ML20209J113

Safety Evaluation of Topical Rept NSPNAD-8102,rev 7 Reload Safety Evaluation Methods for Application to PI Units. Rept Acceptable for Referencing in Prairie Island Licensing Actions

ML20209J113
Person / Time
Site:	Prairie Island
Issue date:	07/15/1999
From:	NRC (Affiliation Not Assigned)
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References
NUDOCS 9907210129
Download: ML20209J113 (2)

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k S UNITED STATE 8 NUCLEAR REGULATORY COMMISSION i l' $ WASHINGTON, D.C. 2000H001 4., . . . . . /[

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGUI .% TION RELATING TO TOPICAL REPORT NSPNAD-8102. REVISION 7 RELOAD SAFETY EVALUATION METHODS FOR APPLICATION TO PI UNITS NORTHERN STATES POWER CCMPANY

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t PRAIRIE ISLAND NUCLEAR GENERATING PLANT. UNIT 1 AND 2 ~ t

1.0 INTRODUCTION

-t in a letter of January 29,1999 (Ref.1), supplemented by letter dated June 23,1999 (Ref. 2),

Northern States Power Compar y (NSP) requested approval of Revision 7 to topical report NSPNAD-8102, "Re;oad Safety Evaluation ' Methods for Application to PI Units." The revision

contains a description of the new methods developed by NSP for determining the minimum required shutdown margin for an inadvertent boron dilution event initiated from suberitical  ;

conditions (operating modes 3 through 6). In addition, Revision 7 incorporates corrections to sections of the text that either contained errors or needed enhancement. . , j

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! 2.0 EVALUATION  !

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Appendix G to Revision 7 of NSPNAD-8102 describes the methodology for determining the l l minimum required shutdown margin (SDM) for an inadvertent boron dilution event for various ,

l system configurations and dilution flow rates with the reacter subcritical. Termination of the  !

unplanned dilution relies on operator action to stop the event before a complete loss of  ;

shutdown margin occurs. The length of time the operators have to recognize the event and  !

terminak ~.he dilution is dependent r the mass of the reactor coolant system (RCS) being l diluted, ' e dilution flow rate, and the initial shutdown margin.

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Two approaches are described in Appendix G that may be utilized to determine the required SDM for a given system configuration and injection flow rate. Both of these approaches are ussa to show that a complete loss of SDM will not occur for at least 24 minutes from initiation of the inadvertent dilution. This acceptance criterion is applicable for operating modes 3 through 6 and is consistent with the Prairie Island licensing basis. ,

Based on our review, we find the new methods for determining the minimum required SDM for an inadvertent boron dilution event when the reactor is subcritical (Modes 3 through 6) as presented in Appendix G to NSPNAD-8102, Revision 7, are acceptable. Boron dilution events with the reactor critical (operat;ng modes 1 and 2) will continue to be analyzed using the Enclosure 9907210129 990713 PDR ADOCK 05000282 P PDR

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a g methodology described in Section 3 of the topical report. In addition, the corrections to sections of the text in the previous approved version, Revision 6, that either contained errors or needed enhancement, are editorialin nature and are acceptable.

3.0 CONCLUSION

We have reviewed the proposed changes to topical report NSPNAD-8102 submitted in Revision 7 and find them acceptable. Therefore, NSPNAD-8102, Revision 7, is acceptable for referencin l in Prairie Island licenring actions.

4.0 REFERENCES

1. R.O. Anderson (NSP), letter to U.S. Nuclear Regulatory Commission, NSPNAD-8102, Revision 7: Prairie Island Nuclear Power Plant Reload Safety Evaluation Methods for  !

Application to PI Units, January 29,1999.

2. R.O. Anderson (NSP), letter to U.S. Nuclear Regulatory Commission, NSPNAD-8102, Revi sion 7: Prairic Island Nuclear Power Plant Reload Safety Evaluation Methods for Application to P1 Units, June 23,1999.

Principal Contributor. L. Kopp Date: July 15, 1999 .

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