ML14232A156

Request for Additional Information Regarding License Amendment Request to Revise Containment Peak Pressure

ML14232A156
Person / Time
Site:	LaSalle
Issue date:	09/11/2014
From:	Blake Purnell Plant Licensing Branch III
To:	Pacilio M Exelon Generation Co, Exelon Nuclear
Blake Purnell, NRR/DORL 415-1380
References
TAC MF2690, TAC MF2691
Download: ML14232A156 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 11, 2014 Mr. Michael J. Pacilio Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer (CNO)

Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

LASALLE COUNTY STATION, UNITS 1 AND 2- REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE CONTAINMENT PEAK PRESSURE (TAC NOS. MF2690 AND MF2691)

Dear Mr. Pacilio:

By application dated September 5, 2013, as supplemented by letter dated June 12, 2014 (Agencywide Document Access and Management System (ADAMS) Accession Nos.

ML13249A231 and ML14163A690, respectively), Exelon Generation Company, LLC submitted a license amendment request for LaSalle County Station, Units 1 and 2, to revise the peak calculated primary containment internal pressure. The NRC staff is reviewing the submittals and has determined that additional information is needed to complete its review.

A response to the enclosed request for additional information should be provided by October 8, 2014. This request was discussed with Ms. Lisa Simpson and Mr. David Gullatt, of your staff, on September 4, 2014. Should you have any questions, please contact me at 301-415-1380 or by email at blake.purnell@nrc.gov.

Sincerely, Blake Purnell, Project Manager Plant Licensing 111-2 and Planning and Analysis Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-37 4

Enclosure:

Request for Additional Information cc w/encl: Listserv

REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO REVISE PEAK CALCULATED PRIMARY CONTAINMENT PRESSURE LASALLE COUNTY STATION, UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-37 4 By application dated September 5, 2013 (Agencywide Document Access and Management System (ADAMS) Accession No. ML13249A231), Exelon Generation Company, LLC (the licensee) submitted a license amendment request for LaSalle County Station (LSCS), Units 1 and 2, to revise the peak calculated primary containment internal pressure (Pa). The U.S.

Nuclear Regulatory Commission (NRC) issued a request for additional information (RAI) on April10, 2014 (ADAMS Accession No. ML14056A443), to which the licensee responded by letter dated June 12, 2014 (ADAMS Accession No. ML14163A690). The NRC staff is reviewing the application and supplemental information and identified the need for additional information to complete its review.

RAI-1

Background The current containment design-basis accident (DBA) analysis for LSCS is described in Section 6.2.1.1.3 of the updated final safety analysis report. Initial conditions for this analysis include the maximum drywell and suppression chamber pressure and the maximum drywell air temperature. These initial conditions are included in Technical Specification (TS) 3.6.1.4, "Drywell and Suppression Chamber Pressure," and TS 3.6.1.5, "Drywell Air Temperature,"

respectively, as they satisfy Criterion 2 of Title 10 of the Code of Federal Regulations (1 0 CFR),

Section 50.36(c)(2)(ii). The Bases forTS 3.6.1.4 states that "the initial pressure limitation requirements ensure that peak primary containment pressure for a DBA LOCA [loss-of-coolant accident] does not exceed the design value of 45 psig."

The application indicates that the Pais higher when using a lower drywell temperature than the maximum drywell temperature allowed by TS 3.6.1.5. The application states that the revised Pa was determined using an initial drywell temperature of 98 degrees Fahrenheit CF). In RAI-5, the NRC staff noted that the TSs contain a maximum drywell air temperature but do not contain a minimum drywell air temperature. In response to RAI-5, the licensee stated that a TS minimum drywell air temperature is not required based on the following data summary:

• The bulk average Drywell temperature is maintained > 100 oF when the reactor power is;;:: 90% CLTP [current licensed thermal power]. The containment analysis used a lower initial Drywell temperature (i.e., 98 oF) to provide conservatism.

• A review of historical data indicates that the bulk average Drywell temperature is less than 100 oF at low power levels (i.e., < 40% CLTP).

Enclosure

Without a minimum drywell temperature limit, the TSs do not reflect the complete range of initial conditions used for the containment DBA analysis. The summary of historical data is insufficient to demonstrate that the revised Pa will bound the full range of operations permitted by the TSs.

Thus, the licensee has not adequately demonstrated that the current TSs will ensure that the peak primary containment pressure for a DBA LOCA does not exceed the design value.

Request Demonstrate that the proposed Pa will not be exceeded for the full range of operations permitted by TSs for Modes 1, 2, and 3. Provide a detailed analysis of any historical information used to support this claim. The response should:

a. Explain how operations with a drywell air temperature less than 98 oF are not possible within specific modes or range of power levels.

b. Explain how operations at a drywell air temperature less than 98 °F, outside those specific modes or range of power levels, will result in a lower Pa Alternatively, provide a proposed TS changes to add a minimum drywell air temperature requirement, consistent with the analysis described in the application, along with a summary statement of the bases or reasons for such specification.

RAI-2

Background In RAI-4.B of the April10, 2014, letter, the NRC staff requested that the licensee provide the latest combined Types Band C test summations at the new Pa. In its response, the licensee provided the as-left minimum pathway leakage results for refueling outages L 1R14 and L2R14, but not the as-found results.

Request Provide the as-found leakage minimum pathway results for refueling outages L 1R14 and L2R14.

ML14232A156 *via e-mail OFFICE LPL3-2/PM LPL3-2/LA SCVB/BC* STSB/BC* LPL3-2/BC LPL3-2/PM NAME BPurnell SRohrer RDennig REIIiott* TTate BPurnell DATE 9/11/14 8/20 /14 8/19/14 ~/25/14 9 /5/14 9/11/14