ML20207L977
| ML20207L977 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 03/08/1999 |
| From: | Sorensen J NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9903180338 | |
| Download: ML20207L977 (4) | |
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Northern States Power Company Prairie Island Nuclear Generating Plant 1717 Wakonade Dr. East Welch, Minnesota 55089 March 8,1999 10 CFR Part 50 Section 50.46 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 l
PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Report of Corrections to ECCS Evaluction Models By letter dated September 8,1998, Northern States Power Company (NSP) submitted a 30-day report in accordance with the provisions of 10 CFR 50, Section 50.46. The first page of the attachments had the word 3 " Westinghouse Proprietary Class 2C" at the
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top, but there was no justification (for the r roprietary classification) provided to the
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NRC. Subsequent discussion with Westinghouse resulted in their transmittal to NSP of the same page without a proprietary statement; they said that it had been inadvertently J marked proprietary in the first place. This revised page is attached to this letter. We
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regret any inconvenience this may have caused.
In this letter, we have made no new Nuclear Regulatory Commission commitments.
Please contact Jack Leveille (612-388-1121, Ext. 4142) if you have any questions related to this letter.
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Joel P. Sorensen Site General Manager Prairie Island Nuclear Generating Plant c:(see next page) viOOG3 9903180338 990308
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PDR ADOCK 05000282.'
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USNRC NORTHERN STATES POWER COMPANY April 6,199,8 Page 2 ~'
I c: Regional Administrator - Region Ill, NRC Senior Resident inspector, NRC NRR Project Manager, NRC J E Silberg
Attachment:
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I 50-46 01. DOC i
E ATTACHMENT 10 CFR 50.46 Report of Changes Affecting PCT
4 PLANT-SPECIFIC ASSESSMENT TO REBASELINE LIMITING CASE A plant-specific calculation was performed on the Prairie Island plant to rebaseline the limiting break size calculation. The combined effects of all of the code changes since the analysis of record are contained in this calculation. The effect of code modifications were originally generically determined using a method consistent with the 10 CFR 50.46 requirements. The effect of the plant-specific calculation is included on the Margin Utilization Sheets for Prairie Island Units 1 and 2. This is an assessment made to comply with NSP's request, and could change pending Westinghouse's ongoing investigations.
EFFECT OF St IN BROKEN LOOP The effect of modeling safety injection in the broken loop is discussed in detail in NSAL-93-018. The effect was generically determined to be a 150 F penalty, which was included in the 1993 Annual 10
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CFR 50.46 Notification and Reporting Information. A plant-specific assessment of modeling safety injection in the broken loop was performed on Prairie Island, and the revised effect is reflected on the Margin Utilization Sheets for Prairie Island Units 1 and 2. Note that in order to quantify the effects of SI in the broken loop, the break was also moved to a less conservative location, from the bottom of the cold leg to the cold leg centerline in order to establish ECCS spill to containment, consistent with 1
WCAP-10054, Addendum 2, Revision 1. The SI line actually penetrates the cold leg above the centerline, so the revised break location does remain conservative.
EFFECT OF IMPROVED CONDENSATION MODEL.
The effect of the COSI condensation model is discussed in detail in NSAL-93-018. The effect was generically determined to be a 150 F benefit, which was included in the 1993 Annual 10 CFR 50.46 Notification and Reporting Information.
A plant-specific assessment of modeling the COSI condensation model was performed on Prairie Island, and the revised effect is reflected on the Margin Utilization Sheets for Prairie Island Units 1 and 2.