ML20148P404

Insists Subj Facil ECCS Is Acceptable & in Conformance W/ 10CFR50.46,but in Response to Staff Request Util Applies for Exemption to 10CFR50.46 & for Lic to Oper at 2772 Mwt for Duration of Cycle 3.Will Provide Details of Mod

ML20148P404
Person / Time
Site:	Rancho Seco
Issue date:	11/22/1978
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Reid R Office of Nuclear Reactor Regulation
References
NUDOCS 7811280209
Download: ML20148P404 (3)

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'$)SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 s street, Box 15830, sacramento, California 95813; (916) 452-3211 November 22, 1978 Director of Nuclear Reactor Regulation Attention: Mr. Robert W. Reid, Chief Operating ~ Reactors, Branch No. 4 U. S. Nuclear Regulatory Conmission Washington, D. C. 20555 Docket No. 50-312

. Rancho Seco Nuclear Generating Station, Unit No.1

Dear Mr. Reid:

On April 14, and 21, 1978, the Sacramento Municipal Utility District informed you of an apparent error in the B&W Small Break ECCS-Analysis applicable to Rancho Seco Nuclear Generating Station, Unit No. -1.

On July 7, and 18,1978, we provided analyses and operating procedure changes to assure safe operation of Rancho Seco Unit No.1 at full rated power (2772 MWt core power) in full compliance with the provisions of 10 CFR 50.46. In addition, on July 13, 1978 we requested an amendment to Facility Operating License DPR-54 to assure the existence of the procedures for the necessary operator action required for this compliance.

In response to these submittals, the Commission issued an Order of Modification of License which amended the Rancho Seco Unit No.1 operating license on July 21, 1978. This order stated that operation in accordance with the operating procedures specified would assure that the ECCS will conform to the performance requirements of 10 CFR 50.46(b) and that such procedures provide reasonable assurance that the public health and safety ,

will not be endangered.

! It continues to be our position that the Rancho Seco Unit No.1 ECCS is currently acceptable and wholly in conformance with 10 CFR 50.46; however, your staff has requested that we file a request for exemption from 10 CFR 50.46 until further improvements to the ECCS can be made. It is not feasible to implement these modifications prior to the start-up of Rancho Seco Unit No.1 for Cycle 3 operation.. We can, however, commit to implement these modifications prior to the start-up for Cycle 4 operation. Therefore , ,

in response to the staff's request, it is hereby requested that an exemption be granted to the provisions of 10 CFR 50.46 and that Rancho Seco Unit No.1 be licensed to operate to a steady state power level of 2772 MWt for the duration of Cycle 3. This request is in the public interest because the

absence of this exemption would result in the loss of a large block of power j and a reduction of electrical power reliability in the District's service area. Since this request is being made in response to your request so that the conditions of your previous order may remain in effect, it is not subject to the fees specified in Paragraph 170.22.

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AN ELECTRIC SYSTEM S E R VI N G MORE THAN 600,000 IN THE HEART OF O A LI F O R N I A

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• Mr.' R. W. Reid Noverter 22, 1978 i

The improvements mentioned above were described in the District's ,

letter of July 20, 1978 and consists of modifications to eliminate the need i for operator action. You advised us on August 16, 1978 that you found this i concept acceptable. Formal approval is, of course, dependent upon your l detailed review of several considerations. At this time, we can commit to J environmental and~ seismic qualifications of new components and to the i availability of a battery loading analysis and preoperational test programs '

for your review. These details will be provided to you prior to implementa-tion.  ;

By letter dated September 26, 1978, you presented a staff position regarding allowable operator actions for which credit may be taken following l a small break. We responded on October,9,1978 stating that our proposed  ;

modification does not require any operator action to initiate adequate high pressure injection flow to each injection line. However, the. possibility of pump runout in a few instances has lead to discussions with your staff.which have resulted in a commitment on our part to provide throttling by means of -

' an electrical limit switch. Operating considerations make it desirable for.

the operator to be able.to provide full HPI flow to provide level control following a reactor trip. We therefore propose to provide an . electrical limit switch which will provide throttling sufficient to prevent HPI pump runout only with a safety features signal. An electrical schematic of this control scheme is attached. The District has experience with such a scheme utilized on the pressurizer spray valve at Rancho Seco Unit No.1. The limit switch is mechanically' driven preventing drift and the valve's open position has been demonstrated to.be extremely reliable. Assurance that the required l flow can always be achieved will be demonstrated during the testing of this ,

device when installed.

If you have any further questions concerning this modification, 4 please contact us.

Sincerely yours, hu &

J/ J. Mattimoe -

Assistant General Manager and Chief Engineer Attachment i Ic 7 T

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