ML20136B229

Safety Evaluation Supporting Amend 46 to License NPF-12

ML20136B229
Person / Time
Site:	Summer
Issue date:	11/07/1985
From:	Office of Nuclear Reactor Regulation
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ML20136B181	List: ML20136B178 ML20136B216 ML20136B229
References
NUDOCS 8511200159
Download: ML20136B229 (2)

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/ '9,, UNITED STATES 8- NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555  !

I SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION , ,

RELATED TO AMENDMENT NO. 46 TO FACILITY OPERATING LICENSE NPF-12 SOUTH CAROLINA ELECTRIC & GAS' COMPANY SOUTH CAROLINA PUBLIC SERVICE AUTHORITY I. INTRODUCTION By letter dated March 6, 1985, South Carolina Electric & Gas Company (the licensee) requested a change to the Virgil C. Sumer Nuclear Station Tech-nical Specification Section 3/4.1.1.2. The proposed change defines the required shutdown margin in terms of Reactor Coolant System (RCS) boron concentration. The change is requested for use beginning with Cycle 3 to ensure that operators have sufficient time to terminate e i inadvertent boron dilution in Modes 3, 4, and 5 following receipt of a high flux at shutdown alarm.

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This amendment request was noticed in the Federal Register (50 FR 16014) on April 23 1985. By letter dated October 18, 1985, the licensee submitted a change to this request which reflected a refinement in the Westinghouse methodology which makes the analysis even better than that accepted by the NRC in its review of the V. C. Sumer Final Safety Analysis Report. This refinement means that the required shutdown margin increases at a slightly faster rate as boron concentration increases, such that the highest required shutdown margin reached is 3.98% versus the 3.29% mentioned in the notice.

This change in shutdown margin is more conservative and does not sub-stantially affect the amendment as noticed; therefore, this amendment, was not renoticed. ,

II. EVALUATION The boron dilution event was analyzed for Cycle 1 and again for Cycle 2.

The licensee plans to begin a transition to an 18-month low leakage fuel management scheme with Cycle 3. Due to the longer fuel cycle the initial boron concentration will be higher. The result is a more rapid loss of shutdown margin because a higher boron concentration can be diluted faster.

Thus, as the initial boron concentration increases, the shutdown margin required to preserve a fixed operator action time also increases.

The analysis showed that for Modes 3, 4, and 5, increases in the shutdown margin are necessary in order to allow the operator sufficient time from l the time of the alarm until margin is lost. The proposed Technical Speciff-cation change based on this analysis properly defines the required shutdown margin as a function of RCS boron concentration for Modes 3, 4, and 5, will maintain the shutdown margin required to provide the necessary operator action time and is acceptable.

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III. ENVIRONMENTAL CONSIDERATION This amendment involves a change in the use of facility components located within the restricted area as defined in 10 CFR Part 20. Thd staff has determined that the amendment involves no significant increase in'the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has pre-viously issued a proposed finding that this amendment involves no signifi-cant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eli categorical exclusion set forth in 10 CFR 51.22(c)(gibility 9). Pursuant criteria for to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

IV. CONCLUSION

, The Commission made a proposed determination that the amendment involves

'no significant hazards consideration which was published in the Federal Register (50 FR 16014) on April 23, 1985, and consulted with the state of South Carolina. No public comments were received, and the state of South Carolina did not have any coments.

The staff has concluded, based on the considerations discussed above, that (1)-there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance wit! the Comission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors: Margaret S. Chatterton, Core Perfonnance Branch, DSI :

Jon B. Hopkins, Licensing Branch No. 4, DL Dated: November 7, 1985 l

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