ML051160253

Memo, Facsimile Transmission of Draft RAI (TAC MC4227 & MC4228)

ML051160253
Person / Time
Site:	Hatch
Issue date:	04/27/2005
From:	Gratton C NRC/NRR/DLPM/LPD2
To:	John Nakoski NRC/NRR/DLPM/LPD2
Gratton C, NRR/DLPM 415-1055
References
TAC MC4227, TAC MC4228
Download: ML051160253 (4)

Text

April 27, 2005 MEMORANDUM TO: John A. Nakoski, Chief, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation FROM: Christopher Gratton, Sr. Project Manager, Section 1 /RA/

Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation

SUBJECT:

HATCH NUCLEAR PLANT, UNITS 1 AND 2 - FACSIMILE TRANSMISSION OF DRAFT REQUEST FOR ADDITIONAL INFORMATION (TAC NOS. MC4227 AND MC4228)

The Nuclear Regulatory Commission (NRC) staff transmitted the attached facsimile containing questions to Mr. Ray Baker of the Southern Nuclear Operating Company on April 1, 2005. The questions supported a conference call with the licensee held on April 14, 2005, regarding the licensees application dated August 23, 2004. The licensees application proposed to replace requirements for valve seat replacement with a requirement to perform Appendix J leakage rate test of the valves at a frequency of at least once every 30 months. This memorandum and the attached questions do not convey or represent an NRC staff position regarding the licensees request.

During the conference call, the NRC staff and the licensee agreed to the following modifications to the draft questions contained in the attachment:

Question 1: Replace the last two paragraphs of the attached draft RAI with the following:

Based upon the review of your submittal, you have stated that increased maintenance frequency is responsible for the testing failure rate. Provide a discussion of the underlying causes that were identified for the testing failures and discuss the corrective actions associated with those failures.

Question 2: Replace the last paragraph of the attached draft RAI with the following:

Considering that Hatchs as-found failure rate exceeded that of other BWRs as evidenced by the operating experience data, provide further justification for your proposal to relax Hatchs testing interval from 24 to 30 months.

Docket Nos. 50-321 and 50-366

Attachment:

Draft Request for Additional Information sent April 1, 2005

April 27, 2005 MEMORANDUM TO: John A. Nakoski, Chief, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation FROM: Christopher Gratton, Sr. Project Manager, Section 1 /RA/

Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation

SUBJECT:

HATCH NUCLEAR PLANT, UNITS 1 AND 2 - FACSIMILE TRANSMISSION OF DRAFT REQUEST FOR ADDITIONAL INFORMATION (TAC NOS. MC4227 AND MC4228)

The Nuclear Regulatory Commission (NRC) staff transmitted the attached facsimile containing questions to Mr. Ray Baker of the Southern Nuclear Operating Company on April 1, 2005. The questions supported a conference call with the licensee held on April 14, 2005, regarding the licensees application dated August 23, 2004. The licensees application proposed to replace requirements for valve seat replacement with a requirement to perform Appendix J leakage rate test of the valves at a frequency of at least once every 30 months. This memorandum and the attached questions do not convey or represent an NRC staff position regarding the licensees request.

During the conference call, the NRC staff and the licensee agreed to the following modifications to the draft questions contained in the attachment:

Question 1: Replace the last two paragraphs of the attached draft RAI with the following:

Based upon the review of your submittal, you have stated that increased maintenance frequency is responsible for the testing failure rate. Provide a discussion of the underlying causes that were identified for the testing failures and discuss the corrective actions associated with those failures.

Question 2: Replace the last paragraph of the attached draft RAI with the following:

Considering that Hatchs as-found failure rate exceeded that of other BWRs as evidenced by the operating experience data, provide further justification for your proposal to relax Hatchs testing interval from 24 to 30 months.

Docket Nos. 50-321 and 50-366

Attachment:

Draft Request for Additional Information sent April 1, 2005 DISTRIBUTION:

PUBLIC RidsOgcRp CHawes (Hard Copy)

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ADAMS Accession Number: ML051160253 NRR-106 OFFICE PM/PDII-1 LA/PDII-1 NAME CGratton CHawes DATE 4/27/2005 4/27/2005 OFFICIAL RECORD COPY

DRAFT REQUESTS FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST APPENDIX J LEAK RATE TEST FOR CONTAINMENT PURGE VALVES SOUTHERN NUCLEAR OPERATING COMPANY HATCH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-321 AND 50-366 In the letter dated August 23, 2004, Southern Nuclear Operating Company (SNC) proposes to amend the Edwin I. Hatch Plant, Units 1 and 2 (Hatch) technical specifications (TSs)

(Surveillace Requirements (SR) 3.6.1.3.11 for Unit 1 and SR 3.6.1.3.12 for Unit 2, and their associated technical specifications bases). The proposal would revise TSs for containment purge valves with resilient seats by eliminating these SRs for replacing the valve seats.

Instead, a Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix J leakage rate test for containment purge valves would be performed every 30 months (i.e., every refueling outage). As a result of the Nuclear Regulatory Commission staffs review, the RAI is as follows:

RAI Question 1 In Enclosure 1 to the August 23, 2004, submittal, you have provided test history of 22 similar design, resilient seat, butterfly valves at Hatch showing that a total of 385 as-found leakage tests have been performed with 68 tests failing to meet the administrative leakage limit (i.e.,

failure rate of 17.7%). You also stated that the total of 68 as-found local leak-rate test (LLRT) failures include 23 seat-related failures and 19 failures with an unknown cause. You have concluded that since Hatch has been replacing the valve seats on a 18 to 48-month interval for most of these valves since the mid-1980s, a review of the Hatch work order records did not identify any failures that were attributable to aging-induced seat degradation.

Additionally, you have also stated that the Hatch data is different from the other boiling water reactor (BWR) experience in that the routine seat replacement interval is much shorter for Hatch than the other plants (18 to 48 months versus 72 to 120+ months), and the failure rate is much greater (17.7% versus 0.6% to 5.4%). Therefore, you state that the increased maintenance frequency associated with seat replacements at Hatch correlates to an increased as-found LLRT failure rate.

Based upon the review of your reasoning, as stated above, you seem to imply that seat replacement causes testing failures. Provide your rationale as to why frequent seat replacement causes a high failure rate. What is the underlying cause for it?

Additionally, having identified the underlying cause for testing failures, describe appropriate corrective actions that could be implemented, other than the proposed TS changes, at Hatch.

Attachment

RAI Question 2 You have concluded in Enclosure 1 to your August 23, 2004, submittal that the technical justification for revising the surveillance frequency of containment purge valves with resilient seats is based on the results from a total of 2457 tests, conducted from 1973 to 2003, that validates the frequency allowed by 10 CFR Part 50 Appendix J, Option B, and Regulatory Guide 1.163, and shows that the additional actions to assure function based on IE Circular 77-11 are not warranted. You have further concluded that this operating experience has shown that for well-maintained butterfly valves with resilient seats, used with a stable environmental and operating conditions, the 30-month leakage rate test interval is sufficiently frequent.

Considering that Hatchs operating experience is significantly worse than that of other BWRs, it seems imprudent to the NRC staff to relax Hatchs testing interval from 24 to 30 months.

Provide further justification for your proposal to relax the testing interval, especially at the same time as eliminating the requirement for seat replacement at a set interval.