ML20248B234

Application for Amends to Licenses DPR-24 & DPR-27, Consisting of Tech Spec Change Request 132,revising Tech Specs to Establish Limiting Conditions for Operation for Safeguards Buses in Electrical Distribution Sys

ML20248B234
Person / Time
Site:	Point Beach
Issue date:	09/22/1989
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20248B240	List: ML20248B234 ML20248B258
References
CON-NRC-89-110 VPNPD-89-497, NUDOCS 8910030141
Download: ML20248B234 (5)

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WNSCOMSin Elecinc areown 231 W. MICHIGAN P.O. BOX 2046,MtLWAUKEE,WI53201 (414:221 2345:

'VPNPD-89-497 10 CFR 50.59 l

NRC-89-110 September 22, 1989 H

l- .U. S. NUCLEAR REGULATORY COMMISSION Document Control Desk Mail Station P1-137 Washington, D. C. 20555 Gentlemen:

DOCKETS 50-266~AND 50-301 TECHNICAL SPECIFICATION CHANGE REQUEST 132 LCO'S FOR POWER DISTRIBUTION ON SAFEGUARDS BUSES POINT BEACH. NUCLEAR PLANT, UNITS 1 AND 2 In accordance with the requirements of 10 CFR 50.59(c) and 50.90, Wisconsin Electric Power Co'apany (Licensee) requests amendments to Facility Operating Licenses DPR-24 and DPRa27 for Point Beach Nuclear Plant, Units 1 and 2,-respectively, to incorporate changes.to Technical Specification Section 15.3.7,

" Auxiliary Electrical Systems." The changes establish Limiting Conditions for Operation (LCO's).for sateguards-buses in the Point Beach Nuclear Plant. electrical distribution system.

Technical Specification pages containing these proposed changes, which are~ identified by margin bars, are attached.

On October 26, 3988, emergency diesel generator GO1 was inadvertently removedifrom service while two 480 volt AC safeguards buses were tied together. This resulted in three of four 480 volt AC safeguards' buses becoming technically

. inoperable due to the unavallebility of the emergency power source-(G01). The duration of the inoperability~was approximately 43 minutes ~in 3ength, and a red phone notification was made. The details of the incident were reported in Licensee Event Report.(LER) 88-010-00 and LER 88-010-01 for Unit 1 dated November 23, 1988 and January 17, 1989, respectively.

Aool 8920030141 DR 890922 ADOCK 05000266 I PNU

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..'. o NRC Document Control Room Page 2 September 22, 1989 l

l An investigation team was formed after the incident to investigate why it happened, determine root causes, and to make recommendations to prevent recurrence. The recommendations were previously presented to you in the "Cortective Actions" section of LER 88-010-01. Section 15.3.7 of the Technical l Specifications, " Auxiliary Electrical Systems", specifies LCO's L for the on-site electrical distribution system. This change L request focuses on identified weaknesses in this section which contributed to the incident.

Each of the two nuclear units at Point Beach Nuclear Plant has two 480 volt AC safeguards buses associated with it, 1(2)-E03 and 1(2)-B04. These buses are supplied, through step-down transformers, with both normal'and emergency power from buses 1(2)-A05 and 1-(2)-A06, respectively.. A05 and A06 are the 4160 volt AC safeguards buses. These buses are normally supplied power from 1(2)-A03 and 1(2)-A04, respectively; but under circumstances which call for diese1' generator activation, these become the buses which receive power from the diesel generators, G01 supplying 1(2)-A05 and G02 supplying 1(2)-A06.

B03 and B04 have a common, normally open, tie breaker, as do A05 and A06.

A problem identified in TS Section 15.3.7 is that no LCO's exist for the case when the bus tie breaker between B03 and B04 is closed. (Electrical interlocks prevent the B03-B04 tie breaker from being closed when the normal supply breaker from either A05 or A06 to either bus B03 or B04 is open.) The shutting of this tie breaker is, in essence, a relaxation of the single-failure criterion, as during this time a bus normally supplied by one train of power is being supplied by the other train of power. This situation is equally applicable to a unit which is critical or a unit which is shut down. The safeguards buses for a shutdown unit are relied upon to supply power to certain vital loads which would be necessary in the case of an accident in the critical unit.

Our review of Revision 4 of NUREG-0452, Standard Technical Specifications for Westinghouse Pressurized Water Fectors (STS), provided some guidance regarding LCO's for safeguards buses. The STS require an independent lineup of the safeguards buses, specifically stating that all tie breakers (between I

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NRC Document Control Desk Page 3 September 22,'1989 redundant buses within the unit and between units at the same station)-are open. Operability of the buses is based on maintaining at least one train of on-site AC' power sources and associated distribution systems operable during accident conditions coincident with an assumed loss of off-site power and single failure of the other:on-site AC source. LCO's in the STS allow deviation from this lineup for up to eight hours,

.or be in at least HOT STANDBY (K e <0.99, T -

withinthenextsixhoursandinbbLDSHUTDOhN9(2350 Keffdegrees

<0.99, F).

T avg $200 degrees F) within the following thirty hours..

We have adopted a similar approach to LCO's regarding bus independence in our proposed changes. TS Section 15.3.7 is essentially split into three sections. Section A.1 addresses necessary conditions to allow bringing one or both reactors critical. Section A.2 addresses prerequisites for abnormal condition start-up of one reactor. Section B.1 addresses LCO's during power operation of-one or both reactors.

We are proposing new TS 15.3.7.B.1.e and TS 15.3.7.B.1.f to address the operability of safeguards buses B03 and B04, and A05 and A06, respectively, during periods when one or both reactors are critical, allowing bus inoperability (which occurs

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when a tie breaker is closed) for up to-eight hours, beyond-which transition to hot shutdown must occur within the.

following six hours, and transition to cold shutdown must occur within the following thirty hours. In conjunction with these new specifications, we are modifying present TS.15.3.7.B.1.e (new TS 15.3.7.1.g) to state that the LCO for diesel generator inoperability may not be applied during the condition when '

safeguards buses are connected through their common tie breaker.

Additionally, we are proposing. modifications to TS 15.3.7.A.1.c and TS 15.3.7.A.l.d ;hich address the condition of safeguards bus tie breakers prior to making a reactor critical. Those specifications will now specify that all safeguards buses in the electrical system shall be in a normal lineup (all tie breakers shall be open prior to making one or both reactors l critical). This ensures an independent and redundant safeguards bus lineup prior to a unit start-up.

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NRC Document Control Room Page 4 September 22, 1989 A similar change is proposed to TS 15.3.7.A.2.d and TS 15.3.7.A.2.e for the abnormal condition start-up of one reactor. The proposed change is essentially identical to the above-described changes to Section A.l.

As required by 10 CFR 50.91(a), we have evaluated this proposed change in accordance with the standards specified in 10 CFR 50.92 to determine if the proposed change constitutes a significant hazards consideration. A proposed license amendment involves no significant hazards consideration if operation of the facility in accordance with the proposed 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, or (3) involve a significant reduction in a margin of safety. Based on the following evaluation, we have concluded that this proposed change will not constitute a significant hazards consideration.

1. Probability or Consequences of Previously Evaluated Accident The proposed changes which add LCO's regarding bus tie breaker operation and safeguards bus operability are new and will impose more restrictive administrative constraints on the electrical distribution system. The probability or consequences of a previously evaluated accident is not increased because the proposed changes do not cause any changes in the physical operation of the plant (except, perhaps, to mandate a unit shutdown where previously a shutdown would not have been required).

2. Possibility of a New or Different Kind of Accident The suggested changes which add LCo's regarding bus tie breaker operations and safeguards bus operability propose no physical modification to the plant, nor do they specify any change in plant operation (other than to stipulate plant shutdown when the single-failure criterion has been relaxed beyond a proscribed amount of time).

Consequently, there is no possibility of creating a new or different kind of accident from any accident previously evaluated.

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NRC Document Control Room Page 5 September 22, 1989

3. Significant Reduction in Margin of Safety The proposed changes adding LCO's regarding bus tie breaker operation and safeguards bus operability have been included in order to limit the amount of time the single-failure criterion is relaxed. No limit previously existed in this regard in these Technical Specifications.

l Therefore, the addition of these new restrictions, the l result of which is the requirement for plant shutdown when l a short time period is exceeded, can only be seen as an increase in margin of safety.

Please contact us should you have any questions regarding this submittal.

Very truly yours, hO $l C. W. Fay Vice President Nuclear Power Attachments Copies to NRC Regional Administrator, Region III NRC Resident Inspector R. S. Cullen, PSCW Subscribep and sworn to before me this 23 L day of Lg d e , 1989.

Notary Public, State of Wisconsin My Commission expires [-27-90

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