ML15112A374

Request for Additional Information Regarding the As-Found Lift Tolerances for the Pressurizer Safety Valves License Amendment Request (Tac Nos. MF3541 and MF3542)

ML15112A374
Person / Time
Site:	Calvert Cliffs
Issue date:	05/06/2015
From:	Alexander Chereskin Plant Licensing Branch 1
To:	George Gellrich Exelon Generation Co
Chereskin A
References
TAC MF3541, TAC MF3542
Download: ML15112A374 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 6, 2015 Mr. George H. Gellrich, Vice President Exelon Generation Company, LLC Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702

SUBJECT:

CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 -

REQUEST FOR ADDITIONAL INFORMATION REGARDING THE AS-FOUND LIFT TOLERANCES FOR THE PRESSURIZER SAFETY VALVES LICENSE AMENDMENT REQUEST (TAC NOS. MF3541 AND MF3542)

Dear Mr. Gellrich:

By letter dated February 13, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14050A374), Calvert Cliffs Nuclear Power Plant, LLC, submitted a license amendment request (LAR) that proposed changes to the technical specification surveillance requirements (SRs) for Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2. The proposed LAR would revise the as-found lift tolerances in the SR for the pressurizer safety valves.

The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing the submittal and has determined that additional information is needed to complete its review. The specific questions are found in the enclosed request for additional information (RAI). The NRC staff is requesting a response to the RAls within 45 days of the date of this letter.

If you have any questions regarding this issue, please contact me at (301) 415-1016.

Sincerely,

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Alexancier N. Chereskin, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosure:

Request for Additional Information cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE PRESSURIZER SAFETY VALVE TECHNICAL SPECIFICATIONS CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 CALVERT CLIFFS NUCLEAR POWER PLANT, LLC EXELON GENERATION COMPANY, LLC DOCKET NOS. 50-317 AND 50-318 By letter dated February 13, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14050A374), Calvert Cliffs Nuclear Power Plant, LLC (the licensee), submitted a license amendment request (LAR) that proposed changes to the technical specification (TS) surveillance requirements (SRs) for the Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 (Calvert Cliffs). The proposed LAR would revise the as-found lift tolerances in the SRs for the pressurizer safety valves. Based on its review, the U.S. Nuclear Regulatory Commission (NRC) staff requests the following additional information to complete its safety evaluation of the application:

REACTOR SYSTEMS BRANCH (SRXB) REQUEST FOR ADDITIONAL INFORMATION (RAl)-1:

On page 29 of AREVA analysis of the feedwater line break, calculation 32-9187689-001, estimates are provided for geometric parameters. Please explain the basis for these estimates.

SRBX RAl-2:

A main steam safety valve closure time of 6 seconds is used in the analyses for the pressurization events. The Analysis Of Record (AOR) used a 7 second closure time. Please explain the basis for this change and the effect that it has on the peak pressure.

SRBX RAl-3:

By letter dated February 13, 2014 (ADAMS Accession No. ML14050A374), the licensee submitted a LAR for Calvert Cliffs. The licensee requested approval of the methodology used for the analyses supporting this license amendment. A restriction provided in Appendix C of each unit's operating license requires prior NRC approval of a Calvert Cliffs-specific basis for the use of the methodology documented in AREVA Topical Report EMF-2310 to analyze transient performance relative to reactor coolant pressure boundary integrity.

Enclosure

The licensee provided Attachment 3 to the February 13, 2014, letter that summarizes results of application of the methodology described in AREVA Topical Report EMF-2310 for Calvert Cliffs pressure boundary integrity analysis. For the Calvert Cliffs application, please describe how the initial conditions prescribed by the approved methodology appropriately consider uncertainties, TS Limiting Safety System Settings, or TS Limiting Conditions for Operation. Also, please describe the Calvert Cliffs specific implementation of guidelines in EMF-2310 for analysis assumptions, biasing of parameters, and dispositioning of events.

SRBX RAl-4:

In the LAR, the licensee requested a change to TS 3.4.10 (Pressurizer Safety Valves) to "reduce an unnecessarily restrictive SR." During the audit meeting on March 25, 2015, the licensee's representatives described the as-found setpoints as a very tight tolerance band, tighter than that of most other plants. In addition, the licensee's representatives described how the upper and lower limits of the as-found setpoints are a careful balance between upper limits that will not exceed the American Society of Mechanical Engineers (ASME) Code limit of 110 percent design pressure, and the lower limits that establish operational margin. However, the peak calculated system pressure for the limiting design basis transient (feedwater line break) is 20 psi below the ASME Code limit, after the nominal setpoint for valve RC 201 was reduced 40 psi, which seems to be a large margin compared to a change in the tolerance band of about 25 psi or less. Describe in more detail how the values for the tolerance band were selected so that the SR would not be unnecessarily restrictive.

SRBX RAl-5:

Please explain the changes in the current analysis for the feed line break that resulted in the decrease of the limiting feedline break size from 0.3 square feet in the current analysis to 0.02 square feet in the AOR.

May 6, 2015 Mr. George H. Gellrich, Vice President Exelon Generation Company, LLC Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702

SUBJECT:

CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 -

REQUEST FOR ADDITIONAL INFORMATION REGARDING THE AS-FOUND LIFT TOLERANCES FOR THE PRESSURIZER SAFETY VALVES LICENSE AMENDMENT REQUEST

Dear Mr. Gellrich:

By letter dated February 13, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14050A374), Calvert Cliffs Nuclear Power Plant, LLC, submitted a license amendment request (LAR) that proposed changes to the technical specification surveillance requirements (SRs) for Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2. The proposed LAR would revise the as-found lift tolerances in the SR for the pressurizer safety valves.

The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing the submittal and has determined that additional information is needed to complete its review. The specific questions are found in the enclosed request for additional information (RAI). The NRC staff is requesting a response to the RAls within 45 days of the date of this letter.

If you have any questions regarding this issue, please contact me at (301) 415-1016.

Sincerely, IRA/

Alexander N. Chereskin, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosure:

Request for Additional Information cc w/encl: Distribution via Listserv DISTRIBUTION:

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