ML20087A113

Application for Exigent Amend to License DPR-53,providing Relief from TS 4.5.1 & Requesting Temporary Relief from Compliance from Subj Requirement During NRC Review of Amend Request

ML20087A113
Person / Time
Site:	Calvert Cliffs
Issue date:	12/31/1991
From:	Creel G BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20087A116	List: ML20087A113 ML20087A118
References
NUDOCS 9201080194
Download: ML20087A113 (7)

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A B ALTIMORE GAS AND ELECTRIC 1650 CALVERT CUFFS PARKWAY LUSBY, MARYLAND 20657 4702 GEORGE C. CREEL wer PassiocNT Nucttan ENEROY am ao..n December 31,1991 U. S. Nuclear Regulatory Commission Washington, DC 20555 NITENTION:

Documeat Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit No.1; Docket No. 50-317 Request for Exigent License Amendment and Temporary Waiver of

. Compliance: Verification of Safety Iniection Tank Isolation Vake Position Gentlemen:

The Baltimore Gas and Electric Company (BG&E) hereby requests an exigent license amendment to provide relief from a requirement of Calvert Cliffs Unit No.1 Technical Specification 4.5.1. We also request that the NRC grant a temporary waiver of compliance from the same requirement while this amendment request undergoes NRC Staff review. Baltimore Gas and Electric Company has considered possible alternatives to this request and we have determined that the approach described below represents the safest course of action.

I.

REOUEST FOR AMENDMENT DESCRIPTION Technical Specification 3.5.1, Safety Injection Tanks, requires each of the four safety injection tanks (SITS) to be operable during Modes 1,2, and 3 by maintaining the four SIT isolation valves open and de-energized, and by keeping various SIT parameters within specified ranges. The isolation valves are maintained opened and de-energized during power operation to protect against 15cir inadvertent closure and possible interference with the safety function of the SITS.

Technical Specification Surveillance Requirement 4.5.1.a.2 requires that each SIT isolation valve be verified in the open position at least once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This requirement is normally satisfied by viewing a control room indication of valve position. For the reasons described below, however, this remote position indication has been disabled for one of the four SIT isolation valves (MOV-644) as part of a modilication that mechanically secures that valve in the open position. This modification was implemented aft;r the valve stem for MOV-644 was discwcred to be bent. The modification, which entailed welding the valve stem to the valve yoke, was necessitated by the removal of a portion of the MOV assembly. This in turn disabled the valve position indicator.

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December 31,1991 j

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. The proposed change to the Surveillance Requirement would remove the requirement to verify the position of MOV-644 at least every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. We request that this change be effective until the next L

scheduled refueling outage, at which time repairs will be effected to restore the valve operator to its j

normal configuration. We believe that welding the valve in the open position climinates the need to l

periodically verify that the valve is open. All other surveillance requirements of Specification 4.5.1 will continue to be satisfied at the required frequency, i

4 l-IIACKGROUND t

i On December 22,1991, Unit I was shut down r.nd placed in Mode 4 to c(mduct repairs to a leaking j'

check valve (SI-245) located downstream of SIT 12B. In support of this repair, SIT isolation valve l

j' MOV-644 was ckised to isolate SI-245 from the Reactor Coolant System (RCS). Following repairs i

on SI-245, the plant operators attempted to reopen MOV-644 to conduct post-maintenance testing 4

i-and return SIT 12B to service. However, MOV-644 failed to open. Following an inspection of the i

valve it was determined that the valve stem was bent, causing binding in the motor-operator. The j

cause of the bent stem has not been conGrmed at this time but it is suspected to have occurred when excessive force was used to manually close MOV-644 for the repair of SI 245, 1

To allow MOV-644 to be opened, the stem nut had to be removed from the motor-operator. Thi-j provided sufGeient clearance to allow the bent stem to travel into the motor-operator housing.

i However, the stem nut is the means by which the motor-operator grasps the valve stem and its i

removal left the valve stem unsecured. Consequently, we have modified the valve by performing a j

360" weld around the unthreaded portion of the valve stem to the valve yoke to positively maintain the valve in its open position. The initial weld design calculation resulted in a 40% design margin. A

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i detailed weld design calculation was performed incorporating more explicit modelling of deadweight, i

thermal, scismic, and packing loads. This calculation demonstrated that the margin between actual l'

and allowable weld loads was approximately 22%. The weld was performed using existing weld i

procedures followed by dye penetrant and visual inspections. This work was completed on j'

December 28. Th weld was also visually inspec'ed after reaching normal operating conditions on December 30.

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.We have assured ourselves that the valve is in the open position throul.h several indications.1) A i

test was performed on the repaired check valve that required passing water from the SIT, through the check valve and the isolation valve into a drain line. We received positive indication of Gow through the valves (i.e., _ SIT level decreased) which indicated ths

• ie isolation valve is open.

2) When we opened the isolation valve, the expected amot.nt of stem travel was measured. 3) Once the stem nut was moved past the binding portion of the stem,it moved freely. This indicates that the E

damage was localized to a particular region of the stem. 4) According te the weak link analysis, the

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stem is the most likely location for failure. The next location of predicted failure is the bottom of the j

wedge at the valve seating surface. However, no seat leakage was observed while repairing the j'

downstream check valve. This indicates that the damage was localized to the valve stem. 5) When f

the valve was opened, both with the hand wheel and with a portable rigging device, the force required to move the valv. we similar to what would be expected of a properly operating valve.

These indications lead ~us to conclude that the valve is in its open position, e

1-Another consequence of removing the stem nut from MOV-644's-motor-operator was that it disabled the valve's stem position indicator. We use this indicator to comply with Surveillance Requirement 4.5.1.a.2, which specifies that the valve position must be verified as open at least once l

every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This change is requested because BG&E beliews it to be unnecessary to verify the position of MOV-644 every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> as the valve is now welded in the open position.

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Document Control Desk

. December 31,1991 Page 3 REOUESTED CilANGE Change Snecification 4.5.1.a.2 of the Unit i Technical Specu stions as shown on the markcJ.up page attac..ed to this submittal. This change exempts SIT olation valve htOV-644 from the requirement to verify the open position of the SlT isolation valves. This change is requested to be effective until the end of the next refueling outage currently scheduled for the spring of 1992.

SAFIM ANALYSIS / JUSTIFICATION There are four Safety Injection Tanks installed on Calvert Cliffs Unit No.1. One tank is connected to each cold leg by 12-inch diameter piping. The safety injection system is designed as a passive system to provide borated water to cover the core following a loss of Cool.mt Accident (LOCA) until the s-fety injection pumps can provide adequate water for core cooling. The driving force for the SIT water injection is provided by a nitrogen gas overpressure. In order to prevent the RCS from -

mixing with, and possibly diluting the borated SIT water, two check valves surrounding a motor-operated isolation valve are located between each SIT and the RCS. During Modes 1,2, and 3, the isolation valve is required to be open. The isolation valve is normally locked open with a keylock switch and power is removed from the motor-operator in accordance with Technical Specification 4.5.1.c. In the event of a.LOCA, the check valves would open when RCS pressure decreases below the SIT pressure and the SIT water would inject into the RCS. The SIT isolation valve is closed to isolate the SIT during normal RCS depressurization to prevent the tank water from discharging into the RCS. Since MOV-644 is welded open, we will vent SIT 12f3 when depressurizing the RCS to prevent it from discharging. All procedure changes needed to operate with MOV-644 welded open have been approved.

The purpose of Surveillance Requirement 4.5.1.a.2 is to periodically ensure that the isolation valves remain open and thus, would not prevent the SITS from performing their safety function.

Compliance with Surveillance Requirement 4.5.1.a.2 is currently being met by making a containment entry at least once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to visually verify the valve position. Whereas this is a practical means for compliance during Modes 2 and 3, this will not be desirable during Mode 1 due to elevated

' radiation levels inside containment during power operation. Therefore, continued plant operation using direct visual inspection as the mer is for satisfying the surveillance requirement is not cocsistent with the objectives of maintaining occupation radiation exposures as low as reasonably achievable (ALARA).

Installation of an alternate means of verifying valve position, such as a video camera or an electrical contact,were considered. Installation of an alternate position indication would require that the plant be shutdown, or, if installed at power, additional radiation exposure be accumulated in opposition to ALARA practices. These alternatives were rejected because providing an alternate means of position indication on a welded open valve is unnecessary and yields no safety benefit.

Another alternative considered was to perform a full repair of MOV-644 prior to returning to power.

Repair of this valve necessitates opening the RCS and would therefore require that the plant either be placed in Mode 5 (Cold Shutdown) with a partially drained RCS, or that a freeze seal (if possible) be installed in the 12-inch SIT line, it is estimated that it would take approximately seven days to

- perform this repair. This was not considered to be an acceptable alternative because it would impose an unnecessary economic hardship on BG&E by preventing the plant from returning to power operation while providing no corresponding safety benefit. There is no discernible safety benellt in

Document Control Desk

, December 31,1991 Page 4 repairing the valve at this time because the valve has been secured in the position required by technical specifications for power operation; Verifying the position of a welded open vahc is unnecessary. More importantly; BO&E desires to avoid any_ unnecessary entry into a partially drained RCS condition, due to the increased plant vulnerability to unexpected transients while in thh condition.

DJ TERMINATION OF SIGNIFICANT llA7ARI)S J

The proposed change has been evaluated against the standards in 10 CFR 50.92 and_ has been determined to not involve-a significant hazards consideration, in that operation of the facility in accordance with the proposed amendment:

1.

Would not involve a significant increase in the probabdity or consequences of an accident previously evaluated.

The open or closed position of Safety injection Tank isolation valves are no; considered an initiator for any accidents previously evaluated. Therefore, the probability of previoufy evaluated accidents would not be increased by the requested change.

. Previously evaluated accident analyses assume that Safety Injection Tank isolation valves are open. The requested change climinates the verification of that condition for one valve but the valve has been welded in the open position. Therefore, it has been assured that the valve will function as required during any previously analyzed accident and that there will be no increase in consequences due to the requested change.

.Therefore, this change would not involve a significant increase in the probability or consequences of an accident previously evaluated.

2.

Would not create the possibility of a new or different type G accident from any accident previously evaluated.

Welding the valve stem to the valve yoke on MOV-644 ensures that the valve will remain open during Modes 1,2 and 3, thus climinating the need for periodic verification of valve position in those Modes. The only new or different type of accident that could be created by failing _to verify the isolation valve position would be the unknown closure of the valve.

Ilowever, this possibility is precluded by welding the valve in the open position. This change in surveillance requirements does not affect the design or function c the isolation valve, nor r

the operation of the isolation valve m b valve's design and funt n is to remain open in Modes 1,2,3 and the valve is not allowe.' t be operated in thosc Mt s.

Therefore, the proposed change does a create the possibility of a new or different type of F

accident from any accident previously evaluated.

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Would not involve a sigraficant reduction in a margin ofsafety, The margin of safety provided by this surveillance requirement is the assurance that the isolation valve is open. The need to verify that the valve is open has been climinated by l

• Document Control Desk

. December.11, lW1 Page 5 weldmg the valve in the open position. Therefore, the proposed change would not involve a significant reduction in a margm of safety.

STA'i EMIEF OF ITLGENT.CIRCliMNTANCES The Technical S ccifications, unless arnended, would require entry into containmer.t at power by an

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operator to veri'y the pmition of the welded open valve. 'thh will result in the accumulation of unnecessary radiation espost.re with no cort aponding safety benefit. Therefore, we request that this amendment be treated as t.a exigent change.

The need for this change ould not have been foreseen in that it resulted frorn corrective maintenance.:tivities being performed during an unplanned outage to repair a leaking check valve.

Application ior an amendment was made as soon as possible following the determination of the appropriate course of action.

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LtEOUENT I OR _TEMPORAlW WAllyR OF CQMl'l,MNG 11altimore Gas and lilectric Company requests that the NRC waive the requirement to comply with Surveillance Requirement 4.5.1.a.2 for MOV.644 while the exigeat license amendment is considered.

'the circumstances resuaing in the loss of controlioom indication of MOV 644 have been described above and currently, compliance with the Surveill.mee Requirement is being met by containment i

entries to perform a visual verification of valve position, llecause of the radiation levels in the containment during power operation, roatinuance of this practice is undesirable.

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'lhe need for this change could not have been foreseen in that it resulted from corrective maintenance activities be:ng perfor med during an unplanned outage to repair a leaking check vr.c.'e.

The safety significarice of this requested waiver is the same as the safety significance of the icquested license amendment. We believe that welding MOV454 in the open position provides the same level of safety as verifying the position of the valve at least every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. As discussed in the

" Determination of Significant llazards," above, this change does not constitute an unreviewed safety hazard.

COMPENSATOlW ACll&NS For the period of titt mis temporary waiver is in effect,..ssurance of safety is provided by the weld on MOV-644. Ily p.

mding any valve stem movement, this measure adequately compensates for the lack of periodic po.non veiification.

UtilWQON OF Riiqt1EST The temporary waiver of compliance is requested while the exigent License Amendment Request undergoes NRC Staff review. This will allow us to discontinue the containment entries currently being made to visually satisfy Surveillance Requirement 4.5.1.a.2.

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4 Dorv uent Control Desk December 31,1991 page 6 120MONMENTAl, CONSEQl'JiNCl2i This sequest, if granted, would not intohe an increase in the amount or types of c(lluents that inay be released off site, nor will there be any increase in individual or cumulative occupational radiation exposure. llowever, the approval of this request would decicase occupational radiation esposure.

Therefore, this tequest would not involve irre /crsible environmental consequences.

Sif171Y COMMflTEE 11EYll;_W The proposed license amendment and our determination of r,ignificant hatards have i 1 reviewed by our Plant Operations and Safety iteview Conunittee and Off Site Safety lleview '

cittee, and the request for a temporary waiver of compliance has been reviewed by our Plant O[ rations and Safety lleview Committee. They have concluded thr.t implementation of these changes wP.I not result in an undue risk to the health and safety of the putilie.

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Very truly yours,,[

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, Ped, be{ ore nc, the bscriber, a Notary Public of the State of htaryland in and for

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's. t n personally v>peared George C. Creel, being duty sworn, and states that he is Vice Presideht of the Baltimore Gas and Electric Company, a corporation of the State of hiaryland; that he provides the foregoing information for th; purposes therein set forth; that the staternents made are true and correct to the best of his knowledge, information, and belief; and that he was authoriecd to provide the information on behalf of said Corpo:ntion.

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Date GCC/BDhi/DJhildjm! dim Attachment

Document Control Desk

. Decemter 31,1991 i

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D. A !! rune, Esquire J. E. Silberg, Esquire R. A Capra,NRC D 0, hicDonakl.Jr., NRC T, T. Martin, NRC L E. Nicholson. NRC 1

R.1. Mclean, DNR J.11. Walter, PSC l

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