ML080450003
| ML080450003 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 02/12/2008 |
| From: | Thadani M NRC/NRR/ADRO/DORL/LPLIV |
| To: | Head S, Walker P South Texas |
| Thadani, M C, NRR/DORL/LP4, 415-1476 | |
| References | |
| TAC MD7495 | |
| Download: ML080450003 (2) | |
Text
From:
Mohan Thadani To:
INTernet:plwalker@stpegs.com; Internet:smhead@stpegs.com Date:
2/12/2008 1:23:22 PM
Subject:
MD7495-STP, Unit 2-One Time Deferral of Code Repair Scott/Phillip:
The NRC staff has reviewed the STPNOC request regarding relief request RR-ENG-2-49 submitted in a letter dated September 6, 2007 for deferral of code repair of a flaw identified in the Unit 2 essential cooling water (ECW) class 3 piping. The NRC staff has identified a need for additional information.
Attached below is a preliminary request for additional information. I request that STPNOCrespond to the subject request within 30 days, to facilitate timely completion of the requested action. If you have any questions, please contact me at (301) 415-1476 or email mct@nrc.gov.
Thanks.
Mohan PRELIMINARY REQUEST FOR ADDITIONAL INFORMATION SOUTH TEXAS PROJECT, UNIT 2 TAC # MD7495 (1) In section 6.2.1 Scope of the subject relief request, the licensee stated that an indication of through-wall dealloying was identified on SBDG #23 cast aluminum-bronze ECW return flow balance throttle valve 2-EW-0204. The licensee also stated that the dealloying indication is a spot with residue buildup on the seat retainer.
Please provide the following additional information:
(a)
Provide a sketch to show how the seat retainer was connected to the valve 2-ES-0204 and the ECW piping.
(b)
Provide a sketch to show the dimensions of the referenced seat retainer (ID, OD, wall thickness and the length of component).
(c)
From the photographs you provided in the e-mail, it appears that the materials of the components adjacent to the seat retainer are different from that of the seat retainer. Identify the adjacent components and its materials.
(d)
Is the referenced valve made of cast aluminum-bronze material? Also discuss the previous service experiences of such valves and associated ECW piping in both units regarding the degradation due to dealloying.
(2) Provide detailed discussion regarding the compensatory action mentioned in 6.1 Proposed Alternative.
(3) Provide details regarding the limiting condition for operation of the affected system as specified in the plant technical specification as discussed in
section 5.0 Impracticality Determination.
(4) Provide detailed discussion to support the statement that this assessment is bounding for the condition under consideration as stated in 6.2.2 Specific Considerations.
(5) Provide detailed discussion regarding the methodology used in flaw evaluation in section 6.2.4, particularly with regard to the methodology described in GL 90-05. Also provide detailed quantitative information regarding the calculated safety margins for the various loading conditions.
(6) Provide detailed discussion to support your findings in section 6.2.6 Conclusion regarding the statement that the referenced degradation that progresses slowly.
CC:
Koo, William Mail Envelope Properties (47B1E41A.EB0 : 23 : 35106)
Subject:
MD7495-STP, Unit 2-One Time Deferral of Code Repair Creation Date 2/12/2008 1:23:22 PM From:
Mohan Thadani Created By:
MCT@nrc.gov Recipients nrc.gov OWGWPO04.HQGWDO01 WHK CC (William Koo)
STPEGS.COM plwalker (INTernet:plwalker@stpegs.com) smhead (Internet:smhead@stpegs.com)
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