ML023580127

FENOC Meeting Handouts for Meetings with Individual Commissioners Regarding Davis-Besse Nuclear Power Station Reactor Pressure Vessel Head Issues

ML023580127
Person / Time
Site:	Davis Besse
Issue date:	04/07/2002
From:	FirstEnergy Nuclear Operating Co
To:	Office of Nuclear Reactor Regulation
References
Download: ML023580127 (10)

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W 1W S U U U S U S U U U S CRDM Nozzle Issues Tirneline 3R18 NRC Genetic Letter 8S-05 Boric Acid Corrosion of Carbon Steel Reactor Pressure Boundary Components in PW Rs 12/93 M&W safery evalution "External Circum ferential Crack Growth Analysis for B&W Design Reactor Vessel Hlead CRDNI Nozzles.

9/RQ NRC audit of DI boric acid corrosion control program per GL 89-05 I

1/93 B& W issues "Safetv Eialuation for B& W Design Reactor Vesselflead CRDM Nozzle Cracking" T

1989 1990 11/99 DO participation in EPRI M aterials Reliabilty Project 4/97 NRC issues Generic Letter 97-01

• Degradation of CRDM Nozzle and Other Vessel Closure llead Penetrations" 4/96 IORFO visual inspection of head 4/98 II RFO visual inspection of he ad 1991 1992 1993 1994 1995 1996 1997 1998 1999 -

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-1,01 4101 5:01 61(11 7010 8101 2/(tI Oconee 8/01 identifies NRC Bulletin 2001-01 nozzle cracks "Circumferential Cracking of Reactor Pressure Vessel fiead Penetration Nozzles".,,

11/01 A CRS and NRR meetings fuith DB on nozzle cracking 3/I 2/02 DB mobilizesinvestigation team and commits to activities to resolition of head degradation I IAO01

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notifies NRC of first until 13 R FU on Feb 16, 2002 indtion offir irndication of pressure boundary leakage of a penetration nozzle NRC Information Notice 2002-11 on "Recent Experience with Degradation of Reactor Vesselltead" 4/10/02

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Davis-Besse Actions To Date

"* Visual inspections since 1988

"* Commitment to start refueling outage early

"* Compensatory measures until start of refueling outage

"* Most comprehensive inspection of reactor head in industry to date

- Hairline axial cracks found in 5 nozzles

"* Formation of FENOC Investigation Team

" Complete weld repairs on 3 nozzles 11'!

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"* Special team formed to investigate root cause includes Framatome, EPRI, INPO, Oconee, MRP and other industry, experts

"* Team to create, repair plan

"* Safety Assessment submitted to NRC April 8 Plant operated safely during this condition

"* Repair plan to be submitted during April

"* Contingency plan available w New head previously ordered for i

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FENOC Root Cause Summary

"* Probable Cause Through wall cracking of CRDM nozzle, resulting in boric acid corrosion of Reactor Pressure Vessel (RPV) head low-alloy steel.

"* Contributing Causes Failure to clean boric acid from RPV head Design of RPV service structure limited access for cleaning and inspections Deferral of modification to install portals to service structure to allow cleanings and inspections

- Deferral of head cleaning and inspecti,

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FENOC Root Cause Summary (continued)

• Causal Factors Acceptance of boric acid accumulation on RPV head from CRDM flange leakage Failure to recognize symptoms of leakage collected from Containment Building monitors Harsh environmental conditions

-Boric acid corrosion control program targeted CRDM flange leakage