ML20231A743

Request for Additional Information (IOLB/HFT-RAI-1) Dresden MSIV LAR

ML20231A743
Person / Time
Site:	Dresden
Issue date:	08/18/2020
From:	Haskell R Plant Licensing Branch III
To:	Steinman R Exelon Generation Co
Haskell R
References
EPID L-2019-LLA-0232
Download: ML20231A743 (2)

Text

From: Haskell, Russell To: Steinman, Rebecca L:(Exelon Nuclear)

Cc: "Mitchel.Mathews@exeloncorp.com" Bcc: Haskell, Russell

Subject:

Request for Additional Information (IOLB/HFT-RAI-1) re: Dresden MSIV LAR (EPID L-2019-LLA-0232)

Date: Tuesday, August 18, 2020 8:39:00 AM Importance: High

Dear Ms. Steinman,

By application dated October 21, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19294A304), Exelon Generation Company, LLC (Exelon) requested changes to the technical specifications (TSs) for Dresden Nuclear Power Station, Units 2 and 3, to: (1) increase the individual main steam isolation valve (MSIV) leakage rate TS limit of < 34 standard cubic feet per hour (scfh) to < 62.4 scfh for Unit 2 and limit of < 34 scfh to 78 scfh for Unit 3; (2) revise the combined MSIV TS leakage rate of the four main steam lines from the TS limit of < 86 scfh to < 156 scfh for Unit 2 and from < 86 scfh to 218 scfh for Unit 3; (3) eliminate MSIV leakage to no longer be counted in the maximum allowable leakage rate for containment, requiring an exemption from the requirements of 10 CFR 50, Appendix J, Option B; (4) add a new TS 3.6.2.6, Drywall Spray requirement and credit the residual heat removal drywell spray system for fission product removal, and; (5) revise TS 3.6.4.1, Secondary Containment, to address secondary containment short-duration pressure conditions which is consistent with Technical Specification Task Force Traveler (TSTF) 551, Revision 3, Revise Secondary Containment Surveillance Requirements.

The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing your submittal and has identified an area where additional information is needed to complete its review. Please respond to the request for additional information (RAI), as highlighted below. A draft version of this RAI was provided to you on August 12, 2020. On August 16, 2020, you contacted me to state that no further clarifications were necessary from the Exelon staff.

As such, the NRC staff is requesting Exelons response to this RAI by no later than September 15, 2020, to facilitate the NRC staff review of the safety evaluation.

If you have any questions/comments, please contact me.

Thank you.

Russell S. Haskell II United States Nuclear Regulatory Commission (NRC)

Licensing Project Manager - NRR/DORL/LPL 3 Dresden Nuclear Power Station, Units 2 and 3 Russell.Haskell@NRC.Gov; (301) 415-1129 (forwarded); Office: O-8C01; Mail-Stop O-8B1A Inspection Operator Licensing Branch (IOLB/HFT)

Discussion of Regulatory Bases/Issue re: Human Factors (IOLB/HFT-RAI-1)

Changes to TS can have effects on procedures, operator training, and can significantly influence the way that operators perform manual actions.The code of federal regulations (CFR) 10 CFR 50.36(c)(2)(ii) describes conditions which must be addressed by the facility technical specifications.Criterion 3 addresses structures, systems, and components needed to mitigate design basis accidents and transients. The LAR credits the use of a manual operator action to initiate systems to mitigate a design basis accident (criterion 3 of 10 CFR 50.36(c)(2)(ii)), and therefore, this operator action is subject to NRC review.

The following regulatory guidance was considered:

• NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition, Chapter 18, Human Factors Engineering

• NUREG-1764, Guidance for the Review of Changes to Human Actions, Revision 1 Staff Request IOLB/HFT-RAI-1 Page 15 of Attachment 1 of the LAR indicates that it is assumed that operators can initiate the drywell sprays within ten minutes following an event.The NRC staff would like to confirm that there is evidence supporting this assumption.

Please describe the basis for assuring that operators can reliably take the necessary actions to initiate the drywell spray within the ten minutes allowed in the LAR.If the actions required by the LAR are the same as actions currently considered in the time critical operator action program you may consider providing a summary of historical operator performance data for this action.