ML20149L696

Safety Evaluation Supporting Amend 95 to License DPR-54

ML20149L696
Person / Time
Site:	Rancho Seco
Issue date:	02/12/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20149L688	List: ML20149L686 ML20149L691 ML20149L696
References
NUDOCS 8802240389
Download: ML20149L696 (3)

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1. 3 ElCp\ UNITED STATES 8 w g NUCLEAR REGULATORY COMMISSION )

;j W ASHING TON, D. C. 20555

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.95 TO FACILITY OPERATING LICENSE OPR-54 SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING STATION, UNIT 1 DOCKET N0. 50-312 1.0 3'TR000CTION By letter cated May 14, as revised and supplemented September 25 and October 29, 1987, the Sacramento Municipal Utility District (the licensee) requested several changes to the plant Technical Specification (TS) for Rancho Seco Nuclear Generating Station, Unit 1. The proposed TS changes include the l additionofSections3.30and4.35regardingtheoperabilityandsurveillance requirements for the hydrogen recombiners,A and the deletion of Section 4.4.3,

, concerning surveillance for the hydrogen purge system. These TS changes corre-spond to the plant modification for addition of hydrogen recombiners to be installed in the containment as a replacement for the existing hydrogen purge system for post-accident (LOCA) combustible gas control.

The September 25 and October 29, 1987 submittals provided clarifications to the original request and did not substantially alter the action noticed, or the staff's initial determination published, in the Federal Register on August 26, 1987.

2.0 EVALVATION 10 CFR 50.44(b)(3) requires that plants have the capability of controlling l combustible gas concentrations in the containment following a postulated LOCA.

The licensee indicated that the purpose of the plant modification was to improve i the operational reliability and maintainability of the combustible gas control system. The internal hydrogen recombiners will provide almost five times the hydrogen removal capability of the existing hydrogen purge system and operate j without the need for venting the containment environment to the atmosphere. l The recombiners are actuated at the same concentration limit of 3.5 v/o as the replaced hydrogen purge system. The installation of internal recombiners will upgrade the post-accident hydrogen control capability but will not affect the existing hydrogen measurement features or containment atmosphere mixing provisions, d

U The TS provisions were originally numbered 3.29 and 4.33, respectively, however, the staff has renumbered them TS with the issuance of this amendment to reflect the addition of TS provisions by other amendments.

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2-1 The Westinghouse hydrogen recombiners proposed for installation are designed in accordance with 10 CFR 50 Appendix A, and the guidelines of Regulatory Guide 1.7, "Control of Combustible Gas Concentrations in Containment Following a Loss of Coolant Accident." In addition, the hydrogen recombiners will be installed in accordance with the guidelines of Regulatory Guide 1.7 and the quality assurance requirements in 10 CFR Part 50, Appendix A. The recombiner systems are redundant and independent. Each recochiner is powered by a separate onsite emergency power supply. The recombiner installation is also designed to withstand the Rancho Seco Design Basis Earthquake without loss of function.

The installation of the recombiners pemits periodic inservice inspection and operability testing. Proposed TS Sections 3.30 and 4.35 specify the recombiner operability and surveillance requirements in accordance with the Standard Technical Specifications (STS) for Babcock and Wilcox PWRs. Tha staff finds the proposed installation of the hydrogen recombiner system as a means for '

hydrogen control and the corresponding proposed TS Sections 3.30 and 4.35 meet the criteria of Regulatory Guide 1.7.

As a result of the installation of the hydrogen recombiner system, the licensee proposed to delete TS Section 4.4.3, Surveillance Standards for Hydrogen Purge System. However, despite such a change, it is reconinended in Regulatory Guide -

1.7 that the installed capability for a controlled purge of the containment atmosphere be maintained in order to aid in post-accident cleanup / hydrogen control. The licensee indicated in its letter of October 29, 1987 that a

hydrogen purge capability is available by use of the normal containment purge and pressure equalization systems. These systems are under surveillance per Section 4.11 of the Rancho Seco TS. The containment pressure equalizing valves can ba opened to reduce containment pressure before purging the containment.

The normal containment purge isolation valves are closed with their breakers de-energized during norinal operation; however, the system can be made opera-tional when required. Both systems exhaust to the reactor building exhaust stack which is monitored by a high range noble gas effluent monitor. The l availability of these systems serve as suitable alternative means for post-accident cleanup / hydrogen control capability, and thus deletion of TS 4.4.3 '

is acceptable.

3.0 CONCLUSION

S Sunenary Based on the above, the staff cosludes that installation of the hydrogen recombiners satisfies the requirements of 10 CFR 50.44 and the proposed addition of TS Sections 3.30 and 4.35 and deletion of TS Section 4.4.3 are in accordance with the guidelines of Regulatory Guide 1.7. Therefore, the proposed changes are acceptable.

i Contact With State Official l The NRC staff has advised the Chief of the Radiological Health Branch, State 1

Department of Health Services, State of California, of the proposed determina-

) tion of no sigaificant hazards consideration. No cosinents were received.

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3 Environmental Consideration This amendment involves changes in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.

The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that mdy 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 consideration and there has been no public connent on such finding. Accordingly, this amendment neets the eligibility criteria for categorical exclusion set forthin10CFR51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

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 (3) the issuance of the amendment will not be inimical to comnon defense and security or to the health and safety of the public.

Principal Contributors: C. Y. Li Dated: February 12, 1988 i

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