ML20065D245

Safety Evaluation Supporting Amend 45 to License NPF-62

ML20065D245
Person / Time
Site:	Clinton
Issue date:	09/17/1990
From:	Office of Nuclear Reactor Regulation
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ML20065D242	List: ML20065D239 ML20065D245
References
NUDOCS 9009250016
Download: ML20065D245 (6)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 1

RELATED TO AMENDMENT NO. 45 TO FACILITY OPERATING LICENSE NO. NPF-62 l

ILLI*' 'S POWER COMPANY. ET AL.

L CLINTON POWER STATION, UNIT NO. 1 DOCKET NO. 50-461

1.0 INTRODUCTION

Sy letter dated July 11; 1990 IllinoisPowerCompany,etal.(thelicensee) proposed three changes to the Technical Specifications for the Clinton Power Station, Unit 1.

The second of the proposed changes would modify Technical Specification 3.8.3.1 Action a.3.

That Action statement currently requires that, in the event that one of the inverters associated with panels 1C71-S001A, B, C, or D becomes inoperable, the associated distribution panel must be re-energized within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and the inverter must be restored to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or the plant must be shut down.

The licensee has requested that.the Action requirements for the inverters-associated with panels IC71-S001C and D be revised to only require that the High Pressure Core Spray (HPCS) system be declared inoperable and the Action requirements of Technical Specification 3.5.1, Emergency Core Cooling Systems Operating, be followed.

Operability of the DC Sources and Onsite Power Distribution Systems in general relies upon the availability of necessary support s include the essential switchgear heat removal (VX) ystems. These support systems system and the emergency shutdown service water (SX) system. These systems are separated into divisions similar to and consistent with the Emergenc

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EachVXsubsystem(DivisionI,II,orIII)yCoreCooling' Systems-(ECCS).

is a major' support system since each is designed to provide emergency heat removal capability in areas which contain the associated diesel generator (DG) station battery, battery char switchgear,andelectrical(NSPS)inverterassociatedwiththatdivision.ger, Each divisional VX area cooler contains a safety-related cooling coil that-can be supplied with emergency cooling water from the associated divisional SX subsystem. The area coolers are not normally supplied by SX cooling water, but during a loss of coolant accident (LOCA) or upon a loss of offsite power, cooling water is supplied solely by the SX system. The SX system is used to remove heat from equipment necessary to safe _1y: shut down the plant and maintain the plant in a safe shutdown condition.

The loads associated with the Division III SX subsystem are the Division III SX Pump Room Coil Cabinet.

DivisionIIIDieselGeneratorHeatExchanger,)DivisionIIIDieselSwitchgear Heat Removal Unit, and the Division III (NSPS Inverter Room Cooler.

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B On May 24, 1990,'the Division III SX pump failed to rotate in an attempted startup during an operability /IS1 surveillance test. The pump motor energized but tripped due to a trermal overload condition.

Corrective action taken included loosening the packing gland follower, meggering the motor 'and replec.ing the thermal overload protection devices; but the pump still required an elettrical

" bump" to get it to freely rotate..It was then rechecked and verified to be free to rotate by hand with no evidence of binding. The pump performance data taken while subsequently performing the surveillance test was satisfactory.

During the last performance of the pump operability / inservice inspection (ISI) surveillance test for the Division III.SX pump on August 17, 1990, it was again observed that the pump failed to rotate. The pump motor energized but soon tripped because of thermal overload protection.

The pump was freed again and verified to rotate freely.

Runningindications(vibration, temperatures, motor-amperage) are satisfactory, but the licensee will now consider the pump to be OPERABLE only while it remains running. Once the pump is shut down for investigation and/or repair, the current technica".zspecification require that the Division III SX subsystem will beideclared inoperable.

In accordance with the Action Statement under Technical Specification 3.7.1.1, with an SX loop inoperable, and with its associated systems or components required to be OPERABLE, the associated systems or components must be declared inoperable, and the ACTION (S) required for those inoperable systems or components must be taken.

Under accident conditions, the VX system is. incapable of performing its safety function without the SX system available; therefore the Division III VX cooler must be considered inoperable when the Division III SX subsystem is inoperable.

In turn, with the VX cooler inoperable,-the-licensee L

currently believes that at least-some of the electrical components in the area cooled by the VX cooler could not perform their intended safety function for a sufficiently long enough period of time.

The component most likely to be affected by the loss of the YX-' system and with which the most limiting Action Statement is associated is the NSPS ir.verters.

If the Division III NSPS inverter is considered' inoperable, Action a.3 under Technical Specification 3.8.3.1 requires that the associated distribution panel must be energized within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and:the inoperable inverter must be restored to OPERABLE and energized status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; otherwise a plant shutdown is required. Therefore, as a result of the cascading effect'of the inoperability i

l of the Division III SX pump, only a 24-hour allowed out-of-service is effectively permitted by_the plant Technical Specifications before the plant must be shut l

down.

However, the licensee estimates that at least I week would be required to uncouple and lift the pump motor, lift the pump itself, inspect the shaft and bearings, perform any required repairs / overhaul, reinstall the pump and motor, and perform post-maintenance testing.

Therefore, on September 12, 1990, the. licensee submitted a request that the previously-described Technical Specification change request for the ACTION associated with the Divisions III and IV-inverters be reviewed on an emergency basis.

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l 2.0 EVALUATION l

Part of.the electrin

'vstem for the Clinton Power Station consists of four

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divisional Nucle 3y em Protection System (NSPS) power supplies.

Each of r

these power supp... provides an~uninterruptible 120 VAC bus for certain safety-related lwas. Each of these busses is' fed t,y two alternate sources--primarily through a solid-state inverter which converts 125 VDC battery power to 120 VAC NSPS power, alternately through a 480V/120V transformer with a 120V/120V isolation transformer for noise isolation. A solid-state transfer switch is provided which would sense inverter fai_ lure and automatically switch to alternate power.

As previously noted, D (Divisions.III and IV).becong koperable is that the the Action required when'the Sovseters associated with panels IC71-S001C or associated distribution panel must be re-enerM xed with5n 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and the 1

inverter must be restored to operable states klein 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or the plant must be shut down. However, per Technical Specifications 3.8.2.1 and 3.8.3.1, when the 125VDC busses that feed the Divisions III and IV-inverters or the Divisions III and IV NSPS busses that are fed by the inverters are declared inoperable, then HPCS must be declared inoperable-and--the Action required by Technical Specification 3.5.1 must ta followedL (The actions required by TS 3.5.1 are dependent ~on the operatienal status of_all ECCS systems and not just HPCS).. The Action.for the Divisions. III and-IV' inverters is clearly inconsistent with the Actions raquired for both the busses feeding the inverters and the busses fed by tha inverters.' In-addition, if the Division III diesel generator is deciared> inoperable, Technical Specification 3.8.1.1-Action D requires the:liesel generator to be restored to operable status within 72 ' hours or-the I!PCS system must be declared inoperable.

In all cases, for Divisions III'and-IV, except for when the Divisions III or IV inverter is inoperable, the final action is,to-declare the HPCS inoperable.

q An examination of the loads' supported by the Divisions III and IV NSPS E

distribution panels indicates that trip units associated with.the Reactor' Protection System (RPS), End-of-Cycle Recirculation Pump Trip (EOC-RPT) system, and the Nuclear Steam Supply Shutoff System-(NSSSS).are included in addition to HPCS.

Each of the trip units in Division III or IV however, 1

4 represents only one of the four total channels provided for each function since a channel is provided in each of all four NSPS divisions for these i

functions.

In addition, unlike the Emergency Core Cooling System actuation logic, this logic is designed to trip (fail-safe) on a loss of power. The Action statements for all three of the trip systems allow up to two channels to be inoperable indefinitely as long as one channel is placed in the tripped condition. Therefore, it is sufficient to only. declare the HPCS system inoperablewhentheassociated'(DivisionIIIor-IV)inverterisdeclared inoperable since a loss of power does not adversely affect,the operability-ofethe remaining systems.

The staff has reviewed the licensee's analysis and justification for the proposed change to Technical Specification 3.8.3.1 Action a.3., to only require that the High Pressure Core Spray (HPCS) system be declared inoperable l

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4 and the Action requirements of Technical Specification 3.5.1 be followed when inverters associated with panels 1C71-S001C and D are inoperable and finds that analysis and justification acceptable. This action is consistent-with the primary design basis for Divisions III and IV electrical power (support of the HPCS system) and is consistent with other Action requirements pertaining to Divisions III and IV power supplies.

3.0 CHANGED CIRCUMSTANCES A Notice of Consideration.of Issuance of Amendment, Proposed No Significant

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Hazards Ccnsiderati'an. and Opportunity for Hearing was published in the Federal Register on September 5, 1990.

Comments were requested by October J

5, 1990. That notice provided, however, that the Commission could issue the subject amendment prior to the expiration of the thirty-day comment period if circumstances changed so that prompt action was required by the Commission, for example, to avoid a derating or shutdtwn.

The licensee has provided arguments with respect to the change in.

q circumstances related to the amendment request. The licensee has stated 1

l that the shutdown of the sump to effect repairs is necessary to avoid catastrophic failure of t1e pump. This is in accordance with the vendor i

recommendations. Should the pump fail catastrophically personnel could be-injured and the repairs to the pump would be greatly complicated. Therefore, the licensee planned to take the Division III SX pump out of service'to-l effect repairs at the earliest possible date.

Based on parts availability the planned date for repairs is September 17, 1990. The repairs to the pump are estimated to take 7 to 8 days. _ As previously. explained, the~ shutdown of the SX pump would require plant shutdown within 24. hours due to the cascading effect of the Technical Specifications.

' Therefore, the plant will' enter a TS Action Statement to require plant shutdown.if the TS change is not approved prior to September 18,-1990. With respect to why the. situation occurred and why-it could not be avoided, the licensee has stated that, until the' Division III l

SX pump failed to meet the licensee's acce)tance criteria during the August 17, 1990 testing, the' licensee believed that tie corrective action'taken in response to the May 24, 1990 test had been adequate to restore full operability.- Following the May 24, 1990 test problem, the licensee recognized the cascading effect of L

the Technical Specifications and submitted the subject change request on-July 11, 1990; however the licensee believea the corrective actions'taken had resolved 3

the problem with the SX pump.

Therefore, prior to-August 17, 1990, the~ licensee could not have foreseen the changed circumstances. The staff has. evaluated.the licensee's deccM otion of the change in circumstances associated with this amendment request ed has determined that the need for-immediate relief from the-Technical Specifications under consideration could not have been avoided and that a valid need exists.

4.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION

DETERMINATION The Commission's regulations in 10 CFR 50.92 state that the Commission may make i

a final determination that a license amendment involves no significant hazards considerations, if operation of the facility, in accordance with the proposed e---

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amendment would not:

(1) involve a significant increase in the probability or consequences of an accident previously evaluated, (2)~ create the possibility of a new or different kind of accident from any accident previously evaluated.

l or (3) involve a significant reduction in a margin of safety.

This amendment has.been evaluated against the-standards:in 10-CFR 50.92.

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does not involve a significant hazards consideration because :

(1) The proposed change does not involve a significant. increase in the probability or consequences of a previously evaluated i

accident. The proposed change to the' Action Statements for inoperable inverters are bounded by the Action Statements j

currently specified for the associated power distribution j

f system. Since the plant's response to an inoperable inverter would be no more limiting than its response 1o deenergization of the bus that the-inverter supports, 00 change to an accident has been identified.

In addition, Divisions III and.IV power is primarily_ dedicated to the High Pressure Core Spray (HPCS) system since the remaining safety functions supported by the Divisions III and IV inverters are j

fail-safe on a loss of power. Therefore, since the l

Technical Specifications currently contain provisions to' allow the HPCS system to be inoperable-for reasonable periods of time, and since the HPCS system is only one of several Emergency Core Cooling Systems capable of providing i-the required emergency core cooling function, the.

consequences of a previously evaluated accident have not l

changed.

3 (2) The proposed change does not involve'any changes to the plant design, nor does it involve an introduction of any new or different modes of operation.

On-this basis, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

(3) The proposed change does not involve any changes to the l

operation or design of the HPCS system.

The proposed change-l to the electrical inverter Action Statement'is consistent-with and bounded by the Action Statements currently specified for the uninterruptible 120 VAC bus to which the associated' inverter is dedicated.

Therefore, the proposed j

change does not involve a significant reduction in the margin of safety.

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1 Accordingly, the Commission has determined that this amendment involves no significant hazards considerations.

5.0 STATE CONSULTATION

The staff discussed this amendment request with representatives of the State of Illinois on September 13, 1990. The State of Illinois representatives had' no comments.

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6.0 ENVIRONMENTAL CONSIDERATION

This amendment

• involves a change to a requirement with respect to the instal-f lation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or a change to a surveillance requirement. The-staff has determined that the amendment involves no significant increase =in.the amounts and no s,gnificant change in the types of any effluents that may berelea,sedoffsiteandthatthereisnosignifIcantincreaseinindividual or cumulative occupational radiation exposure. The Commission has made a final no significant hazards consideration finding with respect to this amendment.

Accordingly, this-amendment meets the eligibility criteria'for categorical i

exclusionsetforthin10CFR51.22(c)(9)..Pursuantto10CFR51.22(b),no l

environmental impact statement nor. environmental assessment need be prepared in connection with the issuance of this amendment.

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7.0 CONCLUSION

L The staff has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the will not be endangered by operation in the pro)osed manner; and (2) public such activities will be conducted in compliance wit 1 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.

Prircipal Contributor: John B. Hickman,-NRR Dated:

September 17, 1990 i

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