ML102040251

RAI Related to the Review of the Diablo Canyon Nuclear Power Plant, Units 1 and 2, License Renewal Application (TAC Nos. ME2896 and ME2897) - Scoping and Screening and Aging Management Review

ML102040251
Person / Time
Site:	Diablo Canyon
Issue date:	08/09/2010
From:	Ferrer N License Renewal Projects Branch 2
To:	Conway J Pacific Gas & Electric Co
Nate Ferrer, DLR/RPB2 415-1045
References
TAC ME2896, TAC ME2897
Download: ML102040251 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 August 9,2010 Mr. John Conway Senior Vice President Generation and Chief Nuclear Officer Pacific Gas and Electric Company 77 Beale Street, MC B32 San Francisco, CA 94105

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE REVIEW OF THE DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION (TAC NOS. ME2896 AND ME2897) - SCOPING AND SCREENING AND AGING MANAGEMENT REVIEW

Dear Mr. Conway:

By letter dated November 23, 2009, Pacific Gas & Electric Company submitted an application pursuant to Title 10 of the Code of Federal Regulations Part 54, to renew the operating licenses for Diablo Canyon Nuclear Power Plant, Units 1 and 2, for review by the U.S. Nuclear Regulatory Commission (NRC or the staff). The staff is reviewing the information contained in the license renewal application and has identified, in the enclosure, areas where additional information is needed to complete the review.

The request for additional information was discussed with Mr. Terry Grebel, and a mutually agreeable date for the response is within 30 days from the date of this letter. If you have any questions, please contact me at 301-415-1045 or bye-mail at nathanieLferrer@nrc.gov.

Sincerely, Nathaniel Ferrer, Project Manager Projects Branch 2 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-275 and 50-323

Enclosure:

As stated cc w/encl: Distribution via Listserv

Diablo Canyon Nuclear Power Plant, Units 1 and 2 License Renewal Application Request for Additional Information Set 18 Scoping and Screening/Aging Management Review RAI 2.3.3.6-02 On LRA drawing LR-DCPP-11-107711-05 at location 59-B, the applicant depicts piping from the isolation valve that leads to the gaseous radwaste vent header as not within the scope of license renewal (i.e., not highlighted), However, on the continuation LRA drawing LR-DCPP-24 106724-03 at location 31-B, the piping is shown as in scope for 10 CFR 54.4(a)(2), The staff requests that the applicant clarify its exclusion of the non-highlighted piping section at the above location on LRA drawing LR-DCPP-11-107711-05, RAI2.3.3.7-02 In license renewal application (LRA) Section 2,3.3.7 the applicant states, 'The safety-related components which are served by the backup air/nitrogen system include valves for charging/spray capability, steam dump capability, RCS boration sample capability, the RCS power-operated relief valves for overpressure protection, the letdown isolation valves, and fire water containment isolation valves~' The applicant continues with, 'The backup air/nitrogen supply system provides compressed gas to safety-related air operated components that are required to perform an active safety-related function after the loss of the compressed air system:'

Letdown isolation valves LCV-459 and LCV-460 are shown in scope of license renewal under 10 CFR 54.4(a)(1) on LRA drawing LR-DCPP-08-106708-03 (at location 32-A). However, the backup nitrogen supply to the valves' air operators is depicted as not in scope of license renewal on LRA drawing LR-DCPP-25-106725-31 (at location 311-C). Since the DCPP LRA description for the compressed gas system specifically includes the letdown isolation valves as one of the safety-related components served by backup gas, then the gas components should be included in the scope of the license renewal under 10 CFR 54.4 (a)(1). The staff requests that the applicant justify excluding the backup air to the letdown isolation valves from scope of license renewal RAI 2.3.3.7-03 The applicant depicts water traps and oil filters in the compress gas system on LRA drawings as not in the scope of license renewal. By the nature of these components, the water traps and oil filters would contain fluid under system pressure. In accordance with the applicanfs methodology as stated in DCPP LRA Section 2.1.2.2, fluid-filled components in the vicinity of SSCs in scope of license renewal under 10 CFR 54.4(a)(1) should be included in the scope of license renewal. The staff requests that the applicant justify the exclusion of these components from the scope of license renewal.

-2 RAI3.1.2.2.14-1 SRP-LR Section 3.1.2.2.14 states that wall thinning due to flow accelerated corrosion (FAG) could occur in steel feedwater inlet rings and supports. GALL Report, item IV.D1-26, references NRC IN 91-19, "Steam Generator Feedwater Distribution Piping Damage," for evidence of wall thinning due to flow accelerated corrosion in these steam generator components and recommends that a plant-specific AMP is to be evaluated because existing programs may not be capable of mitigating or detecting wall thinning due to flow-accelerated corrosion. LRA Section 3.1.2.2.14 addresses wall thinning of steam generator steel feedwater inlet rings and supports due to the aging mechanism of FAC.

The applicant states that since NRC IN 91-19 is specific to Combustion Engineering steam generators and because it does not have this design of steam generator, no action is required.

The applicant also states in plant-specific note 2 of LRA Table 3.1.2-4 that this form of degradation has been detected only in certain Combustion Engineering pre-System 80 steam generators and that its replacement steam generators are Westinghouse Model 54. The applicant further states that no operating experience at DCPP or other units with Westinghouse Model 54 steam generators suggests that wall thinning of the feedwater rings is occurring; therefore it has determined that this condition is not applicable and no further evaluation is required. The staff does not consider IN 91-19 to be limited to Combustion Engineering steam generators; therefore, the applicant should clarify why no action is required for addressing FAC of the feedwater ring. The staff notes that the applicants description of the new steam generator design in the LRA Sections 2.3.1.4 and 82.1.8 does not provide sufficient details about the feedwater inlet ring and supports to judge whether FAC could potentially occur in the new steam generator design.

The applicant states that it will conservatively credit its Water Chemistry Program (82.1.2) and Steam Generator Tubing Integrity Program (82.1.8) to manage wall thinning due to flow accelerated corrosion of the feedwater inlet ring and supports. Moreover, in LRA Table 3.1.2-4, the staff notes that the applicant manages the carbon steel steam generator separators in the same way as the feedwater ring, without providing sufficient explanation. With respect to secondary side steam generator internals, it is not clear to the staff whether all of them are included within the scope of the Steam Generator Tube Integrity Program.

1. Please justify why FAC will not be a concern for these steam generator parts during the period of extended operation.

2. Please confirm that all secondary side steam generator internals, especially the feedwater ring and separators, are included within the scope of your Steam Generator Tube Integrity Program.

' ML102040251 OFFICE LA:DLR PM:RPB2:DLR BC:RPB2:DLR PM:RPB2:DLR NAME YEdmonds NFerrer DWrona NFerrer IDATE 8/2/10 8/4/10 816110 10

Letter to John Conway from Nathaniel Ferrer Last dated August 9,2010.

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE REVIEW OF THE DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION (TAC NOS. ME2896 AND ME2897)-SCOPING AND SCREENING AND AGING MANAGEMENT REVIEW DISTRIBUTION:

HARDCOPY:

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