ML16209A413
| ML16209A413 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/27/2016 |
| From: | Eric Oesterle NRC/NRR/DSS/SRXB |
| To: | Markley M Plant Licensing Branch II |
| Forsaty F, NRR/DSS/SRXB 301-415-8523 | |
| References | |
| NSAL-09-5. Rev 1, NSAL-15-I, TAC MF7186, TAC MF7187 | |
| Download: ML16209A413 (6) | |
Text
July 27, 2016 MEMORANDUM TO:
Michael T. Markley, Chief Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Operation FROM:
Eric R. Oesterle, Acting Chief /RA/
Reactor Systems Branch Division of Safety System Office of Nuclear Reactor Regulation
SUBJECT:
SAFETY EVALUATION INPUT FOR NORTH ANNA POWER STATION, UNITS 1 AND 2, PROPOSED LICENSE AMENDMENT TO REVISE THE TECHNICAL SPECIFICATIONS TO ADDRESS THE ISSUE IDENTIFIED IN WESTINGHOUSE DOCUMENTS NSAL-09-5. REV. 1 AND NSAL-15-I (TAC NO. MF7186 AND MF7187)
By letter dated December 10, 2015 (ADAMS Accession No. ML15352A108), Dominion (the licensee) submitted a license amendment request (LAR) for the North Anna Power Station, Units 1 and 2. The proposed license amendment revises the North Anna Power Station Units 1 and 2 technical specifications (TS) to address the issues identified in two Westinghouse Nuclear Safety Advisory Letter, NSAL-09-5, Rev. 1 and NSAL-15-1, Rev. 0 The staff of the reactor systems branch (SRXB) has reviewed the LAR and found that it is acceptable. The SRXB staff provides its bases for approval in the Enclosure.
The safety evaluation input for revision to the North Anna Power Station Units 1 and 2 TS Sections will be provided separately by technical specifications branch and will be included in the final safety evaluation report.
This effort completes the SRXB review of the LAR under TAC No. MF7186 and MF7187.
Docket Nos.: 50-338 50-339 CONTACT: Fred Forsaty, NRR/DSS 301-415-8523
ML15352A108), Dominion (the licensee) submitted a license amendment request (LAR) for the North Anna Power Station, Units 1 and 2. The proposed license amendment revises the North Anna Power Station Units 1 and 2 technical specifications (TS) to address the issues identified in two Westinghouse Nuclear Safety Advisory Letter, NSAL-09-5, Rev. 1 and NSAL-15-1, Rev. 0 The staff of the reactor systems branch (SRXB) has reviewed the LAR and found that it is acceptable. The SRXB staff provides its bases for approval in the Enclosure.
The safety evaluation input for revision to the North Anna Power Station Units 1 and 2 TS Sections will be provided separately by technical specifications branch and will be included in the final safety evaluation report.
This effort completes the SRXB review of the LAR under TAC No. MF7186 and MF7187.
Docket Nos.: 50-338 50-339 CONTACT: Fred Forsaty, NRR/DSS 301-415-8523 DISTRIBUTION:
EOesterle, NRR FForsaty, NRR ADAMS Accession No ML ML16209A413 NRR-106 OFFICE NRR/DSS/SRXB NRR/DSS/SRXB:BC NAME FFORSATY EOESTERLE DATE 07/25/2016 7/ 27 /2016
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO ADOPTION OF DOMINION CORE DESIGN AND SAFETY ANALYSIS METHODS AND TO ADDRESS THE ISSUES IDENTIFIED IN WESTINGHOUSE DOCUMENTS NSAL-09-5, REV. 1, NSAL-15-1 FOR NORTH ANNA POWER STATION UNITS 1 AND 2 DOMINION NUCLEAR CONNECTICUT, INC
1.0 INTRODUCTION
By letter dated December 10, 2015 (ADAMS Accession No. ML15352A108), Dominion (the licensee) submitted a license amendment request (LAR) for the North Anna Power Station (NAPS), Units 1 and 2. The proposed license amendment revises the NAPS Units 1 and 2 technical specifications (TS) to address the issues identified in two Westinghouse nuclear safety advisory letter, NSAL-09-5, Rev. 1 (Reference 1) and NSAL-15-1, Rev. 0 (Reference 2).
In the license amendment request Dominion has proposed the following changes to NAPS TS:
Revise TS 3.2.1, Heat Flux Hot Channel Factor, LCO by removing the former FQ term FQM(Z) and splitting that term into a steady state component FQE(Z) and a transient component FQT(Z);
Revise TS 3.2.1, Actions table to allow a separate Condition/Required Actions/Completion Time structure so each term could be evaluated individually to address NSAL-15-1 thereby allowing continued operation when the LCO is not met; and Revise TS 3.2.1 surveillance requirement (SR) by replacing the single SR with separate SRs that address the steady state and transient components of the FQ term.
2.0 REGULATORY EVALUATION
The U.S. Nuclear Regulatory Commission (NRC) uses the following requirements and guidance documents in evaluating the licensees amendment request:
10 CFR 50.34, Contents of construction permit and operating license applications; technical information, of Part 50 of Title 10 of the Code of Federal Regulations (10 CFR) requires that safety analysis reports analyze the design and performance of structures, systems, and components provided for the prevention of accidents and the mitigation of the consequences of accidents. As part of the core reload process, licensees perform reload safety evaluations to ensure that their safety analyses remain bounding for the design cycle. To confirm that the ENCLOSURE analyses remain bounding, they confirm that the inputs to the safety analyses are conservative with respect to the current design cycle. These inputs are checked using analytical models, and if key safety analysis parameters are not bounded, further analysis of the affected transients or accidents is performed to ensure that the applicable acceptance criteria are satisfied.
10 CFR 50.36, Technical Specifications, paragraphs (d)(2), (d)(3), and (d)(5) state that technical specifications will include limiting conditions for operations, surveillance requirements, and administrative controls. Limiting conditions for operations are the lowest functional capability or performance levels of equipment required for safe operation of the facility.
Surveillance requirements are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met. Administrative controls are the provisions relating to organization and management, procedures, recordkeeping, review and audit, and reporting necessary to assure operation of the facility in a safe manner.
Generic Letter 88-16, Removal of Cycle-Specific Parameter Limits from Technical Specifications, provides guidance for removal of cycle-specific parameter limits from Technical Specifications.
NUREG1431, Rev. 4.0, Standard Technical Specifications for Westinghouse Plants, provides guidance for implementation of Standard Technical Specifications (STS) for Westinghouse plants.
3.0 TECHNICAL EVALUATION
NSAL-09-5, Rev. 1 notified Westinghouse customers of an issue associated with the required actions for condition B of TS 3.2.1B, "Heat Flux Hot Channel Factor FQ(Z) (RAOC-W(Z)
Methodology)," in Reference 3 for plants that have implemented the relaxed axial offset control (RAOC) methodology. In certain situations where transient FQ(Z), is not within its limit, the existing required actions may be insufficient to restore FQ(Z) to within the limit. NSAL-09-5, Rev. 1 provided clarification regarding the applicability of the recommended interim actions to address this issue and how they should be implemented, including potential inclusion in plant specific TS changes. Dominion's evaluation of NSAL-09-5, Rev. 1 determined that it was applicable to NAPS, based on the similarities between the RAOC and Dominion's relaxed power distribution control (RPDC) methodologies.
NSAL-15-1 notified Westinghouse customers of an issue associated with SR 3.2.1.2 in TS 3.2.1B of Reference 3. For certain trends in measured FQ(Z) and non-equilibrium factor W(Z),
the existing SR may not ensure that the transient FQ, FQW(Z), limit will be met between the performance of the monthly flux map measurement, for those plants that use W(Z) FQ surveillance methodology. Dominions evaluation of Reference 2 determined that it was also applicable to NAPS, based on the similarities between RAOC and RPDC methodologies.
The RPDC methodology discussed in Dominion TR VEPNE-1, Rev. 0.1-A, VEPCO Relaxed Power Distribution Control Methodology (Reference 4), and Section 3.2 of the LAR (ADAMS Accession No. ML15352A108) is a Dominion method for axial power distribution control with a variable axial flux difference (delta-I) band. This method provides an increasing delta-I band with decreasing power in order to maintain approximately constant analysis margin to the design bases limits at all power levels.
The RPDC analysis process consists of: (1) the generation of power shapes that bound the delta-I range; (2) the selection of delta-I bands such that all bands satisfy the core operating limits report (COLR) height dependent hot channel factor, FQ(Z), limit with verification that the proposed delta-I bands satisfy loss-of-coolant accident FQ and loss of flow accident thermal-hydraulic evaluations; (3) the analysis of limiting Condition II events to ensure the power shapes within the final delta-I band are used as initial conditions; (4) the verification to confirm that over-power delta temperature (OPT) and over-temperature delta-T (OTT) limits are conservative to ensure that margin to fuel design limits is maintained; and (5) the formulation of N(Z) functions (non-equilibrium power distribution multiplier) to support the implementation of FQ TS surveillance.
The NRC safety evaluation report approving Dominion TR VEP-NE-1, Rev. 0.1-A (Reference 4) accepted the Dominion RPDC method for use at NAPS and SPS, and also allowed the RPDC method for use at plants with reload cores similar to those of NAPS and SPS. Therefore, the use of the RPDC method discussed in Dominion TR, VEP-NE-1, Rev. 0.1-A, and Section 3.2 of the LAR (ADAMS Accession No. ML15352A108) is acceptable to support NAPS licensing applications.
Staffs review indicates that the change in TS 3.2.1, "Heat Flux Hot Channel Factor (FQ(Z)),"
ensures that the required actions will be taken in the event that transient FQ(Z) surveillance limits are not met. Changes are also proposed that define separate terms, action steps and surveillance requirements for steady-state and transient FQ(Z), denoted as FQE(Z) and FQT(Z),
respectively. The use of separate surveillance requirements in this manner is consistent with the NRC approved Westinghouse Standard Technical Specifications, NUREG-1431, Rev. 4 (Reference 3). The revised surveillance requirements provide guidance for application of, and determining the magnitude of a penalty factor for the measured FQ(Z). The factor will be applied if the trend in measured values indicates decreasing margin to the applicable limit since performing the previous surveillance or if the trend in predicted values indicates decreasing margin to the applicable limit prior to the next required surveillance. The proposed changes specify that this factor will be defined in the COLR, which allows specific numerical values of the factor to be evaluated for each reload core. These changes are consistent with the previously NRC approved SR requirements and are acceptable.
In addition, the Bases for TS 3.2.1 are being modified to address the proposed changes to TS 3.2.1. The TS Bases changes are provided for information only. The licensee stated in the LAR that the changes to the TS Bases will be incorporated in accordance with the TS Bases Control Program (TS 5.5.13) and are acceptable.
The proposed TS changes documented in NAPS LAR (ML15352A108) intend to address the issues identified in Westinghouse NSAL-09-5, Rev. 1, and NSAL-15-1 (References 1 and 2).
The specifics of the proposed TS changes are reviewed by the STSB. The results of the STSB evaluation of the proposed TS changes will be added to the SRXB safety evaluation report.
4.0 TECHNICAL EVALUATION
CONCLUSIONS The SRXB staff determined that the proposed changes to TS 3.2.1 are acceptable for NAPS.
This determination is based on the following considerations: (1) that the change in TS 3.2.1, "Heat Flux Hot Channel Factor (FQ(Z))," ensures that the required actions will be taken in the event that transient FQ(Z) surveillance limits are not met and (2) that the use of separate surveillance requirements in proposed manner is consistent with the NRC approved Westinghouse Standard Technical Specifications, NUREG-1431, Rev. 4 (Reference 3) and (3) that the proposed changes are to be evaluated and will be validated for each reload core.
The staff determined based on these considerations that proposed changes are consistent with the requirements of 10 CFR 50.34, 10 CFR 50.36 and GL 88-16.
5.0 CONCLUSION
The NRC has reviewed Dominions submittals and supporting documentation and finds that the proposed use of Dominion nuclear core design and safety analysis methods and the proposed TS changes discussed in the LAR Sections 3.1 and 3.2 are acceptable for use in licensing applications at NAPS.
The NRC staff has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the NRC's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
6.0 REFERENCES
- 1. Westinghouse Nuclear Safety Advisory Letter NSAL-09-5, Rev. 1, dated 9/23/2009, Relaxed Axial Offset Control Technical Specification Actions;
- 2. Westinghouse Nuclear Safety Advisory Letter NSAL-15-1, dated 2/03/2015, Heat Flux Hot Channel Factor Technical Specification Surveillance.
- 3. NUREG-1431, Revision 4, Vol. 1 and 2, "Standard Technical Specifications -
Westinghouse Plants."
- 4. Topical Report, VEP-NE-1, Rev. 0.1-A, "VEPCO Relaxed Power Distribution Control Methodology and Associated FQ Surveillance Technical Specifications," August 2003.
(ADAMS Accession No. ML15313A154)