ML19204A104
| ML19204A104 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/01/2019 |
| From: | Blake Welling Plant Licensing Branch IV |
| To: | Eichelberger D - No Known Affiliation |
| Klos J | |
| Shared Package | |
| ML19078A287 | List: |
| References | |
| EPID L-2019-CRS-0000, OEDO-19-00131 | |
| Download: ML19204A104 (3) | |
Text
August 1, 2019 Mr. Don Eichelberger 628 Lyon St., #1 San Francisco, California 94117
Dear Mr. Eichelberger:
Your petition dated April 25, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19150A381), was referred to the Office of Nuclear Reactor Regulation pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Section 2.206, Requests for action under this subpart, of the U.S. Nuclear Regulatory Commissions (NRCs) regulations. You requested that Diablo Canyon Nuclear Power Plant, Unit 1 (Diablo Canyon, Unit 1) have independent inspections completed on that Units reactor welds, and that a relief request action dated June 19, 2015 (ADAMS Accession No. ML15168A024), be reversed.
As the basis for your request, you stated that the welds found in Unit 1 contain excessive amounts of copper which are then susceptible to embrittlement. The information related to this request was based on Appendix A of a 2017 report published by Fairwinds Assoc., Inc.,
Neutron Embrittlement at Diablo Canyon Unit 1 Nuclear Reactor, filed as expert testimony of Arnie Gunderson in a case before the California Public Utilities Commission.
Our Petition Review Board (PRB) has reviewed your submittal in accordance with Management Directive 8.11 (MD 8.11), Review Process for 10 CFR 2.206 Petitions (ADAMS Accession No. ML18296A043). The PRBs initial assessment was that your submittal did not meet the criteria for consideration under 10 CFR 2.206, in accordance with MD 8.11,Section III.C, because the issues raised in your petition have already been the subject of the NRC staff review and evaluation.
On July 11, 2019, by e-mail and on July 16, 2019, by telephone, you were informed of the PRBs initial assessment as stated above. During the telephone discussion on July 16,, 2019, the petition manager offered you an opportunity to meet with the PRB to discuss the initial assessment. In response, you informed the petition manager that you chose to not meet with the PRB.
The PRBs final determination is that your request does not meet the criteria for consideration under 10 CFR 2.206 because the issues raised in your petition have already been the subject of the NRC staff review and evaluation as explained below.
The NRC limits each reactor pressure vessel (RPV) allowable pressures and temperatures based on the fracture toughness of the RPV. Specifically, for normal operating conditions the high copper content of the Diablo Canyon, Unit 1, RPV axial weld is taken into consideration when the NRC staff reviews the licensees periodic pressure-temperature (P-T) limit submittals to ensure the requirements of 10 CFR Part 50, Appendix G, Fracture Toughness Requirements, are met. For the postulated severe cooling transients, the Diablo Canyon,
D. Eichelberger Unit 1, high copper axial weld is also periodically reviewed to ensure that the requirements of 10 CFR 50.61, Fracture toughness requirements for protection against pressurized thermal shock [PTS] events, are met. Some of the NRCs previous considerations of these issues can be found in the following documents:
- 1. Safety Evaluation Report, Related to the License Renewal of Diablo Canyon Nuclear Power Plant, Units 1 and 2 (NRCs recent evaluation of P-T limits and PTS for Diablo Canyon, Unit 1), dated June 2011 (ADAMS Accession No. ML11153A103).
- 2. Pacific Gas and Electric Company (PG&E) Letter DCL-14-021 to U.S. Nuclear Regulatory Commission Reactor Coolant System Pressure and Temperature Limits Report for Units 1 and 2 (Diablo Canyon, Unit 1 P-T Limits), dated March 25, 2014 (ADAMS Accession No. ML14084A204).
Regulatory Guide 1.99, Revision 2, Radiation Embrittlement of Reactor Vessel Materials, dated May 1988 (ADAMS Accession No. ML003740284), provides a method to estimate embrittlement of RPV materials due to the copper and nickel contents. The chemistry contents and the estimated time dependent neutron fluence jointly determine a quantitative estimation of embrittlement called nil-ductility-transition reference temperature (RTNDT). For the PTS concern, this RTNDT value is evaluated at the end of operation using the surface neutron fluence and is given a new name, RTPTS. The 10 CFR 50.61 PTS requirements require the RTPTS values for all RPV beltline materials be below the PTS screening criteria to ensure protection against the PTS events. The safety evaluation report for the Diablo Canyon, Unit 1, 60-year license renewal application (listed as Document No. 1 above) concluded that the Diablo Canyon, Unit 1, high copper axial weld will not exceed this PTS criterion until 2032. To date, this estimation remains current.
Thank you for bringing these issues to the attention of the NRC.
Sincerely,
/RA/
Blake D. Welling, Deputy Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-275 cc: Mr. James M. Welsch Senior Vice President, Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 56 Mail Code 104/6 Avila Beach, CA 93424 Listserv
GT Package: ML19078A287; Letter: ML19204A104 *concurrence by email OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL1/LA NRR/DORL/LPL2-2* NRR/DORL/LPL1/BC NAME JKlos PBlechman w/comment PBuckberg RPascarelli DATE 07/23/19 07/25/19 07/25/19 07/30/19 OFFICE NRR/DMLR/MVIB/BC* OGC* NRR/DORL/D PRB Chair NAME DAlley JGillespie CErlanger BWelling DATE 07/25/19 07/29/19 07/31/19 08/01/19