ML20211J095

Safety Evaluation Supporting Amend 81 to License DPR-54

ML20211J095
Person / Time
Site:	Rancho Seco
Issue date:	04/17/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20211J073	List: ML20211J068 ML20211J078 ML20211J095
References
TAC-57587, NUDOCS 8606260180
Download: ML20211J095 (4)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT N0 81 TO FACILITY OPERATING LICENSE NO. DPR-54 SACRAMENTO MUNICIPAL UTILITY DISTRICT

RANCHO SEC0 NUCLEAR GENERATING STATION DOCKET N0; 50-312 INTR 01)UCTION By letter dated April 15, 1985, as modified September 6, 1985, Sacramento j Municipal Utility District (SMUD or the licensee) requested amendment to the Technical Specifications (TSs) appended to Facility Operating License No.

DPR-54 for the Rancho Seco Nuclear Generating Station (RS). The proposed ,

amendment would modify the methods used for periodic testing of portions of the emergency power system.

aBACKGROUND TNFORMATIG;.

By letter dated February 2, 1981, the licensee proposed a number of revisions to the TSs applicable to the emergency electrical power system. The proposed revisions were made in response to an NRC letter of June 3, 1977, addressing degraded grid voltage protection. The proposed revisions to the TSs were reviewed and found acceptable by the NRC staff, and issued by the NRC as 4 Amendment No. 46 to the facility license.

EVALUATION

a. Specification 4.6.2.A(3)

The licensee proposes to revise the wording of this paragraph and assign it paragraph number 4.6.2.B. Current paragraph 4.6.2.8 will be j unchanged except for being renumbered 4.6.2.C.

! The reason the licensee has requested this change is because "The exact method (of testing) outlined in TS 4.6.2.A(3) cannot be applied due to the design of the emergency power system." In explanation, the licensee notes Specification 4.6.2.A requires testing be done by " Simulating a loss of offsite power in conjunction with a safety features actuation

. signal....", and subparagraph (3) requires, " Verifying that on ,

diesel-generator trip, the load shedding circuitry operates properly and i the diesel restarts on the auto-start signal." The licensee says the

system design does not support this method of testing because imposition 1 of a safety features actuation signal, as presently required,' blocks all automatic and manual shutdown trips of the diesel generator except for i engine overspeed, generator differential current and generator ground current, and the manual Emergency Stop capability. Thus, short of simulating one of the unblocked major faults, the only direct means available for " tripping" the diesel generator is to use the Emergency I

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-2 Stop capability. This, however, is not satisfactory for this test because it " seals in" the shutdown, and the diesel cannot be restarted automatically as required by the present specification until the shutdown has been reset manually using a local reset pushbutton.

A representative of the licensee states the " trip" requirement has been implemented in the past by initiating a " normal shutdown" of the diesel which still permits auto-start as required by the present specification.

(It is noted, however, a normal shutdown does involve operation at idle speed for a period of 15 minutes for purposes of cooldown, prior to final stop. This is done to minimize thermal stresses that would otherwise be imposed on the diesel). Upon analyzing this matter, the licensee has concluded the present test method does not fully meet the intent of the present specification.

Upon performing additional analysis, however, the licensee has also concluded the present specification goes beyond the regulatory requirement set forth in the letter from the NRC to the licensee dated June;3, 1977. The guidance cited by the licensee is Position 3: Onsite Power Testing. This Position states nas follows: "We require that thr Technical Specifications ~ include a test requirement to demonstrate tne full functional operability and independence of the onsite power sources at least once per 18 months during shutdown. The Technical Specifications shall' include a requirement for tests: (1) simulating loss of offsite power in conjunction with a safety injection actuation signal; and (2) simulating interruption and subsequent reconnection of onsite power sources to their respective buses. Proper operation shall be determined by:

"a) Verifying that on loss of offsite power the emergency buses have been de-energized and that the loads have been shed from the emergency buses in accordance with design requirements.

"b) Verifying that on loss of offsite power the diesel generators start from ambient condition on the autostart signal, tha emergency buses are energized with permanently connected loads,

, the auto-connected emergency loads are energized through the load sequencer, and the system operates for five minutes while the generators are loaded with the emergency loads.

"c) Verifying that on interruption of the onsite power sources the loads are shed from the emergency buses in accordance with design requirements and that subsequent loading of the onsite sources is through the load sequencers."

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The licensee states the present specification exceeds regulatory requirements because Item c of the above position does not require tripping of the diesel generator, but merely " interruption of the onsite sources". Based on this, the licensee proposes to open the diesel generator output breaker, without tripping the diesel engine. Even this action, however, is blocked if a safety features actuation signal (SFAS) is present. The licensee, therefore, proposes, after satisfying the requirement to simulate a loss of offsite power in conjunction with an SFAS, to reset the SFAS thereby allowing the diesel generator output '

circuit breaker to be tripped.

Based on the foregoing considerations, the licensee has proposed revised Specification 4.6.2.B. which does not require " tripping" of the diesel generator on a coincident loss of onsite power combined.with an SFAS.

Regarding the acceptabiity of the licensee's proposal, we note the NRC letter of June 3,1977 - which set forth Position 3 - also transmitted model TSs. We also note the licensee's present TSs closely follow the guidance given in the model. Based on our review of the model TSs, we

. conclude they impose testing requirements beyond those stated r

~ Position 3. Confiming this is the fact the current Standard TSs (tc

, issued for recently licensed plants, and as set forth in NUREG-0103, Rev.

! 4) de not require " tripping" the diesel generator under the conditions covered by this specification; nor do the Standard TSs require shutdown and restart of a diesel following a simulated loss of offsite power in conjunction with a SFAS.

Based on the foregoing considerations, we conclude the proposed revised specification acceptably meets the. guidance contained in Position 3, as stated in Enclosure 1 to the NRC letter to the licensee dated June 3, 1977, and is in satisfactory conformance with the corresponding guidance contained in the Standard TSs. Accordingly, we find the proposed revised specification acceptable,

b. Specification 4.6.2.B As noted' above, no changes are proposed for present Specification 4.6.2.B other than changing the paragraph number to 4.6.2.C to accommodate the proposed revision of paragraph 4.6.2.A(3). . We conclude this is an editorial change and is acceptable.

ENVIRONMENTAL CONSIDERATION P

This amendment involves a change in a surveillance requirement. We have 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 previously issued a proposed finding that this amendment involves no significant hazards consideration 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 51.22(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.

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. l 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.

Dated: April 17, 1986 Principal Contributor: G. Zwetzig O

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