ML20176A599
| ML20176A599 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 06/29/2020 |
| From: | Richard Guzman NRC/NRR/DORL/LPL1 |
| To: | Dominion Energy Nuclear Connecticut |
| Guzman R | |
| Shared Package | |
| ML20176A601 | List: |
| References | |
| EPID L-2020-LRM-0040 | |
| Download: ML20176A599 (5) | |
Text
June 29, 2020 LICENSEE:
Dominion Energy Nuclear Connecticut, Inc.
FACILITY:
Millstone Power Station, Unit No. 2
SUBJECT:
SUMMARY
OF MAY 26, 2020, PRE-SUBMITTAL TELECONFERENCE WITH DOMINION ENERGY NUCLEAR CONNECTICUT, INC. RE:
PROPOSED ALTERNATIVE REQUEST RELATED TO STEAM GENERATOR RETAINING WELDS AND FULL PENETRATION WELDED NOZZLE EXAMINATIONS (EPID L-2020-LRM-0040)
On May 26, 2020, the U.S. Nuclear Regulatory Commission (NRC) staff held a public teleconference with representatives of Dominion Energy Nuclear Connecticut, Inc (DENC or the licensee). The purpose of the meeting was to discuss the licensees proposed alternative request to extend the examination interval for the steam generator Class 1 and 2 pressure-retaining welds and full penetration welded nozzles from 10 years to 30 years for Millstone Power Station, Unit No. 2 (Millstone 2). On May 14, 2020, the meeting notice and agenda were posted on the NRC public webpage (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20135H019). The licensees presentation is available at ADAMS Accession No. ML20143A077. A list of attendees is enclosed.
The licensee presented a summary of the following:
affected components proposed alternative basis for the request and technical justification applicability and inspection history projected schedule for submission Affected Components The licensee provided a brief overview of its alternative request and the key goals at the start of the meeting. DENC explained that the affected components are applicable to the Millstone 2 steam generator Class 1 and 2 pressure-retaining welds and full penetration welded nozzles.
The affected components are in American Society of Mechanical Engineers (ASME)Section XI, Table IWB-2500-1 and Table IWC-2500-1, Examination Categories B-B, B-D, C-A, and C-B.
Summary of the Proposed Alternative The licensee proposes to increase the inspection interval for the affected components to 30 years from the current 10-year inspection requirement. The proposed alternative would be applicable for the remainder of the fifth, and through the following sixth, 10-year inspection intervals. The duration of the proposed alternative would end on March 31, 2040, which would be pending the subsequent license renewal beyond July 31, 2035, for Millstone 2. The licensees submittal would be based on an alternative that demonstrates an acceptable level of quality and safety in accordance with Title 10 of the Code of Federal Regulations 50.55a(z)(1).
Basis for the Request and Technical Justification DENC is proposing two technical basis documents to support its alternative request. The first report, Electric Power Research Institute (EPRI) Report No. 3002015906, will cover the technical bases for the inspection requirements for the steam generator Class 1 nozzle-to-vessel welds and the Class 1 and 2 vessel head, shell, tubesheet-to-head, and tubesheet-to-shell welds. The second report, EPRI Report No. 3002014590, will cover the technical bases for the nozzle-to-shell welds and nozzle inside radius sections. The licensee stated that both reports are non-proprietary and publicly available. Specifically, the EPRI technical justification reports provide information on (1) examination history for the industry with no reportable service-related flaws; (2) previous industry initiatives to optimize the examinations for similar components such as the reactor vessel welds for justifying extended intervals; and (3) evaluations related to degradation mechanism, probabilistic fracture mechanics (PFM), and deterministic fracture mechanics for the other subject welds and nozzles, concluding that no other inspections are required for 80 years to meet certain NRC safety criteria.
The licensee also stated that the PFM software used to compile the EPRI reports is consistent with a PFM white paper submitted to the NRC by EPRI. DENC indicated there are currently no approved precedents for this type of request; however, it indicated that a similar alternative request was submitted for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2, in December 2019 for the Examination Category C-B components.
Applicability and Inspection History The licensee stated that the proposed alternative request will demonstrate that plant-specific configurations and operating conditions for Millstone 2 are bounded by the criteria of the EPRI technical justification reports. The licensee also reviewed its examination history from initial preservice through subsequent inservice interval inspections and confirmed that Millstone 2 has not had any service-induced flaws exceeding the ASME Section XI acceptance standards. The licensee concluded that the ASME Section XI inspection schedules can be optimized and will continue to provide an acceptable level of quality and safety.
Projected Schedule for Submission The licensee stated its planned submittal is on track and projected for submission by the end of June 2020. DENC intends to request an approval date of August 2021 to support the fall 2021 refueling outage for Millstone 2.
Comments or Questions from NRC Staff The NRC staff asked the licensee whether the same PFM software codes are used for both EPRI technical justification reports. DENC confirmed that both EPRI reports use the same code (referred as the PROMISE Code), which is the code currently under review for the Vogtle, Units 1 and 2, alternative request. The NRC staff also inquired whether there had been any changes to the PFM codes or to the EPRI reports since the time of submittal of the Vogtle, Units 1 and 2, alternative request (December 2019). The licensee stated that there have been no changes to the code or the EPRI reports since they were submitted for NRC staff review.
The staff asked whether the licensee plans to send the EPRI reports as separate enclosures to the alternative request submittal. The licensee stated that it intends to reference the EPRI reports in its submittal and confirmed that both reports are non-proprietary, publicly available reports.
The staff also requested clarification on the presentation slide listing all affected components and whether there were any nozzle-to-pipe welds subject to the proposed alternative request.
The licensee confirmed that the proposed alternative does not include any nozzle-to-pipe welds.
Lastly, the staff stated that while it is conducting an audit on the PROMISE Code as part of the Vogtle, Units 1 and 2 review, it is not examining the items applicable to ASME Categories B-B, B-D, and C-A. The NRC staff commented that auditing those items may be considered as part of the Millstone 2 specific request (i.e., there are six other welds listed on presendation slide 3 that may be audited separately as part of the staffs review).
No decisions were made regarding the acceptability of the licensees proposed submittal. Four members of the public were in attendance (one representative from the State of Connecticut Department of Energy and Environmental Protection and three representing the nuclear industry). To date, no public meeting feedback forms have been submitted through the NRC public meeting feedback system.
Please direct any inquiries to me at 301-415-1030 or Richard.Guzman@nrc.gov.
Sincerely,
/RA/
Richard V. Guzman, Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-336
Enclosure:
List of Attendees cc: Listserv
Enclosure LIST OF ATTENDEES MAY 26, 2020 PRE-SUBMITTAL TELECONFERENCE WITH DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
PROPOSED ALTERNATIVE RELIEF REQUEST MILLSTONE POWER STATION, UNIT NO. 2 Name Organization Richard Guzman U.S. Nuclear Regulatory Commission (NRC)
David Rudland NRC Brian Wittick NRC Hipo Gonzalez NRC Matt Mitchell NRC Jerome Bettle NRC David Dijamco NRC Ali Rezai NRC Carol Moyer NRC Justin Fuller NRC Eben Allen NRC David Dobson Dominion Energy Nuclear Connecticut, Inc. (DENC)
Joseph Barile DENC Jeffry Langan DENC Marylou Calderone DENC David Hinspater DENC Kevin Hacker DENC Craig Sly DENC Shayan Sinha DENC Robert Grizzi Electric Power Research Institute (EPRI)
Gary Stevens EPRI Jeffrey Semancik Connecticut Department of Energy and Environmental Protection Sara Scott Xcel Energy Brendan Casey Exelon Nuclear Bryan Greenwood Rhode Island Emergency Management Agency
ML20176A601 (Package)
ML20135H019 (Meeting Notice)
ML20176A599 (Meeting Summary)
ML20143A077 (Meeting Slides)
OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/LA NRR/DORL/LPL1/BC NRR/DORL/LPL1/PM NAME RGuzman LRonewicz JDanna RGuzman DATE 06/24/2020 06/24/2020 06/29/2020 06/29/2020