ML022880301
| ML022880301 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/15/2002 |
| From: | Campbell G, Fyfitch S, Geisen D, Lockwood D, Moffitt S FirstEnergy Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| BL-01-001, FOIA/PA-2002-0345 | |
| Download: ML022880301 (17) | |
Text
NRC Bulletin 2001-01, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles" Presenters:
Guy G. Campbell, Vice President - FENOC Steven P. Moffitt, Director - Technical Services David C. Geisen, Manager - Design Basis Engineering David H. Lockwood; Manager - Regu'latory Affairs Steve Fyfitch, Framatome Engineering FENOC
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- NRC Bulletin 2001-01 response provided Telephone call received on September 28
- Teleconference on October 3
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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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Titled, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles,"
dated August 3, 2001
.r Requests that plants provide information, previous.in'spection inspection plans design results, and future Response requirements were based upon plant rankinq in Susceptibil~fV Model as published in EPRI Mv1RP-48.
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EPRI - PWR Materials Reliability Program Response to NRC Bulletin 2001-01 (MPR-48),
1006284, dated August 2001 SRanked Davis-Besse as 7th out of 69 plants.
i 6.6 actual EFPY away i'.from Oconee 3 but 3.1 EFPY away after normalizing on head temperatures down to 600 degrees.
Model is purposelysimplistic 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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-A f B"C, 0,08ift *SjFORSeO SConducted and recorded video inspections of the head during 11 RFO (April 1998) and 12 RFO (April 2000)
- Re-reviewed video inspections of head in light of boron leakage seen at Oconee and Arkansas Nuclear.
No head penetration leakage was identified.
D Committed to submit follow-up response on January 29, 2002 based upon further industry developments.
SCommitted to perform' a qualified visual of Reactor Pressure Vessel head in 13RFO currently scheduled for April 2002.
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All CRDM penetrations were verified to be free from "popcorn" type boron deposits using video recordings from IIRFO or 12RFO.
, All through wall cracks in the industry have been identified by visual inspection.
- Plant specific finite elemeht analysis shows that 65 out of 69 will open up sufficiently to provide visual indication.
SRemaining 4 CRDMs located inlowest stress area where there have been no circumferential cracks found in the industry.
Critical crack size is 273 degrees which is still a safety factor of 3 (aligns with A SME code).
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r Initial conservative beginning of Cycle 12 crack size of 1800 at (1998)
Crack propagates in two directions
~ Industry accepted-nrack growth rates for Alloy 600 are applied Does not credit grows which would rate.
decreasing stresses as crack also decrease crack growth
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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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Continuing industry effort to refine crack propagation Continuing industry effort to define effects of chemical environme-nt t
Plant specific fracdture mechanics evaluation and crack growth qn~alysis -by SIA (Structural Integrity Associate"s).'
Plant specific leakage analysis for critical crack size by SIA.
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NSSS vendor-specific risk assessment provides estimated core damage frequency of 3.4 E-7 Per RG 1.174 this is categorized as a "very small" increase in risk c0.
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SrThere 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)
A We want to-have,,,te opportunity to continue dialog
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indSiff R loCBS Electric Power Research Institute (EPRI) - PWR Materials Reliability Program Interim Alloy 600 Safety Assessments for U.S. PWR Plants (MRP-44), TP-100 1491, 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 MRPA44, dated June 29, 2001 EPRI - PWR Materials Reliability Program Response to NRC Bulletin 2001-01 (MRP-48), 1006284, dated August 2001 FENOC 13-.......
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'o 11ý -I j 9.11,C11iN81 TiMIIINI 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 "D radation 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 (E1Rl) - Crack Growth of Alloy 182 Weld Metal in PWR Environments (MRP-21)
December, 2000 -One Leaking Nozzle Oconee I 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 51-5012567-00 (Non-proprietary)
April 30, 2001 - NRC IN 2001-05, "Through-wall Circumferential Crackinq of Reactor Pressure Vessel Head Control Rod Drive Mechanism Penetration Nozzles at'Oconee Nuclear Station, Unit 3r 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
91 INON IT'iI I1i/1 I Co o/#
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 F16W 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 PressureVessel Head,Penetration Nozzles.
FENOC T Vt 15
RV HEAD INSULATION SERVICE STRUCTURE CRDM THERMOCOUPLE NOZZLE (ONS-1 ANDTMI-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 2" MIN GAP BETWEEN INSULATION AND TOP OF RV HEAD FENOC 16 I
Circular Cracks - @
Axial Cracks -
Lifting Lug (3 Total)
CRDM Nozzles (69 Total)
Service Structure Support Flange FENOC I
iocatiogs