ML12221A367

Diablo Canyon Power Plant, Units 1 and 2 - Request for Additional Information Email, Request for Alternative No. RI-ISI-INT3 to ASME Code Requirements for Class 1 and 2 Piping Welds, Third 10-Year Inservice Inspection Interval (TAC ME7854 a

ML12221A367
Person / Time
Site:	Diablo Canyon
Issue date:	08/08/2012
From:	Joseph Sebrosky Plant Licensing Branch IV
To:	Soenen P R Pacific Gas & Electric Co
Sebrosky J M
References
TAC ME7854, TAC ME7855
Download: ML12221A367 (2)

Text

From:Sebrosky, JosephTo:Soenen, Philippe RCc:"Baldwin, Thomas (DCPP)"; Hoffman, Keith; Patel, Jigar; Burkhardt, Janet; Chen, Qiao-LynnSubject:Request for Additional Information associated with relief request for risk-informed inservice inspection (ME7854,ME7855)Date:Wednesday, August 08, 2012 2:53:46 PMPhilippe,

By letter dated January 20, 2012, (Agencywide Documents Access and ManagementSystem (ADAMS) Accession No. ML12025A084) Pacific Gas and Electric (PG&E)submitted for staff review and approval Relief Request RI-ISI-INT3-U1&2, which requestsauthorization to continue implementing a risk-informed inservice inspection (RI-ISI)program based on Electric Power Research Institute TR-112657 for American Society ofMechanical Engineers (ASME) Class 1 and 2 piping welds for the third 10-year inspectioninterval at the Diablo Canyon Power Plant Units 1 & 2 (DCPP).

Based on a review of the submittal, the NRC staff has determined that the followingadditional information (RAI) is required in order to complete its review. The request foradditional information was discussed with Mr. Soenen on August 8, 2012. It was agreedthat a response to these RAIs would be provided by September 7, 2012. Should the NRCdetermine that this RAI is no longer necessary prior to the scheduled date, the request willbe withdrawn. If circumstances result in the need to revise the requested response date,please contact me at (301) 415-1132 or via e-mail at joseph.sebrosky@nrc.gov. The NRCstaff has determined that no security-related or proprietary information is contained herein.Sincerely,

Joe Sebrosky REQUEST FOR ADDITIONAL INFORMATION Note: Questions 1 through 6 are from the piping and non-destructive examination branch,and question 7 is from the probabilistic risk assessment licensing branch 1. The NRC issued rulemaking on June 21, 2011 which requires licensees to follow anaugmented inservice inspection program in accordance with ASME Code Case N-770-1, "Alternative Examination Requirements and Acceptance Standards for Class1 PWR Piping and Vessel Nozzle Butt Welds Fabricated With UNS N06082 or UNSW86182 Weld Filler Material With or Without Application of Listed MitigationActivities," and limitations listed in Title 10 of Code of Federal Regulations50.55a(g)(6)(ii)(F). In addition, the NRC held a public meeting to discuss the Junerulemaking and the implementation of Code Case N-770-1 on July 12, 2011. Agencywide Document Access and Management System (ADAMS) accessionnumber # ML112240818 documents the NRC summary of that meeting. The NRCstaff's concern is that, the welds required to be examined in accordance with theaugmented program required by 50.55a(g)(6)(ii)(F) should not be counted asexams selected to satisfy the RI-ISI program. Please describe how DCPP willaddress the requirements of the June 2011 rulemaking and ASME Code Case N-770-1 in implementing Relief Request RI-ISI-INT3-U1&2. 2. Please describe how the proposed RI-ISI program will satisfy the requirements of IWB-2412 and IWC-2412 for percentage of examinations completed. 3. IWB-2420(a) and IWC-2420(a), "Successive Examinations" require that "thesequence of component examinations which was established during the firstinspection interval shall be repeated during each successive inspection interval, tothe extent practical." This requirement is to ensure components are examined on aonce per 10-year frequency to the extent practical. Please discuss how theproposed RI-ISI program satisfies this requirement. 4. The original RI-ISI program required 10% of the ASME Class 1 piping non-socketwelds, is this requirement retained by the 3rd interval RI-ISI program? TheAttachment 1-1 and Attachment 1-2 tables do not identify any ASME Section XIItem Numbers making it impossible for the NRC staff to determine if thisrequirement was retained. 5. The original RI-ISI program stated that RI-ISI examination locations were selectedsuch that >90% coverage is attainable. Was this requirement retained in theexamination locations selected for the proposed program? 6. As a living program the original RI-ISI program required a review of the program onan ASME period basis. Is this requirement retained in the proposed RI-ISIprogram? 7. Risk informed applications must address external events as specified in RegulatoryGuide 1.200 Revision 2. Please provide an assessment for how external events,including seismic events, at Diablo Canyon Power Plant affect the results of the riskimpact analysis for the third ten-year interval inservice inspection program plan.