ML20214M468

Safety Evaluation Supporting Amend 54 to License DPR-34

ML20214M468
Person / Time
Site:	Fort Saint Vrain
Issue date:	05/20/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20214M418	List: ML20214M415 ML20214M440 ML20214M468
References
TAC-63029, NUDOCS 8706010314
Download: ML20214M468 (3)

Text

.

/ 'o g UNITED STATES

.y 8 o NUCLEAR REGULATORY COMMISSION l

( WASHINGTON, D. C. 20655 f

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 54 TO FACILITY OPERATING LICENSE NO. DPR-34 PUBLIC SERVICE COMPANY OF COLORADO FORT ST. VRAIN NUCLEAR GENERATING STATION DOCKET N0. 50-267

1.0 INTRODUCTION

By letter dated September 24, 1986 (Reference 1), Public Service Company of Colorado (PSC) requested a change to the technical speci-fications for the Fort St. Vrain Nuclear Generating Station. The change involves surveillance recuirements for the emergency diesel generators (EDGs). The proposec changes remove load shedding and load sequencing from the semi-annual test and include it into the tests that are performed during the refueling outage. Some minor rewording for clarification is also included in this change.

2.0 EVALUATION The objective of surveillance of the EDGs is to verify design capa-bility of the onsite ac power system to perform its safety function.

At Fort St. Vrain, the EDGs are tested weekly, monthly, semi-annually, and during the refueling outage. The aroposed changes are in the semi-annual test and the test during tie refueling outage.

Presently, the semi-annual test (minimum and maximum interval between the tests is four months and eight months, respectively) is conducted by simulating a turbine trip and loss of offsite power to demonstrate that the EDGs, their automatic controls, and the associated load sequencers are operable. During power operation of the plant, starting an EDG automatically on a simulated loss of offsite power does not induce any transient or perturbation in the Class IE electric distribution system. However, the verification of the operability of the load sequencer causes separation of emergency buses from the offsite power source, load shed, and restarting of the loads on the onsite EDG power source. This may induce severe disturbance in the Class 1E electric distribution system, affecting normally operating equipment, and may cause the unit to trip. During plant operation, PSC believes that deliberately induced upsets should be minimized. Additionally, minimizing plant trip and restart enhances overall plant reliability and decreases challenges to the 8706010314 870520 PDR ADOCK 05000267.

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e safety systems. To avoid this potential risk, the licensee has pro- -

4 posed to remove verification of load sequencer operability from the semi-annual test schedule to once per refueling cycle, not to exceed 18 months. The licensee's proposal also includes conducting a once per refueling cycle test in lieu of the scheduled semi-annual test.

The staff finds it acceptable on the basis that the semi-annual test on the EDGs demonstrates the operability of the EDGs and its automatic controls, which is included in the once per refueling cycle test.

By removing the load sequencer operability test from six months to once per operating cycle, the EDG's full load testing shall also be once per refueling cycle. This is less conservative because the semi-annual test will no longer verify the capacity and capability of the EDGs for the full load operation. " General Design Criteria," GDC 18 of Appendix A to 10 CFR 50 requires periodic testing of the operability of a protective system as a whole and, under conditions as close to design as practical. In response to the staff's concerns, the licensee stated in Reference 2 that the EDGs are loaded to at least 1200 kW for a period of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> in the once per week test. The Technical Specification (Section 5.6.1.a) requires the EDGs to be loaded at 1210 kW) in the once per least test.

week 50%However, of their rated full load the PSC's capacity written surve -(illance procedure puts t i 1200 kW on each EDG in this weekly test. Additionally, PSC has sub-mitted, as a draft, a complete revision of the Fort St. Vrain Techni-cal Specifications which follows the standard Technical Specification format and will include full load testing of the EDGs during plant '

operation. In the interim, until the proposed draft Technical Speci-fication is approved by the NRC (expected approval time is about 1 year), the PSC surveillance procedure for full load testing of the  :

EDGs on a weekly basis is acceptable. The resident inspector's verifi-cation of the licensee's EDG weekly test procsNre is deemed sufficient during the interim period.

i The proposed change also includes increasing minimum allowable inter-val between the semi-annual test schedule from four months to six months. The maximum allowable interval between the semi-annual tests will remain to be eight months. However, the maximum combined time interval for three consecutive semi-annual tests shall not exceed 20 months. This is more conservative than the present allowance of i

maximum of 24 months as combined time interval for three consecutive '

semi-annually test on the EDGs. The staff finds this change to be conservative and, therefore, acceptable.

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3.0 ENVIRONMENTAL CONSIDERATION

The amendment involves a change in the installation or use of a facil-ity component located within the restricted area as defined in 10 CFR Part 20. The staff has determined that the amendment involves no

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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 previously issued a proposed finding that this amendment involves no significant hazards considera-tion and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 651.22(c)(9). Pursuant to 10 CFR 551.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

4.0 CONCLUSION

We have 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 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.

5.0 REFERENCES

(1) PSC letter, R. Williams, Jr. to NRC, H.N. Berkow, dated September 24, 1986. ,

(2) PSC letter, H. L. Bray to NRC, H.N. Berkow dated March 25, 1987.

Dated: May 20, 1987 Principal Contributor: I. Ahmed

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