ML13197A397

Ngp - Sfpc LAR Draft RAI (TAC Nos. ME6984 and ME6985)

ML13197A397
Person / Time
Site:	Prairie Island
Issue date:	06/25/2013
From:	Thomas Wengert Plant Licensing Branch III
To:	George Adams Northern States Power Co
References
ME6984, ME6985
Download: ML13197A397 (4)

Text

1 NRR-PMDAPEm Resource From: Wengert, Thomas Sent: Tuesday, June 25, 2013 11:39 AM To: Adams, Glenn D. (Glenn.

Adams@xenuclear.com)

Cc: Eckholt, Gene F. (Eugene.Eckholt@xenuclear.com)

Subject:

Prairie Island NGP - SFPC LAR Draft RAI (TAC Nos. ME6984 and ME6985)

Attachments:

PINGP Draft RAI Round 04 Rev 0A .pdf Glenn, Please see the attached draft RAI concerning the Prairie Island spent fuel pool criticality license amendment request. Please review and let's arrange for a conference call at your earliest convenience for the NRC staff to clarify this request.

Regards,

Tom Wengert Project Manager USNRC NRR/DORL/LPL3-1

(301) 415-4037 Hearing Identifier: NRR_PMDA Email Number: 762 Mail Envelope Properties (Thomas.Wengert@nrc.gov20130625113900)

Subject:

Prairie Island NGP - SFPC LAR Draft RAI (TAC Nos. ME6984 and ME6985) Sent Date: 6/25/2013 11:39:21 AM Received Date: 6/25/2013 11:39:00 AM From: Wengert, Thomas Created By: Thomas.Wengert@nrc.gov Recipients: "Eckholt, Gene F. (Eugene.Eckholt@xenuclear.com)" <Eugene.Eckholt@xenuclear.com> Tracking Status: None "Adams, Glenn D. (Glenn.Adams@xenuclear.com)" <Glenn.Adams@xenuclear.com> Tracking Status: None Post Office: Files Size Date & Time MESSAGE 365 6/25/2013 11:39:00 AM PINGP Draft RAI Round 04 Rev 0A .pdf 85797 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: Recipients Received:

REQUEST FOR ADDITIONAL INFORMATION NORTHERN STATES POWER COMPANY - MINNESOTA PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-282 AND 50-306 By letter dated August 19, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML11236A133), as supplemented by letters dated May 16, 2012 (ML12139A198), September 4, 2012 (ML12249A069), and February 8, 2013, (ML13039A306) Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (the licensee), requested changes to the Technical Specifications (TSs) for Prairie Island Nuclear Generating Plant, Units 1 and 2 (PINGP). Approval of this license amendment request (LAR) will correct non-conservatisms in the spent fuel pool (SFP) nuclear criticality safety (NCS) analysis of record and the associated Technical Specifications (TSs).

The February 8, 2013, letter contained the following revised commitment:

In conjunction with implementation of the proposed TS, procedures will be revised to require an assessment of a fuel assembly's exposure to rodded power operation in the core prior to moving that fuel assembly into the spent fuel pool (SFP) storage racks. If an assembly experiences more than 100 megawatt days per metric ton uranium (MWd/MTU) of core average full-power rodded operation exposure in the cycle immediately prior to discharge to the spent fuel pool, this exposure experienced while rodded will not be credited for determining the coefficients used to categorize fuel assemblies as described in WCAP-17400-P. In addition if an assembly experiences more than 1 gigawatt day per metric ton uranium (GWd/MTU) of core average rodded operation lifetime exposure, the assembly shall be either treated as Fuel Category 1 or evaluated to determine which Fuel Category is appropriate for safe storage of the assembly.

The second sentence of the commitment would require a fuel assembly that receives between 100 megawatt days per metric ton uranium (MWd/MTU) and 1 gigawatt day per metric ton uranium (GWd/MTU) of rodded operation during a cycle (aka cycle N) to have that portion of its depletion discounted when determining which fuel categories it satisfies for storage. However, that burnup would not have to be discounted for storage determinations following subsequent cycles of operation (i.e., cycles N+1 or N+2). NUREG-6759 indicates that once a positive reactivity effect occurs due to rodded operation, it probably does not ever burnout to zero; therefore any penalty that was incurred would have to follow that fuel assembly for its entire life. Even without that, if the affected fuel assemblies had to be offloaded within a few days of the start of the N+1 cycle, the positive reactivity caused by the rodded operation would not have had time to burnout. Therefore the NRC staff requests that the licensee provide justification for not continuing the rodded operation penalty for the entire life of each affected fuel assembly.

The NRC staff believes that storing any fuel assembly that has more than 1 GWd/MTU of rodded operation as a fresh fuel assembly to be conservative and acceptable. However the phrase or evaluated to determine which Fuel Category is appropriate implies an acceptable methodology for making that evaluation. The NRC staff has been unable to discern the methodology the licensee would use to make this evaluation from the currently submitted information. Therefore, the NRC staff requests the licensee to either provide the rodded operation evaluation methodology for review or strike the phrase from the commitment.