ML16131A798
| ML16131A798 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 05/06/2016 |
| From: | Cj Fong NRC/NRR/DRA |
| To: | Markley M Plant Licensing Branch II |
| Pfefferkorn C, NRR/DORL 415-8395 | |
| References | |
| CAC MD4727, CAC MF4728 | |
| Download: ML16131A798 (6) | |
Text
May 6, 2016 MEMORANDUM TO:
Michael T. Markley, Branch Chief Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM:
Christopher J. Fong, Team Leader /RA CPfefferkorn for/
Risk Informed Licensing Initiatives Team PRA Licensing Branch Division of Risk Assessment Office of Nuclear Reactor Regulation
SUBJECT:
AUDIT PLAN - PROPOSED RISK-INFORMED APPROACH TO RESOLVE GENERIC LETTER 2004-02 FOR VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 (CAC NOS.
By letter dated May 16, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13137A130) Southern Nuclear Operating Company (SNC) submitted its proposed path to resolve Generic Letter (GL) 2004-02 for Vogtle Electric Generating Plant, Units 1 and 2 (VEGP). Therein, SNC indicated its intention to pursue Option 2b, a full risk-informed resolution path, as described in SECY-12-0093, dated July 9, 2012 (ADAMS Accession No. ML121320270). SNC also indicated its intention to use software developed for use by the South Texas Project Nuclear Operating Company (STP), titled Containment Accident Stochastic Analysis (CASA) Grande, to complete the required risk analysis for VEGP. SNC further committed to submit a license amendment request (LAR) regarding risk-informed GL 2004-02 resolution activities at VEGP, pending the issuance of a U.S. Nuclear Regulatory Commission (NRC) safety evaluation for the analogous STP LAR. In subsequent correspondence (summarized in ADAMS Accession No. ML15327A168), SNC highlighted differences between VEGP and STP with respect to GL 2004-02 issues resolution risk-informed strategies and communicated its intention to use an alternative software platform to support its forthcoming LAR.
The NRC staff has determined that an audit to examine the documentation and software proposed for use by SNC, namely, the Break Accident Debris Generation Evaluator (BADGER) and Nuclear Accident Risk Weighted Analysis (NARWAL), is required to gain a better understanding of the detailed calculations, analyses and/or bases underlying the proposed LAR in support of a risk-informed approach to resolve GL 2004-02 at VEGP.
CONTACT: Candace M. Pfefferkorn, NRR/DRA/APLA/RILIT (301) 415-8395
The enclosure provides the audit plan in accordance with LIC-111, Regulatory Audits, for conveyance to the licensee.
Enclosure:
Audit Plan
ML16131A798 OFFICE NRR/DRA/APLA/RILIT NRR/DSS/SSIB:BC NRR/DRA/APLA/RILIT NAME CPfefferkorn VCusumano CFong DATE 05/06/2016 05/06/2016 05/06/2016
Enclosure AUDIT PLAN PROPOSED RISK-INFORMED APPROACH TO RESOLVE GENERIC LETTER 2004-02 SOUTHERN NUCLEAR OPERATING COMPANY VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 (CAC NOS. MC4727 AND MC4728)
Purpose and Scope By letter dated May 16, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13137A130) Southern Nuclear Operating Company (SNC) submitted its proposed path to resolve Generic Letter (GL) 2004-02 for Vogtle Electric Generating Plant, Units 1 and 2 (VEGP). Therein, SNC indicated its intention to pursue Option 2b, a full risk-informed resolution path, as described in SECY-12-0093, dated July 9, 2012 (ADAMS Accession No. ML121320270). SNC also indicated its intention to use software developed for use by the South Texas Project Nuclear Operating Company (STP), titled Containment Accident Stochastic Analysis (CASA) Grande, to complete the required risk analysis for VEGP. SNC further committed to submit a license amendment request (LAR) regarding risk-informed GL 2004-02 resolution activities at VEGP, pending the issuance of a U.S. Nuclear Regulatory Commission (NRC) safety evaluation for the analogous STP pilot LAR.
In subsequent correspondence (summarized in ADAMS Accession No. ML15327A168), SNC highlighted differences between VEGP and STP with respect to GL 2004-02 issues resolution risk-informed strategies and communicated its intention to use an alternative software platform to support its forthcoming LAR.
The purpose of this audit is to improve NRC staff understanding of the architecture, documentation, validation and verification, and underlying algorithms and equations constituting the software proposed for use by SNC in its forthcoming GL 2004-02 related LAR, namely, the Break Accident Debris Generation Evaluator (BADGER) and Nuclear Accident Risk Weighted Analysis (NARWHAL).
Audit Agenda The audit is scheduled for three days at the ENERCON Office in Albuquerque, New Mexico.
The audit will include an entrance and exit meeting on the first and last day of the audit, respectively.
The agenda will include discussion and/or examination of:
NARWAL quality assurance documentation, including planning, implementation and verification and validation documents.
NARWAL software requirements.
NARWAL architecture and underlying algorithms and equations governing phenomena such as mass balance, pH, chemical effects, debris transport, head loss, degasification, net positive suction head, and boric acid precipitation impacts.
NARWAL graphical user interface features and results output options.
BADGER architecture and features including the computer aided design model, automatic sizing and placement of zones of influence (ZOIs), truncation of ZOIs using control volumes, calculation of insulation and qualified coatings debris quantities, and size distribution methodology.
VEGP-specific example failure calculations including a break-specific case with time dependent results and comparison of results to failure criteria and a bulk simulation case with several thousand breaks defined.
Simplified vs. detailed risk quantification options and an example(s) for both cases.
Loss of Coolant Accident (LOCA) frequency methodology.
Example conditional failure probability and probabilistic risk assessment calculations.
Uncertainty quantification (version 1 vs. version 2 capabilities).
Audit Team The audit team will consist of:
Christopher Fong, Team Leader, Risk Informed Licensing Initiatives Team, NRR Victor Cusumano, Chief, Safety Issue Resolutions Branch, NRR Candace Pfefferkorn, General Engineer, Risk Informed Licensing Initiatives Team, NRR Ashley Smith, Reactor Systems Engineer, NRR Stephen Smith, Sr. Reactor Systems Engineer, NRR The following support personnel are requested:
SNC representatives and/or ENERCON personnel familiar with the NARWAL and BADGER software and VEGP specific applications.
Documents Requested for Staff Examination No documents are requested prior to the audit. During the audit, documents may be requested by the NRC staff to aid in understanding of the NARWAL and BADGER software and its underlying architecture and algorithms/equations.
Logistical Considerations The following logistics are requested:
Telephone available to call NRC Headquarters.
Designated private space for internal NRC staff discussion.
A computer with running version of NARWAL/BADGER software.
Wireless internet in meeting spaces.
To facilitate resolution of logistical considerations, the NRC staff conducted a pre-audit conference call and a webinar with SNC representatives and ENERCON personnel.
Documentation of Audit Following the audit, the NRC staff will prepare an audit summary documenting the information reviewed during the audit, and any open items identified as a result of the audit. The NRC staff will also document its understanding of the proposed resolution of any identified open items.
The audit summary may be provided to the licensee in draft form for proprietary markup.