ML20245D231

Safety Evaluation Supporting Amend 120 to License DPR-40

ML20245D231
Person / Time
Site:	Fort Calhoun
Issue date:	04/14/1989
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20245D208	List: ML20245D204 ML20245D226 ML20245D231
References
NUDOCS 8904280169
Download: ML20245D231 (3)

Text

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'[p uay%, UNITED STATES f g NUCLEAR REGULATORY COMMISSION 5 wAssincrow. o. c. rosss

%.....)ta SAFETY EVALUATION BY THE.0FFICE OF NUCLEAR. REACTOR REGULATION RELATED T0 AMENDMENT.WO.120 T0 FACILITY CPERATING. LICENSE.NO..DPR-40 OMAWA PUBLIC POWER DISTRICT FORT CALHOUN STATION, UNIT.NO. 1 DCCKET NO. 50-285

1.0 INTRODUCTION

By letter cated December 31, 1988 15, 1989, Omaha Public Power District (OPPD, as supplemented

) submitted on March an application for an amendment to Facility Operating License No. DPR-40 that would modify the Fort Calhoun Station, Unit No. 1. Technical Specifications to change the minimum operating requirements of the Raw Water Pumps. Plant operation '

could contigue with one pump jnoperable when the river water temperature is below 60 F. When above 60 F, the inoperable pump must be restored to operability within seven days.

2.0 DISCUSSION The present Technical Specification 2.4, Containment Cooling, allows one raw water pump to be inoperable indefinitely. However, a discrepancy exists in that the Updated Safety Analysis Report (USAR) states that a .,

minimum of two raw water pumps are required to provide sufficient flow to the component coolir.g heat exchangers to effect safe plant shutdown.

During a design basis loss of coolant accident with concurrent loss of off-site power and failure of a diesel generator, it is then possible that only one raw water pump would be operable.

The Raw Water System provides the cooling medium for the component coolito water (CCW) system. The basis for the operation of the raw water system during a design basis accident relates to the maintenance of sufficient containment cooling to limit containment pressure below the design value.

Containment heat removal is attained via the containment cooling coils and CCW system and heat exchangers to the raw water system. However, the containment spray system also provides redundant heat removal capability with the containment air recirculation and cooling system.

The calculations presented to support the proposed change to the TS were basedontheabilitytoremovethedesignheatloadwhflemaintainingthe designlimitsofmaximumCCWregurntemperatureof120Fandmaximumraw water return temperature of 210 F from aeing exceeded. The analysis used the assumptions of two containment cooling and filtering units and one containment cooling unit which is in excess of that necessary to provide a 6

containment heat removal of 280 x 10 BTU /hr. This containment fan cooler configuration would not exist if a diesel generator is assumed to fail to j i

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~2-start. In that case only one cooling and filterin units (operating with power from the swing busses)g unit would beand two cooling available.

However, the combined heat removal capacity for this configuration is essentially the same. For the situation with only one diesel generator i available, the USAR analysis assumes that only one cooling and filtering l unit and one cooling unit would be operable which does not provide the  :

design basis heat removal rate. Thus, the remaining heat removal capability would be received from the containment spray system operation.

The licensee's calculations indicate that a single raw water pump operating with a total gischarge flow rate of 6000 gpm and with river water temperature of 60 F would be suffigient to provide the removal of the design basis heat load of 285.1..x 10 BTU /hr from the CCW system.

This heat load removal is sufficient to prevent the containmerit design pressure from being exceeded while providing sufficient cooling to other i specified equipment coolers. The CCW system also provides cooling to the shutdown cooling heat exchangers but this flow is not established until a Recirculation Actuation Signal is initiated which occurs at a time when the containment cooling loads are significantly less.

J The raw water pumps are vertical, mixed flow pumps with a normal design ,

capacity of approximately 5400 gpm. In the single pump configuration during a DBA event, the single pump head capacity curve indicates that a flow of about 6600 gpm can be expected, which will be operation in  !

excess of the pump's best efficiency point. This situation is moderated-for the mixed flow irpeller/ pump since it provides a flatter power curve

. which tends to prevent pump and driver overload. However, the licensee has interfaced with the pump manufacturer to ensure that long term operation (e.g.1-2 days)atthesehigherflowswouldnotcausedegradationtothe pump. The raw water system has also experienced backflow through the pump discharge check valves. As added assurance that this will not present a problem, the pump air-operated discharge valves shut when the pump is not 1 operating. )

The proposed change to TS 2.4 will restrict the allowable operation with '

onerawwaterpumpindefinitefyinoperabletothoseperiodswhenriver water temperature is below 60 F. The analysis of this operatin 4 condition shows that a sufficient margin is present with this li iting I river water temperature for the raw water flow that is expected in single pump operation. This will ensure that the required heat removal rate is achieved while mairitaining the constraints associated with maximum CCW and raw water return temperatures. Thus, the staff finds the proposed change to the raw water pump operability requirements to be acceptable.

3.0 ENVIRONMENTAL. CONSIDERATIONS This amendment involves a change in the installation or use of a facility component located within the restricted area 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 may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The L i _ _ _ ___ _ _ _ _ _ - - . . _- - - - - - - - - - _ _

.j Commission has previously published a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such. finding. Accordingly, the amendment meets the eli criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9)gibility Pursuant to 10 CFR 51.22(b), no environmental impact statenant or environ-mental assessment need be prepared in connection with'the issuance of the amenenent.

4.0 _ CONCLUSION The NRC staff has concluded, based on the consideration discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by cperation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amencaent will not be inimical to the ".

comraon oefense and security or to the health and safety of the public.

Date: April 14, 1989 Principal contributor: P. Milano  !

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