized Boron and Lithium Concentrations
(Flow trails at bottom of reactor head and incore nozzle deposits)
Li
B
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Conclusion
From the results of the analysis,it is inconclusive whether the flow trails at the bottom of the
reactor head and nozzle deposits had a common source
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
FENOC and Framatome-ANP developed inspection plan
Bottom of reactor vessel thoroughly cleaned 9/2002 Planned visual inspections prior to startup:
Raise Reactor Coolant System to normal operating pressure and
temperature (hold for 3-7 days) Potential use of hot optics (visual inspection aid)
Lower temperature and pressure
Perform bare metal reactor vessel visual inspection Perform bare metal reactor vessel visual inspection during the next
scheduled outage
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
0.001
0.010
0.100
1.000
10.000
100.000
1000.000
1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02
Leakage Rate (gpm)
BoricAcidDeposits(in3)
35 Day
28 Day
21 Day
14 Day
10 Day
7 Day
3 Day1 Day
FLUES OPTION 1
FLUES OPTION 2?
Boron Deposit Rate For 2000 ppm Boron Reactor Coolant Leakage(Unchoked Flow) 100% Deposition Rate
For a Given Number of Days
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Inspections will be sufficient to detect leakage
Absence of boric acid will confirm that the deposits found inin 2002 were not from incore nozzle leaks
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Program Objectives Measure leak rate as a function of simulated and/or actual flaw
geometry
Benchmark analytical models for bounding leak ratecalculations
Identify residue deposit chemistry and any volatile chemicals
that exit the crevice
Investigate effect of annulus on leakage rates
Verify methods for detecting very small leaks Visible evidence of boron residue
In-situ monitoring techniques
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Framatome-ANP Hot Leak TestFacility will be used to provide
primary fluid: Tc = 558 F; p = 2200 psig
Primary chemistry (boron &
lithium concentration) Mockup assembly will be
connected to existing hightemperature/ high pressure
supply system Leak rates measured from 10-6
to 0.25 gpm
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Mockup is being designed and built to measure leak ratesthrough simulated (SCC) flaws
Leak rate bounding tests will be conducted for 8 hours each
Final test with a selected leak rate will be run for 5 days
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Insert mechanical plug and
cut existing incore nozzle Deposit 1/2 - 5/8 weld pad
Bore out incore nozzle
remnant into reactor vessel to1 maximum depth
Fit-up replacement nozzle
and complete new weld Remove mechanical plug
1/16" - 1/8" prior to welding
PT
New Alloy 690 Nozzle
New SST Safe End
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
If repairs are necessary, a meeting to discuss final design will beheld with the NRC
10CFR50.55a alternative code (ASME Code Section XI)requests will be necessary to permit implementation of repairs
Alternative code request will be similar to those submitted toNRC for the repair of Control Rod Drive Mechanism nozzles atother plants
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Davis-Besse plans to install FLS Online Leak Monitoring System
Ability to detect and locate leakage with significantly highersensitivity than other available systems
Leak detection system measures the moisture penetrating a sensor
tube Installed or being installed in 12 units in a variety of Europeancountries and Canada
Operational history of 10 years
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Sensor Element
Non-Sensitive Tubing
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DavisDavis--BesseBesse
Nuclear Power StationNuclear Power StationNovember 26, 2002November 26, 2002
Install sensor tubebetween the reactor vessel
insulation and reactorvessel
Simple installation
Expected sensitivity ofapproximately 4E-3 to 2E-2 gpm
System sensitivity isdependent on the airtightness of reactor vesselinsulation
FLS
SENSORS
RVInsulation
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DavisDavis--BesseBesse No ember 26 2002November 26 2002
Gary Leidich
Executive Vice President - FENOC