NLS2008005, Implementation of License Amendment No. 227, Increased Spent Fuel Pool Capacity

Implementation of License Amendment No. 227, Increased Spent Fuel Pool Capacity

ML080350010
Person / Time
Site:	Cooper
Issue date:	01/29/2008
From:	Vanderkamp D Nebraska Public Power District (NPPD)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NLS2008005
Download: ML080350010 (4)

Text

N Nebraska Public Power District Always there when you need us NLS2008005 January 29, 2008 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Implementation of LicenseAmendment No. 227, Increased Spent Fuel Pool Capacity Cooper Nuclear Station, Docket No. 50-298, DPR-46

Reference:

Letter from Carl F. Lyon, U.S. Nuclear Regulatory Commission, to Stewart B.

Minahan, Nebraska Public Power District, dated September 6, 2007, "Cooper Nuclear Station - Issuance of Amendment Re: Onsite Spent Fuel Storage Expansion (TAC No. MD3349)"

Dear Sir or Madam:

The purpose of this letter is to inform the Nuclear Regulatory Commission (NRC) staff of actions taken at the Cooper Nuclear Station (CNS) to resolve an issue identified during placement of a storage rack into the spent fuel pool (SFP) following issuance of Amendment No. 227 to the CNS operating license. Amendment 227, forwarded to the Nebraska Public Power District (NPPD) by the reference letter, authorized an increase in the capacity for storage of spent fuel in the SFP at CNS. This discussion of the actions taken to resolve this issue was requested by the NRC Project Manager for CNS.

Following receipt of the amendment a new spent fuel rack was initially placed into the SFP.

At that time two structural elements associated with the existing cask restraint system in the SFP were discovered which created clearance issues near the top of the rack. These elements had not been previously identified. This created the potential for impact between the 'rack and adjacent structures in the event of a Safe Shutdown Earthquake (SSE). This was contrary to the conclusion of the SSE analyses, as stated in the safety evaluation (SE) issued with Amendment 227, that there would be no contact between the rack and adjacent structures.

Various options to restore agreement with the conclusion of the seismic analyses and the Amendment 227 SE that there would be no impact between the rack and adjacent structures were considered. It was ultimately decided that the most prudent course of action was to modify the rack. The rack was removed from the SFP and modified by the removal of the upper portion of four storage cells. Then a portion of the cell wall of each of the four storage locations was bent across the cell opening. This modification eliminated the potential for COOPER NUCLEAR STATION P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 www.nppd.com LL/~1

NLS2008005 Page 2 of 2 impact between the rack and the adjacent structures during a postulated seismic event, as well as precluding placement of fuel assemblies into the four modified cells.

The modification to the storage rack was evaluated and documented in accordance with site procedures. The proposed modification was evaluated in accordance with 10 CFR 50.59.

This evaluation concluded that the rack could be modified without prior NRC review and approval.

Statements from the SE that discuss gaps between the new rack and adjacent structures are identified in Attachment 1. These statements remain true with the modified rack.

Should you have any questions concerning this matter, please contact me at (402) 825-2904.

Sincerely, David Van Der Kamp Licensing Manager

/rr Attachment cc: Regional Administrator w/ attachment USNRC - Region IV Cooper Project Manager w/ attachment USNRC - NRR Project Directorate IV-1 Senior Resident Inspector w/ attachment USNRC - CNS Nebraska Health and Human Service w/ attachment Department of Regulation and Licensure NPG Distribution w/o attachment CNS Records w/ attachment

NLS2008005 Page 1 of 1 Attachment 1 Statements from Amendment 227 Safety Evaluation Cooper Nuclear Station, Docket No. 50-298, DPR-46 No. SE Section no. Statement from SE 1 2.1.2, "Technical The smallest gap between the new racks and the walls of the SFP Evaluation" will be 10 1/16 inches. The smallest gap between the new racks and the nearest structuralmember will be 3 29/32 inches. There will be at least 27 inches between the new racks and the existing racks.

2 2.3.4.1, "Placement The gaps between the new racks and the existing racks and walls of New Racks" of the SFP are large enough to prevent contact and to minimize fluid couplingforces duringa seismic event.

3 2.3.4.1, "Placement Based on the restraintpattern of the existing racks and the of New Racks" spacing between the new racks and the existing racks and walls of the SFP, the NRC staff concurs with NPPD's conclusion that it is acceptable to analyze the new rack modules by the 'single rack seismic analysis'procedure.

4 2.3.4.6, "Acceptance In addition, the new racks are not permitted to impact adjacent Criteria" SFP structures, including the existing racks and structural restraints.

5 2.3.4.8, "Parametric Based on the results of these analyses, NPPD concludes that (1)

Review" the new racks possess a large margin of safety against impact and an even largermargin of safety against overturning, (2)... Section 6.8 of Enclosure 1 of the NPPDsubmittal [i.e., the Holtec Licensing Report] tabulates the maximum calculatedrack displacements and minimum clearances to demonstrate that the new racks do not impact the adjacent SFP walls or the seismic restraints of the existing racks.

ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS@

O.ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© Correspondence Number: NLS2008005 The following table identifies those actions committed to by Nebraska Public Power District (NPPD) in this document. Any other actions discussed in the submittal represent intended or planned actions by NPPD. They are described for information only and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.

COMMITMENT COMMITTED DATE COMMITMENT NUMBER OR OUTAGE None

.1. &

4 4 4 4 4 4 4 4 4 $

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