ML20148C598

Safety Evaluation Supporting Amend 23 to License DPR-54

ML20148C598
Person / Time
Site:	Rancho Seco
Issue date:	10/03/1978
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20148C558	List: ML20148C554 ML20148C568 ML20148C598 ML20148C624
References
NUDOCS 7811020093
Download: ML20148C598 (3)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 23 TO FACILITY OPERATING LICENSE NO. DPR-54 SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING STATION DOCKET NO. 50-312 Introduction By letter dated April .1,1978, we advised the Sacramento Municipal Utility '

District (the licensee) that the definitions of time periods applied to-plant surveillance presently set forth in the Rancho Seco-Nuclear Generating Station Technical Specifications were susceptible to misinterpretation and requested that they propose revised wording to correct this condition. By letter dated June 7,1978, the licensee responded to this request. In addition, the licensee proposed to add a definition for performing surveil-lance on a " Staggered Test Basis."

Background-The definitions of time periods, as applied.to plant surveillance, presently given in the Rancho Seco Technical Specifications are subject to misinter-pretation because the definitions are structured in terms of blocks of time during which surveillance 'may be performed, rather than the interval between successive tests or inspections. As a result, with the present definitions a monthly test could be performed at the beginning of one month and at the end of the following month, yielding an effective interval between tests of two months. Or, at the other extreme, tests could be performed on the last day of one month and the first day of the next month, yielding an interval between tests of one day. Clearly, either of these extremes would not meet the intent of performing the tests approximately one month apart. While records of inspections' indicate the licensee has maintained a high degree .

of conformance with the intent of the prescribed periodic surveillance, >

the potential for misinterpretation is present. Accordingly we requested, i and the licensee agreed to submit revised definitions for surveillance intervals.

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A definition of " Staggered Test Basis" is needed because this type of surveillance was specified for. the first time in Technical Specification 4.18.2 (Amendment No.18, February 14, 1978) without providing a definition for " Staggered Test Basis."

Evaluation The proposed revised definitions of time periods applicable to plant surveillance (Specification 1.9) are expressed in terms of the maximum length of the interval rather than in terms of a block of time. Accordingly, this will clearly define the m.ximum length of time between successive tests or inspections, subject to the tolerance limits permitted by the specifications. Because this effectively eliminates the possible misinterpretation of required surveillance intervals '

and maintains the intent of the surveillance schedule, we conclude that the proposed revised definitionsare acceptable. We have made certain changes in the licensee's submittal to assure completeness and eliminate repetition. These include the addition of a definition for an annual time period and the replace-

+25%) with tolerance limits as specified ment of the for plants presentbeing currently tolerance licensedlimits(+(75% for a single interval and no more than 3.25 times one interval for the period of three successive intervals). These changes have been discussed with and agreed to by the licensee, With regard to the definition of " Staggered Test Basis," the definition proposed by the licensee is substantially the same as that given in the Commission's Standard Technical Specifications for Babcock & Wilcox Pressurized Water Reactors.

The only difference between the two versionsis that the NRC's version calls for the surveillance to be performed at the beginning of each surveillance subinterval while the licensee's version calls for the surveillance to be performed during each surveillance subinterval. Since the purpose of specifying a staggered test basis is to assure that redundant safety related components are tested periodically but not simultaneously, and since the licensee's -version of the defin' tion meets this requirement, we cor"ude that the definition of " Staggered Test Basis" is acceptabl e.

Environmental Consideration We have determined chat the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 651.5(d)(4), that an environmental impact statement, or neaative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of this amendment.

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'l Conclusion -

I We have concluded, based on the considerations discussed above. .that.

, (1) because the amendment does not involve a significant increase.in the probability ~or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards consideration, (2) there is reasr"able assurance that the health and safety of the public will not be enuangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission'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. .

Dated: ' October 3,1978-

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