RS-21-085, Response to Request for Additional Information Regarding License Amendment Request to Incorporate Licensing Topical Report NEDE-33885PA, Revision 1, GNF CRDA Application Methodology (EPID-L-2021-LLA-0016)
| ML21229A127 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 08/17/2021 |
| From: | Gullott D Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EPID-L-2021-LLA-0016, RS-21-085 | |
| Download: ML21229A127 (5) | |
Text
Exelon Generation 4300 Winfield Road Warrenville, IL 60555 www.exeloncorp.com 10 CFR 50.90 RS-21-085 August17,2021 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
References:
LaSalle County Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374 Response to Request for Additional Information Regarding License Amendment Request to Incorporate Licensing Topical Report NEDE-33885PA, Revision 1, "GNF CRDA Application Methodology" (EPID-L-2021-LLA-0016)
- 1. Letter from D. Murray (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, Application to Incorporate Licensing Topical Report NEDE-33885P-A, Revision 1, "GNF CRDA Application Methodology," dated February 10, 2021 (ML21041A490)
- 2. Letter from B. Vaidya (Project Manager, U.S Nuclear Regulatory Commission) to B. Hanson (Exelon Generation Company, LLC), "LA SALLE UNITS 1 AND 2 -
REQUEST FOR ADDITIONAL INFORMATION (RAI) RE: License Amendment Request to Incorporate Licensing Topical Report NEDE-33885P-A, Revision 1, "GNF CRDA Application Methodology" (EPID-L-2021-LLA-0016), "dated July 26, 2021 In Reference 1, Exelon Generation Company, LLC (EGC) submitted a request to amend Technical Specification (TS) Sections TS 3.1.3, "Control Rod Operability," TS 3.1.6, "Rod Pattern Control," and TS 3.3.2.1, "Control Rod Block Instrumentation," to allow for greater flexibility in rod control operations during various stages of reactor power operation at LaSalle County Station, Units 1 and 2 (LSCS). The proposed amendment will incorporate NRC approved methodology described in Licensing Topical Report, "GNF CRDA Application Methodology," NEDE-33885P-A, Revision 1 (ADAMS Package Accession No. ML20091K212).
In Reference 2, the NRC requested additional information regarding Reference 1. A clarification call between the NRC and EGC was held on July 23, 2021 to ensure a common understanding of the request for additional information.
The Attachment to this letter contains EGC's response to the request for additional information.
August17,2021 Page 2 EGC has reviewed the information supporting a finding of no significant hazards consideration and the environmental consideration provided to the NRC in Reference 1. The supplemental information provided in this letter does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. Furthermore, the supplemental information provided in this letter does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.
There are no regulatory commitments contained in this response.
Should you have any questions regarding this submittal, please contact Jason Taken at 630-806-9804.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 17th day of August 2021.
Gullett, David M.
Digitally signed by Gullatt, David M.
Date: 2021.08.17 10:11 :13
-05'00' David M. Gullatt Director, Licensing and Regulatory Affairs Exelon Generation Company, LLC
Attachment:
Response to Request for Additional Information cc:
NRC Region Ill Regional Administrator NRC Senior Resident Inspector - LaSalle NRC Project Manager, NRR - LaSalle Illinois Emergency Management Agency - Division of Nuclear Safety w/attachments
ATTACHMENT LaSalle County Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374 Response to Request for Additional Information
ATTACHMENT Response to Request for Additional Information RAl-SNSB-1 :
By letter dated February 10, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21041A490}, the Exelon Generation Company, LLC, the licensee for LaSalle County Station, Units 1 and 2 (LSCS), submitted a request to amend the Technical Specifications (TSs), as necessary, to implement new control rod TS requirements associated with the NRC approved methodology described in Licensing Topical Report, "GNF CRDA Application Methodology," NEDE-33885P-A, Revision 1 (ADAMS Package Accession No. ML20091K212).
Regulatory Requirement LSCS were designed to comply with the Nuclear Regulatory Commission (NRC), General Design Criteria (GDC) for Nuclear Power Plant Construction Permits. The regulatory requirements and guidance documents that the NRC staff considered in its review of the proposed amendment included the following:
General Design Criterion 28, "Reactivity limits. " The reactivity control systems shall be designed with appropriate limits on the potential amount and rate of reactivity increase to assure that the effects of postulated reactivity accidents can neither (1) result in damage to the reactor coolant pressure boundary greater than limited local yielding nor (2) sufficiently disturb the core, its support structures or other reactor pressure vessel internals to impair significantly the capability to cool the core. These postulated reactivity accidents shall include consideration of rod ejection (unless prevented by positive means}, rod dropout, steam line rupture, changes in reactor coolant temperature and pressure, and cold water addition.
The Issue of concern In the February 10, 2021, letter, the licensee mentions Appendix B, "Interim Acceptance Criteria and Guidance for the Reactivity Initiated Accidents," to Chapter 4.2, "Fuel System Design," of the Standard Review Plan (NUREG-0800, or SRP), as well as a proposed draft guide, DG-1327, "USNRC Draft Regulatory Guide DG-1327, Pressurized-Water Reactor Control Rod Ejection and Boiling-Water Reactor Control Drop Accidents." Both are referenced in NEDE-33885P-A, Revision 1. Since NEDE-33885P-A was issued, DG-1327 was revised and published as Regulatory Guide 1.236, "Pressurized-Water Reactor Control Rod Ejection and Boiling-Water Reactor Control Drop Accidents," June 2020. While the form of the acceptance criteria for determining fuel rod failures in all three documents are consistent with what the NRC staff considered as part of their review of NEDE-33885P-A, the actual failure thresholds differ somewhat in each document. The licensee does not specify which acceptance criteria it plans it use to determine whether fuel rod failure occurs as part of their use of NEDE-33885P-A.
Request for Additional Information The licensee needs to explicitly clarify which acceptance criteria it plans to use in determining when fuel failure is expected to occur based on the results of the NEDE-33885P-A analyses, and as appropriate, justify the use of the specified acceptance criteria.
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ATTACHMENT Response to Request for Additional Information EGC Response:
EGC plans to use the enthalpy-based acceptance criteria specified in Reference 1 for use in the licensing determinations for control rod drop accidents. These criteria consist of two separate failure mechanisms: Pellet-Clad Mechanical Interaction (PCMI) and High-Temperature Cladding Failure (HTCF). Both are used to show compliance with the acceptance criteria. The PCMI and HTCF acceptance criteria specified in Reference 1 are taken from Reference 2. Reference 1 Sections 3.2 and 3.3 provide the technical detail for each of the failure mechanisms. The Reference 1 methodology has been reviewed and approved.
The PCMI acceptance criteria in References 1 and 2 were refined and finalized in Reference 3.
The PCMI acceptance criteria was changed from a piecewise linear fit of the enthalpy vs.
hydrogen content data in Reference 1 to a curve fit in Reference 3 to be consistent with the other NRC criteria curves. The enthalpy and hydrogen data are unchanged, and the two fitting functions provide similar results.
The HTCF acceptance criteria is identical between References 1 and 3.
Since the differences between the Reference 1 and Reference 3 enthalpy-based acceptance criteria are minor, EGC plans to use the Reference 1 acceptance criteria for determining when fuel (i.e., cladding) failure is expected to occur.
References "GNF CRDA Application Methodology," NEDE-33885P-A Revision 1, March 2020.
2 "Technical and Regulatory Basis for the Reactivity-Initiated Accident Acceptance Criteria and Guidance, Revision 1," March 2015 (ADAMS Accession No. ML14188C423).
3 "Pressurized-Water Reactor Control Rod Ejection and Boiling-Water Reactor Control Rod Drop Accidents," Regulatory Guide RG 1.236, June 2020 (ADAMS Accession No. ML20055F490).
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