NLS2021065, Clarification of Response to Nuclear Regulatory Commission'S Request for Additional Information for Alternative Request RS-01

Clarification of Response to Nuclear Regulatory Commission'S Request for Additional Information for Alternative Request RS-01

ML21340A239
Person / Time
Site:	Cooper
Issue date:	12/06/2021
From:	Dent J Nebraska Public Power District (NPPD)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NLS2021065
Download: ML21340A239 (3)

Text

H Nebraska Public Power District "Always there when you need us" 10 CFR 50.55a NLS2021065 December 6, 2021 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

Clarification of Response to Nuclear Regulatory Commission's Request for Additional Information for Alternative Request RS-01 Cooper Nuclear Station, Docket No. 50-298, DPR-46

References:

1. Letter from John Dent, Jr., Nebraska Public Power District to the U.S. Nuclear Regulatory Commission, "Response to Nuclear Regulatory Commission's Request for Additional Information for Alternative Request RS-01," dated October 12, 2021 (Accession No. ML21285A286)

2. Letter from John Dent, Jr., Nebraska Public Power District to the U.S. Nuclear Regulatory Commission, "l O CFR 50.55a Relief Request RS-01, Revision O,"

dated June 16, 2021 (Accession No. ML21167A098)

3. Email from Thomas Wengert, U.S. Nuclear Regulatory Commission, to Linda Dewhirst, Nebraska Public Power District, "Cooper - Final RAI RE:

Alternative Request RS-01 (EPID L-2021-LLR-0044)" dated September 15, 2021, (Accession No. ML21258A263)

Dear Sir or Madam:

The purpose of this letter is for the Nebraska Public Power District (NPPD) to provide a written clarification of the response to the Nuclear Regulatory Commission's (NRC) request for additional information (RAI) (Reference 1).

By letter dated June 16, 2021 (Reference 2), NPPD submitted 10 CFR 50.55a request RS-01, Revision 0, to the NRC. Request RS-01 proposed a grace period for the OMN-13 examination interval of 10 years. By email dated September 15, 2021 (Reference 3) the NRC made a request for additional information which NPPD responded to by letter dated October 12, 2021 (Reference 1). The NRC requested clarification of the response provided in the October 12, 2021 letter during a November 16, 2021 phone call between the NRC project manager and NPPD. Clarification of the response was provided verbally to the NRC during a November 18, 2021 conference call between NPPD, the NRC project manager and NRC technical reviewer. At the completion of the discussion it was requested that the verbal clarification presented be provided in writing and is included as follows:

COOPER NUCLEAR STATION 72676 648A Ave/ P.O. Box 98 / Brownville, NE 68321 http://www.nppd.com

NLS2021065 Page 2 of3 Clarification Request for the NPPD Response to RAl-3:

It is not clear from the relief request or RAJ response how long of a grace period beyond 10 years is requested by Cooper in this relief request.

NPPD Response:

In the original submittal for RS-01, Cooper Nuclear Station (CNS) proposed that for any snubber examination coming due during a snubber refueling outage campaign period (60 days prior to the start of the refueling outage up to plant startup), the examination and evaluation shall be completed prior to plant startup for that refueling outage. This time period would result in a worst case grace period of approximately 90 days beyond the OMN-13 10 year interval.

Therefore, for clarification purposes, CNS proposes that the OMN-13 examination period be 10 years with a grace period not to exceed 90 days for the remainder of the fifth ten-year interval.

Clarification Request for the NPPD Response to RAl-5 and RAl-6:

The Service Life Monitoring ISTD-6100 ofISTD-6000 requires that initial service life ofall snubbers shall be predicted. In addition, ISTD-6200 ofISTD-6000 requires that all snubbers service life shall be evaluated at least once each fuel cycle. [RAl-5J It is not clear from the response how Cooper meets these requirements ofJSTD-6200 for snubbers. [RAl-6} It is not clear how ISTD-6000 is met at Cooper without performing the service life evaluation every fuel cycle (JSTD-6200).

NPPD Response:

In accordance with ISTD-6100, NPPD considered the manufacturer's recommendations and established an initial snubber service life for the mechanical and hydraulic snubbers. Although the recommended design life from Pacific Scientific Company (PSA) was 40 years for the mechanical snubbers, NPPD conservatively elected to implement a service life maintenance activity for mechanical snubbers after approximately 10 years of being installed in the plant.

This was to ensure that the potential service conditions of vibration, heat, and radiation did not adversely impact the performance of the mechanical snubbers. This approach has proven to be very effective as CNS has had an excellent history with the mechanical snubbers. The hydraulic snubber service life is currently at the vendor recommended 25 years and no issues with this service life has been observed.

The ISTD-6200 service life evaluation is a separate requirement from the established service life maintenance activities. At CNS, the ISTD-6200 evaluation is performed at a frequency of once per fuel cycle as required by the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance (OM). The purpose of this review is to ensure that the service life requirements of the ASME OM Code, Subsection ISTD, remain met. Once per cycle, the results from the most recent refueling outage are reviewed, the existing service life durations are reviewed for potential changes, and the upcoming service life expiration dates are reviewed to ensure that no expiration dates will be exceeded prior to the next scheduled refueling outage.

Therefore, CNS meets the requirements of ISTD-6200.

NLS2021065 Page 3 of3 This letter does not contain any new regulatory commitments.

If you have any questions concerning this matter, please contact Linda Dewhirst, Regulatory Affairs and Compliance Manager, at (402) 825-5416.

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Dent, Jr.

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Vice President and Chief Nuclear Officer

/dv cc: Regional Administrator USNRC - Region IV Cooper Project Manager USNRC - NRR Plant Licensing Branch IV Senior Resident Inspector USNRC-CNS NPG Distribution CNS Records