ML20099G072

Requests Regional Temporary Waiver of Compliance from TS LCO for Inoperability of Safety Injection Accumulator D,Per 920806 Telcon W/Nrc.Accumulator Discovered Leaking on 920701.Replacement Requires Depressurization of Accumulator

ML20099G072
Person / Time
Site:	Callaway
Issue date:	08/06/1992
From:	Blosser J UNION ELECTRIC CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20099G068	List: ML20099G072
References
ULNRC-2679, NUDOCS 9208140088
Download: ML20099G072 (6)

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X August 6 1992 3

Mr. A. Bert Davis Regional Administrator, Region III U. S. Nuclear Regulatory Commissic.n 799 Roosevelt Road Glen Ellyn, Illinois 60137 ULNRC 2679

Dear Mr. Davis:

DOCKE1 NUMBER 50-483 CALLAWAY PLANT UNIT 1 REQUEST F0lt REGIONAL TEMPORARY

}{Aly_ty, OF COMPLI A_N,CJ This letter is to confirm the resalts of a teleconference between Union Electric and the NRC Region III 5;aff on August 6, 1992, in which Union Electric requestod a Regional Waiver of Compliance from 0600 CDT August 7 1992, until 0600 CDT August 8, 1992, from the Technical Specification Limiting Conditions of Operation (LCO) for the inoperability of a Safety Injection accumulator. This vould allow completion of repairs to tho

• D' Ecergency Core Cooling Safety Inj ection accumulator vent valve. Currently, Callaway Plant is in Mode 1. 100 percent power, The basis for this request is provideo below:

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fACKQROUND On July 1, 1992, at 0800 CDT, thi

'D' Safety Inj ection accumulator vent valve. EP.HV.8950r, was discover d leaking nitror,an. The licensed operators observed the leak after noticin6 the accuculator had to be repressurized on a daily basis. Durin5 a centainment entry, the valve seat Icak rate was quantified at 1 liter per second s'

R1001REMENTS POR VHICH Tile VAIVEk_IS REOUESTED 8

Replacement of valvo EP.Hv.6950F requires

'D' Safety Injection acewnulator l

o ha depressurized. The Technice.1 Specification (T/S) 3.5.1.d Limiting Condition for Operation (LCO) would not be satisfied with nitrogen cover pressure of less than 602 psig.

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Page 2 ULNRC.2679 k*ith this

'D' Safety Injection ac, umulator dopressurized, the Technical Specification LCO action statement allows 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to restore the accumulator operable or shut down to Hot Standby (Mode 3) within thw next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and reduce Reactor Coolant System (RCS) pressure to less than 1000 psig within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. This vaiver request would extend the allowabic outage time for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to coeplete the maintenance and necessary tests of the

'D' Safety injection accuculator.

CIRCtHSTANCES/NEED TOR PROMPT ACTIONNdY SITUATION COULD NOT HAVE BEEN AVOIDED Extencien of the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> allowed outage time limit is needed to permit valve replacement and avoid a cooldovn transient that vould be imposed upon the plant by an unnecessary shutdown to Mode 3 conditions, Since the onset of valve EP HV 6950T leakage could not have been reasonably predicted, this situation could not have been avoided. Prompt action is needed to eliminate the need for frequent operator action to maintain the accumulator pressure within the Technical Specification limits and reduce unnecessary cycling of other plant comptnents.

COMPENSATORY ACTIONS During the cine frcme this valver of compliance would be in effect, the following conpensatory actions will be taken:

Procedura OTS EP 00005, the governin6 proceduro to control replacement of valve EP HV 8950F, has been written and approved to provide actions for the licensed operators in the event accumulator icvel or pressure begins to decrease on one of the other three safety _ Inj ection accumulators.

Additionally, the pro job brief w'.11 strast the importance of increased conitoring of pressure in the three operable accuauintors. Potential leakage throu5h the accumulator discharge check valve, E? 89563, will be closely monitored and appropriate Technical Specif t. cation oction statements for check valve leakage vill be in11cwed including plant shutdcur if required.

S AFETY. SIGNTFICMCE ANDETENTI AI. CohSEQUEEGES OF PROPOSED REO'LE.SJ This in a one time request for approval of an allowed outage time of 24 hcura with one Safety injection Accu:ulator inoperable. This request would extend the existing Technical Specification allowed outage time by 23 hours2.662037e-4 days <br />0.00639 hours <br />3.80291e-5 weeks <br />8.7515e-6 months <br /> I

to parait completion of the maintenance and necessary tddes to the 'D' Safety Injection accumulator. Additional discussionc regarding safety significance are presented below in the Hazards Consideration.

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4 Page 3 ULNRC 2679 9

DJ2FATTnN JUSIIFICAILQ2 -

1 1he proposed waiver of compliance is for a one-time approval of plant operation for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with one Safety Injection acewtulator j

inoperable for maintenance. The auditional tima vill provide sufficient time to replace the valve and restore the

'D' safety injection accumulator to operable status. If the accumulator is not restored within the extendad allowable outage time we will comply with the Technical Specificction LCO to shut down the plant to Hot Standby within the next 6 houra and reduen RCS pressure to less than 1000 pelg within the followin6 6 houra.

BASIS FOR' NO SIGNIFICANT HAZARDS CONSIDffATION Union. Electric has coneleded that the requested temporary waiver of compliance does not involve a significant hazard in that it would not:

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Involve a significant increase in the probability or consequences of any accident previously evaluated.

This change involves exterding the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> LCO action allowed outage tiee to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with an inoperable Safety inj ect. ton cecumulator.

As such, this change does not. increase the probability of any accident previously analyned.

One Safety Injection accunulator, in conjunction with other ECCS systems, is capabic of mitigating the Design Bania Accidente (DBAs). If a single failure is not postulated, consequences of the DBAs are not adversely afrected (i.e., the requirements of 10CTR50,46 are mat). The ffect on the consequences of an accident, assuming a single failure would be no different for the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period than the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> pe.'iod as currently allowed, Znus. the consequences of eccidents are not adversely impac:cd by the proposec waiver of compli..nce.

2, Creata the possibility of e new or different kind of accident.

Any previously analyzed e ent postulated during the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> extension period can be r> tigated by the remaining components of thn Ecos including the ot:"er three safety Injection accumulacora if to _ ingle failure is postalated.

Since the proposed vaivar vould allow plant operation for an additional 23 hours2.662037e-4 days <br />0.00639 hours <br />3.80291e-5 weeks <br />8.7515e-6 months <br /> with nne Safety Injection accumulator inoperable, the change vcolo increase slightiy eMe probability of failure of the subsystem should it be required to operate to mitigata a DBA. The probability of core damage risk has been calculated for Callaw.sy to increase by only 0.01 percent above the value determined for the rallaway Plant's Individual Plant Examination.

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Dage L ULNRC.2679 it should be noted that t ua rnodel used to siculato removal of one accunulator from service assumed that the Residual Heat Recoval and Safety Injection punp diuharge paths to the

'B' RCS loop vere also rendered inoperable. This slight increase in risk is not de err ed lar6e enough to verrant consideration as a new or different kind of accident.

3.

Involve a significant re6uction in any nargin of safety.

As discussed above, the consequences of any DhA are not advert,ely affected if no single failures are.sssumed. With a single failure, the consequences and input on margin of safety are no different during the LCO 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> allowed outaae time than for the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> allowed outage time; the only difference is in the period of tinte allowed. This small increase in rish (0.01 percent) does not result in a significant teduction in any margin of safety.

Mill.J_QL,ftQ R.5IyD11hLE ENy1RQN!GNTAL_CGijE00ENCFS The proposed temporary vaiver of compliance to continue power operatica for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with one Safety injectir n accuculator inoperable to perforet the correctivo re.nintenance has n, environmental 1rpact, b2?D1 The Callavay Plant On Site Revieu Committaa has approved this request for a tettporary vaiver of compliance ar d concurs with the above determinations.

7nis proposed reg, r a temp,.rary valver involves no unuue safe ty risk

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not irreversible er.

.nmental c-nsequences.

':o vill continue to keep you inf. read on matters relevant to thic requnst.

Very truly yours, 4.4fu/

'J. D. 31osser Managet, Callavcy T'.anc JDB/TPS/Irj j

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distribution attached

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Mr. L. Raynard Vharton (2 copica)

U, 5, Nuclear Regulatory Commisstia OVfN Mail Stop 13E21 Vashington, D. C.

20555 Managt.

Electric Deparecent Misat.-

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.60 Jefferson City MO 65102 Recorde Center Institute of Nuclear Power opora::ons Suite 1500

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1100 Circle 73 Parkway Atlanta, GA 30339 Mr. Steve Vicecan Supervisor, Licenalng Volf Creek Nuclear Operating Corpration P. O. Box 411 Larlington, KS 66839 Mr R, L.',aaue Chief. Projnx Section 3C U. S. Nucicar Regulatory Comn:Issi:.a Region III 799 Roosevelt Road i

Clen Ellyn, IL 50137 KRC Senior Resident..:pector

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