NL-13-0264, Response to Request for Additional Information Concerning the Allowance for Nexus Methodology in the Preparation of the Core Operating Limits Report
| ML13063A291 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 02/28/2013 |
| From: | Pierce C Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-13-0264 | |
| Download: ML13063A291 (9) | |
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Charles R. Pierce Southern Nuclear Regulatory Affairs Director Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992. 7872 Fax 205.992.7601 February 28, 2013 SOUTHERN A.
Docket Nos.: 50-348 COMPANY 50-364 U. S. Nuclear Regulatory Commission NL-13-0264 ATTN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant Response to Request for Additional Information Concerning the Allowance for NEXUS Methodology in the Preparation of the Core Operating Limits Report Ladies and Gentlemen:
By letter dated August 14, 2012, Southern Nuclear Operating Company (SNC),
submitted a license amendment request for the Joseph M. Farley Nuclear Plant (FNP) (ML12227A884). The proposed amendments would revise Technical Specification (TS) 5.6.5, "Core Operating Limits Report (COLR)," to reference and allow use of Westinghouse WCAP-16045-P-A, Addendum 1-A, "Qualification of the NEXUS Nuclear Data Methodology," to determine core operating limits.
The U.S. Nuclear Regulatory Commission staff (NRC) issued a Request for Additional Information (RAI) by letter dated January 30,2013. Enclosure 1 contains the SNC response to RAI questions. Enclosure 2 contains the revised markup of the proposed TS. Enclosure 3 contains the revised clean typed TS.
This letter contains no NRC commitments. If you have any questions, please contact Ken McElroy at (205) 992-7369.
Mr. C. R. Pierce states he is Regulatory Affairs Director of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company, and to the best of his knowledge and belief, the facts set forth in this letter are true.
Respectfully submitted, C1i. ~
C. R. Pierce Regulatory Affairs Director Sworn to and subscribed before me this::(g rh day of J~
,2013.
,~~ ~~ /",
Notary PubliC My commission expires:,/ / - 2: - 2()( :3
U. S. Nuclear Regulatory Commission NL-13-0264 Page 2 CRP/RMJ/lac
Enclosures:
- 1. Response to Request for Additional Information
- 2. Revised Markup of Proposed Technical Specifications
- 3. Revised Clean Typed Technical Specifications cc:
Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. T. A. Lynch, Vice President - Farley Mr. B. L. Ivey, Vice President - Regulatory Affairs Mr. B. J. Adams, Vice President - Fleet Operations RTYPE: CFA04.054 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Ms. E. A. Brown, NRR Project Manager - Farley Mr. P. K. Niebaum, Senior Resident - Farley Mr. J. R. Sowa, Senior Resident - Farley Alabama Department of Public Health Dr. D. E. Williamson, State Health Officer
Joseph M. Farley Nuclear Plant Response to Request for Additional Information Concerning the Allowance for NEXUS Methodology in the Preparation of the Core Operating Limits Report Response to Request for Additional Information to NL 0264 Response to Request for Additional Information NRC RAI #1 U.S. Nuclear Regulatory Commission (NRC) Generic Letter 88-16, "Removal of Cycle-Specific Parameter Limits from Technical Specifications,"
that it is acceptable for licensees to control reactor physics parameter limits by specifying the calculation methodology. The discussion in the GL refers conceptually to the acceptability licensee control of such parameters based on the use of a specific methodology.
Examples include:
"... provided that these changes are determined using an NRC-approved methodology... "
"... using the specified methodology... "
As presently worded, the proposed Technical Specifications amendment would permit Joseph M. Farley Nuclear Plant, Units 1 and 2 (Farley) licensees to choose either of two methods; however, the proposed amendment does not how this would The proposal in effect, a new, more ambiguous, in which either previous method may be applied.
NRC staff is unable determine that this proposal is consistent with 88-16 guidance.
propose a revision to TS that provides for a single, unambiguous method that describes how Limiting Condition for Operation (LCO) 3.9.1 will determined.
SNC Response to RAI #1 The proposed revision to TS 5.6.5 is provided in Enclosure 2 (markup).
The NRC staff evaluation approving WCAP-16045-P-A. Addendum 1 "Qualification the NEXUS Nuclear Methodology,"
that scope of staff was "limited only to the coupling between PARAGON and ANC." This statement implies that one must use PARAGON in order to implement NEXUS. The PARAGON methodology description is substantially more detailed.
and includes descriptions of the numerical techniques are used to solve transport explain how the NEXUS methodology will be applied. given that the proposed TS rO\\J'IClr,n not include reference to the PARAGON methodology. If appropriate, propose a revision to 5.6.5 that refers to methodologies describing both PARAGON NEXUS.
SER for WCAP-16045-P-A, Addendum 1 states:
PARAGON is a alone transport code based on collision probability techniques approved for use as a stand alone lattice physics code and as a cross section generation tool core simulators, as ANC, for uranium-fueled pressurized water reactors (PWRs). ANC is a core simulator code system which performs calculations based on nuclear data supplied by a code such as PARAGON or PHOENIX-P.
Westinghouse to alter coupling between PARAGON and ANC using a different methodology than previously approved by the NRC. The NEXUS methodology
-1 to NL-13-0264 Response to Request for Additional Information is a reparameterization of the PARAGON nuclear data output and a new reconstruction approach within the ANC core simulator code to simplify the use of code for design use. The NEXUS methodology provides a linkage between PARAGON and ANC, establishing a new code while still using PARAGON. Westinghouse refers to this new methodology as NEXUS/ANC.
Given that the NEXUS methodology uses the PARAGON code, SNC maintains that it is not necessary to explicitly reference PARAGON in Section 5.6.5 of the Farley Technical Specifications. Explicitly listing PARAGON code would further complicate Section without providing any additional clarification.
Identify any other core operating limits and safety analyses that will pertormed or determined using inputs from the NEXUS methodology, such as a loss of coolant accident (LOCA) or boron concentration limits. In addition, discuss any potential on post-LOCA long term cooling emergency operating procedure timing boric acid precipitation and action time for switching to simultaneous injection as well as the potential for to power following a large break LOCA during early reflood when highly sub-cooled water its minimum temperature enters the lower portion of the core.
SNC Response to RAI #3 The proposed change does not affect inputs or method(s) for ensuring core subcriticality, both and long-term post-LOCA, thereby precluding the potential for return to power following a large-break LOCA. Since neither the post-LOCA boron source concentration nor generation are impacted by proposed change, current emergency operating procedure timing for boric acid precipitation and the action time for switching to simultaneous injection will continue to remain valid.
design specific parameters that are verified each cycle to conservative with respect to LOCA inputs, such as Fq, FdH, and refueling boron concentration, will continue to calculated using NRC-approved methods.
E1
Joseph M. Farley Nuclear Plant Response to Request for Additional Information Concerning the Allowance for NEXUS Methodology in the Preparation of the Core Operating Limits Report Revised Markup of Proposed Technical Specifications 5.6 Reporting Requirements 5.6 Reporting Requirements 5.6.5 CORE OPERATING LIMITS REPORT (COLR) (continued) 3a.
WCAP-12945-P-A, Volume 1, Revision 2, and Volumes 2 through 5, Revision 1, "Code Qualification Document for Best Estimate LOCA Analysis," March 1998 0!1. Proprietary).
3b.
WCAP-12610-P-A, "Vantage+ Fuel Assembly Reference Core Report," April 1995 (W Proprietary).
(Methodology for LCO 3.2.1 - Heat Flux Hot Channel Factor and LCO 3.4.1-RCS Pressure, Temperature and Flow Departure from Nucleate Boiling Limits.)
3c.
WCAP-16009-P-A, "Realistic Large Break LOCA Evaluation Methodology Using Automated Statistical Treatment of Uncertainty Method (ASTRUM)" M.E. Nissley, et aI., January 2005 (Proprietary).
- 4.
WCAP-8745-P-A, "Design Bases for the Thermal Overpower ~T and Thermal Overtemperature ~T Trip Functions," September 1986 (Westinghouse Proprietary)
(Methodology for Overpower ~T and Thermal Overtemperature ~T Trip Functions)
- 5.
WCAP-14750-P-A Revision 1, "RCS Flow Verification Using Elbow Taps at Westinghouse 3-Loop PWRs. (Westinghouse Proprietary)
(Methodology for minimum RCS flow determination using the elbow tap measurement.)
6a.
WCAP-11596-P-A, "Qualification of the Phoenix-P/ANC Nuclear Design System for Pressurized Water Reactor Cores," June 1988 Commencing Unit 1 Cycle 26 and Unit 2 Cycle 24, method 6b shall be used in lieu of method 6a.
6b.
WCAP-16045-P-A, Addendum 1-A, "Qualification of the NEXUS Nuclear Data Methodology," August 2007.
(Methodology for LCO 3.9.1 - Boron Concentration.)
- 7.
WCAP-11397-P-A "Revised Thermal Design Procedure," April 1989 (Methodology for LCO 2.1.1-Reactor Core Safety Limits, LCO 3.4.1 RCS Pressure, Temperature and Flow Departure from Nucleate Boiling Limits.)
(continued)
Farley Units 1 and 2 5.6-4 Amendment No. 4-74 (Unit 1)
Amendment No. 4-9+ (Unit 2)
Joseph M. Farley Nuclear Plant Response to Request for Additional Information Concerning the Allowance for NEXUS Methodology in the Preparation of the Core Operating Limits Report Revised Clean Typed Technical Specifications 5.6 Reporting Requirements 5.6 Reporting Requirements 5.6.5 CORE OPERATING LIMITS REPORT (COLR) (continued) 3a.
WCAP-12945-P-A, Volume 1, Revision 2, and Volumes 2 through 5, Revision 1, "Code Qualification Document for Best Estimate LOCA Analysis," March 1998 \\t:1.. Proprietary).
3b.
WCAP-12610-P-A, "Vantage+ Fuel Assembly Reference Core Report," April 1995 (W Proprietary).
(Methodology for LCO 3.2.1 - Heat Flux Hot Channel Factor and LCO 3.4.1-RCS Pressure, Temperature and Flow Departure from Nucleate Boiling Limits.)
3c.
WCAP-16009-P-A, "Realistic Large Break LOCA Evaluation Methodology Using Automated Statistical Treatment of Uncertainty Method (ASTRUM)" M.E. Nissley, et aI., January 2005 (Proprietary).
- 4.
WCAP-8745-P-A, "Design Bases for the Thermal Overpower 6T and Thermal Overtemperature 6T Trip Functions," September 1986 (Westinghouse Proprietary)
(Methodology for Overpower 6 T and Thermal Overtemperature 6 T Trip Functions)
- 5.
WCAP-14750-P-A Revision 1, "RCS Flow Verification Using Elbow Taps at Westinghouse 3-Loop PWRs. (Westinghouse Proprietary)
(Methodology for minimum RCS flow determination using the elbow tap measurement.)
6a.
WCAP-11596-P-A, "Qualification of the Phoenix-P/ANC Nuclear Design System for Pressurized Water Reactor Cores," June 1988 Commencing Unit 1 Cycle 26 and Unit 2 Cycle 24, method 6b shall be used in lieu of method 6a.
6b.
WCAP-16045-P-A, Addendum 1-A, "Qualification of the NEXUS Nuclear Data Methodology," August 2007 (Methodology for LCO 3.9.1 - Boron Concentration.)
- 7.
WCAP-11397 -P-A "Revised Thermal Design Procedure," April 1989 (Methodology for LCO 2.1.1-Reactor Core Safety Limits, LCO 3.4.1 RCS Pressure, Temperature and Flow Departure from Nucleate Boiling Limits.)
(continued)
Farley Units 1 and 2 5.6-4 Amendment No.
(Unit 1)
Amendment No.
(Unit 2)