ML20236X111

Safety Evaluation Supporting Amend 90 to License DPR-54

ML20236X111
Person / Time
Site:	Rancho Seco
Issue date:	11/13/1987
From:	Office of Nuclear Reactor Regulation
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ML20236X107	List: ML20236X105 ML20236X108 ML20236X111
References
NUDOCS 8712080429
Download: ML20236X111 (4)

Text

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SAFETY EVALUATION BY THE OFFICE,0F NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 90 TO FACILITY OPERATING LICENSE NO. DPR-54 SACRAMENTO MUNICIPAL UTILITY DISTRICT RANCHO SECO NUCLEAR GENERATING STATION DOCKET NO. 50-312

1.0 INTRODUCTION

On August 13, 1986, the Commission issued to Sacramento Municipal Utility District (the licensee) Amendment 82 to Facility Operating License

.No. DPR-54. This amendment incorporated Low Temperature Overpressure Protection (LTOP) criteria into the Technical Specifications (TS).

Subsequently it became evident that Amendment 82 was deficient in not providing for venting and surveillance testing of the LTOP system. 'By letter dated April. 23, 1987 the licensee request an amendment to correct this deficiency in Amendment 82. Additionally, the licensee requested specific minimum flow rate' criteria for the emergency heating, ventilation,.

and air conditioning (HVAC) system in the Nuclear Service Electric.

Building (NSEB).

The LTOP and HVAC TS changes were evaluated separately and are addressed below. The Safety Evaluation (SE) related to LTOP included under Section 1

2.0 and the HVAC SE is ' included under Section 3.0.

2.0 Evaluation Relating To Technical Specification Changes For The Low Temperature Overpressure Protection As stated above, License Amendment No. 82 dated August 13, 1986 incorporated requirements for the operation of the Low Temperature Overpressure Protection System (LTOPS) into the Rancho Seco.TS. However, I

inadvertently, these new TS did not allow filling and venting the reactor coolant system (RCS) or for periodic maintenance. To make these allowances-l and to more clearly define the LTOPS enabling operation, SMUD proposed in its April 23, 1987 submittal to add five subsections to TS 3.2.2. and two paragraphs.to its Bases. These subsections are 3.2.2.1.1, 3.2.2.2.1, L

3.2.2.2.2, 3.2.2.2.3, and 3.2.2.5.1.

one of the added paragraphs in the i

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Base injection lines filling; the other concerns concerns the maintenance and surveillance testing of the Core Flood System.

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Subsection 3.2.2.1.1 would define the LTOPS enabling operation.

Subsections. 3.2.2.2.1, 3.2.2.2.2 and 3.2.2.2.3 would make=it possible to i

fill and vent the. injection lines without violating the TS and subsection 5

3.2~.2.5.'1 would. allow maintenance and surveillance testing on the Core 1

Flood System.

For the filling and venting'of the injection lines, only one of the motor.

operated valves in the High Pressure Injection (HPI) system may open at-any time. During the filling and venting, all HPI-Makeup pump breakers.

shall be racked out and tagged. Nitrogen overpressure in the Makeup tank.

provides the motive force for fluid flow during the filling and' venting.

This overpressure is limited by a relief valve on the Makeup. tank. This is set at 100 psig, which is insufficient to cause a low temperature overpressurization.

q When the Core Flood Tank pressure is below 500 psig, which is the setpoint for the Low Temperature Overpressure Protection System, water from this tank cannot cause a low temperature overpressurization.

Since there is no need to. maintain the core flood discharge valves closed, the licensee proposed to revise TS to allow the: discharge valves to remain open or be opened below 500 psig.

The staff finds that there are sufficient precautions in the proposed subsections to make a low temperature overpressurization highly unlikely l

during the filling and venting of the injection lines and during.the I

maintenance and testing of the Core Flood System. Therefore, the staff concludes that the Sacramento Municipal Utility District's proposed changes to Rancho Seco Technical Specification 3.2.2 are acceptable.

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3.0 EVALUATION RELATING TO TECHNICAL SPECIFICATION 4.31, " NUCLEAR SERVICE ELECTRICAL SUILDING EMEE6tNGY HEALING VENTILATION AND AIR LONDlIIONING" By letter dated April 23, 1987, the licensee proposed an amendment to l

revise Technical Specification 4.31, " Nuclear Service Electrical Building i

Emergency Heating Ventilation and Air Conditioning". The purpose of the proposed revision is to establish a minimum flow rate requirement for Nuclear Service Electrical Building (NSEB) emergency Heating Ventilation and Air Conditioning (HVAC) air handling unit to be used in place of the present value with its minimum /maxirrum to tolerance. The proposed revision would change the wording from "...a flow rate of 24,500 cfm 10 i

percent" to "...a minimum flow rate of 24,500 cfm," and would revise the wording in the Bases from "The air flow of 24,500 cfm..." to "The minimum air flow of 24,500 cim..".

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i NSEB houses nuclear service batteries, switchgear, battery chargers, and the necessary electrical equipment required to support.the TSC, control room, and the HVAC system.

The NSEB is served by nonnal-essential (backup) ventilation systems. The normal system consists of two air conditioning units, two normal:

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return exhaust fans, two ventilators, and one unit heater. The essential system is made up of two condensing units and two direct expansion coils with a supply fan. The minimum design capacity of the NSEB essential HVAC fan is 24,500 cfm. The licensee stated that the proposed change would ensure that the surveillance standards for the NSEB emergency HVAC unit agree with technical specification bases for system performance.

The licensee stated the following in the support of the proposed change for the NSEB Emergency HVAC air handling unit to maintain the minimum flow rate of

-24,500 cfm:

"This air flow rate was selected to limit the temperatures in the NSEB building to 80 F maximum. Air flow is verified once per 31 days by initiating flow through the essential air handling unit. This amendment changes the tolerance on the unit by eliminating the t[10] percent condition and. requiring a minimum of flow rate of 24,500 cfm as specified in technical specification bases. A higher flow rate will enhance the i

capability of the system to maintain the designed temperature in the NSEB

[to ensure adequate cooling]. Any noise resulting from hi l

is not a factor since it is not a normally occupied area. gher flow rates Therefore, this change has no effect on the safety function of the NSEB air handling unit."

Additionally, the licensee stated that this change has no effect on the safety function of the NSEB Emergency HVAC, and it does not introduce a new failure mode, involve any accident previously evaluated, nor reduce any margins of safety.

The staff has reviewed the above change and supporting rationale and concludes

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that the proposed charge to the NSEB HVAC surveillance standard more clearly I

specifies the required flow rate, and it eliminates the tolerance in flow rate, which agrees with technical specification base.

Based on the above, the staff concludes that the proposed change places a minimum flow requirement, which is more ennservative in nature, on the NSEB emergency HVAC system and will not have any adverse effects on plant opera tion. The staff, therefore, finds the proposed NSEB Emergency HVAC system technical specification change acceptable.

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4-r 4.0._ CONTACT WITH STATE OFFICIAL I

The NRC staff has advised the Chief of the Radiological Health Branch, State Department of Health Services, State of California, of the proposed determination of no significant hazards consideration. No comments were received.

5.0 ENVIRONMENTAL CONSIDERATION

The amendment involves changes in the installation or use of facility components located within the restricted area.

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 may be released offsite and that there is no significant increase in individual or cumulative occupation radiation exposure. The Commission has previously

. issued proposed findings that the amendment involves no significant hazards consideration, and there has been no public comment on such finding. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Sec. 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment needs to be prepared in connection with the issuance of the amendment.

6.0 _ CONCLUSION Based upon our evaluation of the proposed changes, we have concluded that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted _in compl1ance_with:the. Commission's -

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

We, therefore, conclude that the proposed changes are acceptable.

Principal Contributors:

E. Lantz J. Raval Dated:

November 13, 1987 i

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