ML20247Q895

Discusses Reactivity Coefficients Test at Power Scheduled to Be Performed Between 258 & 300 EFPDs to Provide More Accurate Reflection of end-of-cycle Core Behavior.Plant Core Will Reach 258 EFPDs on or About 890613

ML20247Q895
Person / Time
Site:	Rancho Seco
Issue date:	05/24/1989
From:	Croley B SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
AGM-NTS-89-123, NUDOCS 8906070077
Download: ML20247Q895 (2)

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)SMUD SACRAMENTG MUNICIPAL UTtuTV DISTRICT O 6201 S Street, P.o. Box 15830, Sacramento CA 958d21830, (916) 452 3211 AN ELECTRIC SYSTEM SERVING THE) HEART OF CALIFORNIA oc mW y AGM/NTS89-123 U I N 2 8 .t10 : 0 8 May 24, 1989 U. S. Nuclear Regulatory Commission Attn: J. B. Martin, Regional Administrator Region V 1450 Maria Lane, Suite 210 Halnut Creek, CA 94596 Docket No. 50-312 Rancho Seco Nuclear Generating Station License No. DPR-54 REACTIVITY COEFFICIENTS TEST AT POWER

Dear Mr. Martin:

The reactivity coefficients test at power, RT-RCS-014, is scheduled to be performed between 258 and 300 Effective Full Power Days (EFPD). This will ensure the RCS boron concentration is less than.300 ppm, which is the test condition required by Standard Technical Specifications. Performing this test closer to the end-of-cycle provides a more accurate reflection of the end-of-cycle core behavior, the core condition of interest. At a constant power level of 92%, the Rancho Seco core will reach 258 EFPD on or about June 13, 1989.

When performed at the beginning-of-life, RT-RCS-014 provides assurance that the temperature coefficient is negative as assemed for the accident analysis.

The primary purpose of the subject test, however, is to provide additional assurance, beyond core design assurances, that- the end-of-cycle temperature coefficient is conservative compared to the USAR steam line break analysis.

This testing also provides feedback for- fine tuning the core design models.

Although the subject test is included in Rancho Seco's startup test program described in the Reload Report, reactivity coefficient testing at power is not included in the required scope of ANSI /ANS 19.6.1-1985, " Reload Startup Physics Tests for Pressurized Hater Reactors."

Based on observed core behavior and the design relationship between reactivity coefficients and core burnup, adequate margin to the USAR analysis exists before 300 EFPD. The Rancho Seco core is designed for 335 EFPD. Additional margin to the USAR analysis is also provided by operating at 92% power.

pgPTe8gassag2 Jgof I o RANCHO SECO NUCLEAR GENERATING STATION O 14440 Twin Cities Road, Herald, CA 95638-9799;(209) 333-293 >

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- 3.18. Martin AGM/NTS89-123 Members of your staff with questions requiring additional information or clarification may contact Mr. Jerry Delezenski at (209) 333-2935, extension 4914.

Sincerely,

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Bob G. Croley Assistant General Manager Nuclear Technical Services cc: A. D'Angelo, NRC, Rancho Seco Document Control Desk, Washington DC l

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