ML20083F589

Request for Additional Information Regarding License Amendment Request Concerning Reactor Coolant Pump Flywheel Inspection Program

ML20083F589
Person / Time
Site:	Calvert Cliffs
Issue date:	03/21/2020
From:	Marshall M Plant Licensing Branch 1
To:	Enrique Villar Exelon Generation Co
Marshall M, NRR/DORL/LPLI, 415-2871
References
EPID L-2018-LLA-0261
Download: ML20083F589 (2)

Text

From: Marshall, Michael To: Villar, Enrique:(GenCo-Nuc) (Enrique.Villar@exeloncorp.com)

Cc: Danna, James

Subject:

CALVERT CLIFFS NUCLEAR POWER PLANT, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST CONCERNING REACTOR COOLANT PUMP FLYWHEEL INSPECTION PROGRAM (EPID L-2018-LLA-0261)

Date: Saturday, March 21, 2020 2:50:38 PM Hello Rick, By letter dated November 21, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19325C128), Exelon Generation Company, LLC (Exelon; licensee) submitted license amendment requests for Calvert Cliffs Nuclear Power Plant, Units 1 and 2 (Calvert Cliffs). The proposed amendments would revise the Reactor Coolant Pump Flywheel Inspection Program. Specifically, the proposed amendments would extend the reactor coolant pump motor flywheel examinations, to an interval not to exceed 20 years. The license amendment request relies on PWROG-17011-NP[-A], Revision 2, "Update for Subsequent License Renewal: WCAP-14535A, 'Topical Report on Reactor Coolant Pump Flywheel Inspection Elimination,' and WCAP-15666-A, 'Extension of Reactor Coolant Pump Motor Flywheel Examination,"' (henceforth the TR) (ADAMS Accession No. ML19318D189) and the associated NRC staff safety evaluation (SE) for the TR (ADAMS Accession No. ML19198A056).

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information provided in the LAR and has determined that additional information is needed to complete its review.Below is the NRC staffs request for additional information.The information being requested is needed to determine inputs to the licensees methodologies assure compliance with Section 50.46(b)(5) of Title 10 of the Code of Federal Regulations.The request for additional information was discussed with you on March 18, 2020, and it was agreed that your response would be provided within 30 days of the date of this email.

REQUEST FOR ADDITIONAL INFORMATION The NRC staffs approval of the TR included four criteria, in the Limitations and Conditions Section of the NRC Staffs SE, that needs to be confirmed by licensees requesting to apply the TR. The fourth criterion states:

[] it is appropriate to use 70 [degrees Fahrenheit] °F as the medium temperature for design limiting event (Table 3-2) in the PFM analysis Exelon stated in the amendment request that the Calvert Cliffs Updated Final Safety Analysis Report (UFSAR) provide the necessary information for confirmation in Section 4.1.3.3.1, Reactor Coolant Pump Flywheel. While other sections of the Calvert Cliffs UFSAR provide some information pertaining to the medium temperature, Revision 51 of the Calvert Cliffs UFSAR did not contain the necessary information to confirm that the medium temperature is 70 °F or higher during operation or event response. This is particularly significant in that a key consideration in the probabilistic fracture mechanics (PFM) approach applied in the UFSAR is the delta between medium temperature and reference temperature for nil ductility transition (RTNDT) of the flywheel materials. While the TR

includes some information concerning the nil-ductility transition temperature, this is insufficient to confirm that even if the normal operation medium temperature is lower than 70 °F (as some other sections of the UFSAR posit) that the PFM would still remain bounding.

Provide a basis to confirm that the medium temperature will be 70 °F or higher consistently, or provide the RTNDT of the flywheel materials such that the medium temperature as described in the UFSAR, when coupled to RTNDT values remain bounded by the TR.

Best Regards, Michael L. Marshall, Jr.

Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation 301-415-2871 Docket Nos. 050-317 and 050-318