ML20217D190

Forwards Analyses for Resolution of Seismic Stability Evaluation of Plant Intake Canal,In Support of 970129 LAR Re Amend of Cooling Water Sys Emergency Intake Design Bases

ML20217D190
Person / Time
Site:	Prairie Island
Issue date:	03/23/1998
From:	Sorensen J NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20217D196	List: ML20217D190 ML20217D200 ML20217D204 ML20217D245
References
NUDOCS 9803270351
Download: ML20217D190 (4)

Text

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Northern states Power company 1717 Wakonade Dr. E.

Welch, MN 55089 Telephone 612-388-1121 March 23,1998 10 CFR Part 50 Section 50.90 U S Nuclear Regulatory Commission Attn Document Control Desk Washington, DC 20555

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PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60

Understanding of Required Analyses in Support of License Amendment Request Dated January 29,1997 Amendment of Coolina Water System Emeraency Intake Desian Bases In a meeting on December 11,1997 and subsequent conference calls with the NRC Staff , an understanding was c'eveloped of the analyses required to resolve the intake canal seismic stability issue. On February 18,1998, NSP submitted a letter to the NRC Staff which documt led this understanding and made three commitments to provide three utalyses. This letter transmits the three analyses and' fulfills the three commitments made on February 18,1998.

The following three analyses are provided for resolution of the seismic stability evaluation of Prairie Island's Intake Canal:

1. Attachment 1 provides the analysis which determined the minimum volume of  ;

water needed in the Intake Canal to provide time for operator action to I manage cooling water system loads. The time frame was based upon normal control room staffing, es used in previous validation tests. jbf)}

2. Attachment 2 contains the revised dynamic analysis using Idriss (1990) curves on the canal to assess liquefaction potential. This revised report is in the form of insert pages which fit into the intake Canal Liquefaction Analysis Report provided to the NRC with Supplement 9 dated June 30,1997.

(Insertion instructions are provided.) Based on the results of this revised 9003270351 900323 I PDR ADOCK 0500o282; p PDR '

USNRC

. 3/23/98

- Page 2 of 3 NORTHERN STATES POWER COMPANY report, the slopes and bottom of the intake canal are stable for the postulated design basis earthquake. The computed canal bank slope movement of less than two inches following a design basis earthquake does not pose a threat to blocking the canal or screenhouse structure. Thus, results of this analysis provide the basis for classifying the intake canal as a Design Class 1*

structure, as defined in the Prairie Island USAR, Section 12.2.1. Attachment 3 contains the executive summary, descriptive text and conclusions of the intake Canal Liquefaction Analysis Report (the first 60 pages of the report).

3. As requested by the NRC, Attachment 4 provides a conservative bounding analysis of the canal slope using standard penetration test blow counts based upon the 16th percentile value rather than the median values for each defined soil strata. This analysis also uses the Idriss 1990 damping curve for the dynamic analysis. The intake canal slopes were computed to be stable under design basis earthquake conditions in this bounding analysis.

Attachment 5 contains the report portion of the bounding analysis without any of the attachments (9 pages).

NSP has determined the minimum volume of water that, without use of a dedicated operator in the control room, will provide sufficient time for the operators to manage cooling water system loads following a design basis seismic event. In Attachment 6, this volume of intake canal water is compared to the volume remaining following a design basis seismic event based on the analyses provided in Attachments 2/3 and 4/5. Both comparisons resulted in more than three times the volume of water available compared to the minimum required.

A revised Safety Evaluation, Significant Hazards Determination and Environmental Assessment have not been submitted since these evaluations, as presented in the original January 29,1997 submittal and Supplement 5 dated March 11,1997, continue to bound the proposed license amendment as supplemented by this letter.

If you have any questions related to this supplement to the subject license amendment request, plcase contact myself or Dale Vincent at 612-388-1121.

l 1

Joel P. Sorensen Plant Manager, Prairie Island Nuclear Generating Plant (Attachments and Copies shown on Page 3)

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USNRC e 3/23/98 Page 3 of 3 NORTHERN STATES POWER COMPANY

' Attachments:

. Affidavit

1. NSP Calculation, ENG-ME-347, Minimum Required intake Bay Volume, February 6,1998

2. Revision 1 of the intake Canal Liquefaction Analysis Report for the Prairie Island Nuclear Generating Plant (PINGP), Welch, Minnesota - STS Project No. 28723-A, March 13,1998 (complete Revision 1 including all revised pages)

3. Revision 1 of the intake Canal Liquefaction Analysis Report for the Prairie Island Nuclear Generating Plant (PINGP), Welch, Minnesota - STS Project No. 28723-A, March 13,1998 (first 60 pages of Revision 1 without revised pages for the Appendices)

4. Response to the NSP Request for a Conservative Bounding Analysis for the intake Canal Liquefaction Analysis for the Prairie Island Nuclear Generating Plant, Welch, Minnesota - STS Project No. 28723-A, February 20,1998 (complete report including all attachments)

5. Response to the NSP Request for a Conservative Bounding Analysis for the intake Canal Liquefaction Analysis for the Prairie Island Nuclear Generating Plant, Welch, Minnesota - STS Project No. 28723-A, February 20,1998 I (report without attachments, 9 pages) {

6. NSP Calculation, ENG-ME-355, Intake Canal Available Water Volume Comparison Analysis, March 17,1998 Copies Regional Administrator - lil, NRC (Attachments 1, 3, 5, 6)

NRR Project Manager, NRC [ Attachments 1, 2 (3 copies), 3, 4 (3 copie,s), 5, 6)

Senior Resident inspector, NRC [ Attachments 1,3,5,6)

State of Minnesota (Attachments 1, 3, 5, 6)

Attn: Kris Sanda J E Silberg [ Attachments 1,3, 5,6)

C UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT DOCKET Nos. 50-282 50-306 REQUEST FOR AMENDMENT TO OPERATING LICENSES DPR-42 & DPR-60 LICENSE AMENDMENT REQUEST DATED January 29,1997 Amendment of Coolina Water System Emeroency intake Desian Bases Northern States Power Company, a Minnesota corporation, by this letter dated March 23,1998, with its attachments provides supplemental information in support of the subject license amendment request dated January 29,1997. Attachment 1 provides the determination of the minimum volume of water that must be available in the intake bay. Attachment 2 contains devision 1 update information which revises the analyses presented in the supplement dated June 30,1997. Attachment 3 contains the first 60 pages of the Revision 1 update. Attachment 4 provides a conservative bounding analy* sis of the intake canal using Standard Penetration Test blow counts based on the 16 percentile for each soil strata. Attachment 5 provides the first 9 pages of the conservative bounding analysis without the attachments.

Attachment 6 presents the volume of intake canal water required to allow operators to manage cooling water loads following a design basis seismic event and compares this to the volume remaining based on the analyses provided in Attachments 2/3 and 4/5.

This letter and its attachments contain no restricted or other defense information.

NORTHERN STATES POWER COMPANY By

/Jf41 P. Sorens'en

' Plant Manager Prairie Island Nuclear Generating Plant On thisMch day of [ before me a notary public in arid for said County, persondHy_ appeared, Joel P. Sorensen, Plant Manager, Prairie Island Nuclear Generating Plant, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made in it are true and that it is not interposed for delay.

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