ML022700361
| ML022700361 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/27/2002 |
| From: | Campbell G, Geisen D, Lockwood D, Moffitt S FirstEnergy Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| -nr, BL-01-001, FOIA/PA-2002-0229 | |
| Download: ML022700361 (17) | |
Text
NRC Bulletin 2001-01, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles" Presenters:
Guy G. Campbell, Vice President - FENOC Ste~ven P. Moffitt, Director 'Technical Services David C. Geisen, Manager - Design Basis Engineering David H. Lockwood, Manager - Regulatory Affairs Steve Fyfitch, Framatome Engineering FENOC a.,
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7c NRC Bulletin 2001-01 response provided
ýV Telephone call received on September r Teleconference on October 3 FENOC 2
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Provide reasonable basis for assurance that Davis-Besse is safe to operate until next refueling outage (March 2002) and should continue 24 month operating cycles
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NRC RulletIin 2551-51 Titled, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles,"
dated August 3, 2001
- Requests that plants provide design information, previous inspection results, and future inspection plans
-z~r Response requirements were based upon plant rankinqgin Susceptibility Model as published in EPRI MIlRP-48.
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$uceiIftIIyModuI EPRI - PWR Materials Reliability Program Response to NRC Bulletin 2001-01 (MPR-48),
1006284, dated August 2001 i
Ranked Davis-Besse as 7th out of 69 plants.
% 6.6 actual EFPY away. from Oconee 3 but 3.1 EFPY away after normalizing on head temperatures down to 600 degrees.
r Model is purposely simplistic in that PWSCC is influenced by Environment (Chemistry & Temperature),
Stress, and Time. The model does not account for Stress, Chemistry, or specific plant as-built conditions.
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Conducted and recorded video inspections of the head during 11 RFO (April 1998) and 12 RFO (April 2000) n Re-reviewed video inspections of head in light of boron leakage seen at Oconee and Arkansas Nuclear.
No head penetration leakage was identified.
SCommitted to submit follow-up response on January 29, 2002 based upon further industry developments.
Committed to perform a qualified visual of Reactor Pressure Vessel head in 13RFO currently scheduled for April 2002.
Al FENOC
r All CRDM penetrations were verified to be free from "popcorn" type boron deposits using video recordings from I IRFO or 12RFO.
- All through wall cracks in the industry have been identified by visual inspection.
- Plant specific finite element analysis shows that 65 out of 69 will open up sufficiently to provide visual indication.
Remaining 4 CRDMs located in lowest stress area where there have been no circumferential cracks found in the industry.
t'r Critical crack size is 273 degrees which is still a safety factor of 3 (aligns with A SME code).
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AsMmfii Initial conservative crack size of 1800 at beginning of Cycle 12 (1998) i¢ Crack propagates in two directions
.... Industry accepted crack growth rates for Alloy
(,_ 600 are applied Does not credit grows which would rate.
prnV 11 decreasing stresses as crack also decrease crack growth FENOC 8
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Iuasuil I uco Results of Analysis:
This conservative analysis shows that a potential crack would not grow to critical crack size before the 13th refueling outage.
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AdfIifiunaISuppo fiing nlfurmation 7 Continuing industry effort to refine crack propagation cV Continuing industry effort to define effects of chemical environment i
Plant specific fracture mechanics evaluation and crack growth analysis by SIA (Structural Integrity Associates).
,* Plant specific leakage analysis for critical crack size by SIA.
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ý NSSS vendor-specific provides estimated core d4 3.4 E-7 risk assessment amage freq uency of Per RG 1.174 this is categorized as a small" increase in risk*
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There is a reasonable basis for assurance that Davis-Besse is safe to operate based on deterministic and probabilistic assessments until next refueling outage.(March 2002) i We want to have,,the opportunity to continue dialog "FENOC 12
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Irlustylfncs Electric Power Research Institute (EPRI) - PWR Materials Reliability Program Interim Alloy 600 Safety Assessments for U.S. PWR Plants (MRP-44), TP-1001491, Part 2, dated May 2001.
EPRI - PWR Materials Reliability Program Response to NRC Review Comments Transmitted by Letter Dated June 22, 2001, to the NEI Relating to MRP-44, dated June 29, 2001 EPRI - PWR Materials Reliability Program Response to NRC Bulletin 2001-01 (MRP-48), 1006284, dated August 2001 FENOC 13 I.'
CIINNJECIR STIMEUINE 1991 - Originally CRDM cracking was identified at Bugey Unit 3 in France June, 1993 -Safety Assessment Written by all three NSSS Owners Group (NUMARC)
October, 1994 - NUREG/CR-6245, "Assessment of Pressurized Water Reactor Control Rod Drive Mechanism Nozzle Cracking' April, 1997 - NRC Generic Letter 97-01 "Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel Closure Head Penetrations", was issued. Industry Responded with Probabilistic Rankings and head inspection plans.
1997 - Electric Power Research Institute (EPRI) - Crack Growth and Microstructural Characterization of Alloy 600 Vessel Head Penetration Materials, TR-109136 (Proprietary)
June 2000 - Electric Power Research Institute (EPRI) - Crack Growth of Alloy 182 Weld Metal in PWR Environments (MRP-21)
December, 2000 - One Leaking Nozzle Oconee 1 February, 2001 - Nine Leaking Nozzles at Oconee 3 March, 2001-One Leaking Nozzle at ANO 1 April, 2001 - Four Leaking Nozzles at Oconee 2 April 2001- - Framatome(ANP - RV Head Nozzle and Weld Safety Assessment, 51-5011603-01 (FTI ANP Proprietary) and 91 -5012567-00 (Non-proprietary)
April 30, 2001 - NRC IN 2001-05, "Throu h-wall Circumferential Cracking of Reactor Pressure Vessel Head Control Rod Drive Mechanism Penetration Nozzles ateUconee Nuclear Station, Unit 3 May, 2001 - Electric Power Research Institute (EPRI) - PWR Materials Reliability Program Interim Alloy 600 Safety Assessments for U.S. PWR Plants (MRP-44), TP-1001491, Part 2 FENOC 14
C WINN owULJCI5IIT TfEILcutL June 29, 2001 - EPRI - PWR Materials Reliability Program Response to NRC Review Comments Transmitted by Letter Dated June 22, 2001, to the NEI Relating to MRP-44 (MRP-50)
August 3, 2001 - NRC Bulletin 2001-01, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles.
August 19, 2001 - EPRI - PWR Materials Reliability Program Response to NRC Bulletin 2001-01 (MRP-48), 1006284 August 24, 2001 - Davis-Besse enters contract with SIA.
September 4, 2001 - Davis-Besse responds to NRC Bulletin 2001-01 September 24, 2001 -NRR transmits via letter Flaw Evaluation Criteria to NEI.
September 28, 2001 - Dr. Brian Sheron telecon with FENOC CNO Robert Saunders urging fall inspection at Davis Besse October 3, 2001 - NRR conference call with Davis-Besse technical personnel to understand NRC Bulletin 2001.-01, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles.
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RV HEAD INSULATION SERVICE STRUCTURE THERMOCOUPLE NOZZLE (ONS-1 AND TMI-1 ONLY)
SUPPORT STEEL 8 OR 9 ACCESS HOLES IN SERVICE STRUCTURE SUPPORT (ONS-1, ONS-2, ONS-3, CR-,3, AND TMI-1 ONLY) 18 ACCESS OPENINGS "MOUSE-HOLES" ALL B&WOG PLANTS CRDM NOZZLES 2" MIN GAP BETWEEN INSULATION AND TOP OF RV HEAD I
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