ML17326A072

Forwards LER 99-018-00 Re Refueling Water Storage Tank Suction Motor Operated Valves Inoperable,Due to Inadequate Design.Listed Commitments Were Identified in LER

ML17326A072
Person / Time
Site:	Cook
Issue date:	07/29/1999
From:	Rencheck M INDIANA MICHIGAN POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17326A073	List: ML17326A072 ML17326A074
References
NUDOCS 9908060199
Download: ML17326A072 (8)

Text

~ CATEGORY Q REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9908060199 DOC.DATE! 99/07/29 NOTARIZED: NO DOCKET FACIL:50-315 Donald C. Cook Nuclear Power Plant, Unit 1, Indiana M 05000315 A~).. NAME AUTHOR AFFILIATION RENCHECK,M.W. Indiana Michigan Power Co. (formerly Indiana 8 Michigan Ele.

RECIP.NAME RECIPIENT AFFILIATION Records Management Branch (Document Control Desk)

SUBJECT:

Forwards LER 99-018-00 re refueling water storage tank suction motor operated valves inoperable,due to inadecpxate design. Listed commitments were identified in LER.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR I ENCL I SIZE: 7 TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES: E RECIPIENT COPIES RECIPIENT COPIES ZD CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL LPD3- 1 1 STANG,J 1 1 0 INTERN LE C NRR/DRIP/REXB 1,1 1 1 NRR/DIPM/IOLB NRR/DSSA/SPLB 1

1 1

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RES/DET/ERAB 1. 1 RES/DRAA/OERAB 1 1 RGN3 FILE Ol 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LMZTCO MARSHALL 1 1 NOAC POORE,W. 1 1 NOAC QUEENER, DS 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1

'

D NOTE TO ALL "RZDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DZSTRIBUTION LISTS OR REDUCE THE NUMBER OF COPZES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 15 ENCL 15

indiana Micht Power Company Cook Nudoat Rant One Cook Rata MI49106 616 465 5901 Z

INDIANA NICHIOiAN POWER July 29, 1999 United States Nuclear Regulatory Commission Document Control Desk DC 20555 'ashington, Operating License DPR-58 Docket No. 50-315 Document Control Manager:

In accordance with the criteria established by 10 CFR 50.73 entitled Ucensee Event Re ort S stem the following report is being submitted:

LER 315/99-018-00, "Refueling Water Storage Tank Suction Motor Operated ~

Valves Inoperable Due to Inadequate Design".

The following commitments were identified in this LER.

~ A permanent modification will be made to the RWST to CCP suction MOVs for both Units to replace the valve yokes with different yokes capable of withstanding the combined loads associated with actuator closure and a seismic event prior to Mode 4

~ Necessary corrective actions or analyses to establish operability for safety-related Limitorque MOVs in Modes 1P will be performed prior to entering Mode 4.

Sincerely, Vice President Nuclear Engineering

/Irb Attachment c: J. E. Dyer, Region III R. P. Powers P. A. Barrett G. P. Arent

'P'tt080b0i99 990729 PDR ADOCK 05000315 S PDR

R. 'hale D. Hahn Records Center, INPO NRC Resident Inspector

NRC FORM 366 U.S. NUCLEAR REG ORY COMMISSION APPRO BY OMB NO. 3150-0104 EXPIRES 06/30/2001 Estimated burden per response to comply with this andstory Informatbn LICENSEE EVENT REPORT (LER) cogection request: 50 hrs. Reported lessons learned are I corporated Into the licensing process and fed back to Industry. Forward comments regarding burden estimate to the Records Management Branch (TA F33), U.S. Nudear Regubtory (See reverse for required number of Comndsskrrl Washingtofl DC 205550001. and to the Paperwork Reductkrn digits/characters for each block) Project (3I500t04), 05ce of Management and Budget, Washington. DC 20503.

If an information codection does not display a cunently veld OMB control Aurnbef. Ihe NRC may Aot coAduct of spoAsof, aAd a persoA Is Aot fegulfed to respond to, the information olectiorl FACIUTY NAME (tl DOCKET NUMBER l2) PAGE (3)

Cook Nuclear Plant Unit 1 05000-315 1 OF 4 TITlE tel Refueling Water Storage Tank Suction Motor Operated Valves Inoperable Due to Inadequate Design EVENT DATE (5) LER NUMBER (6) REPORT DATE l7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR SEQUENTIAL REVISION MON1H DAY YEAR FACLIIYNAME DOCKET NUMBER NUMBER NUMBER Cook Nuclear Plant Unit 2 05000-316 1999 FACUIYNAME OPERATINQ THIS REPORT IS SUBMmED PURSUANT TO THE REQUIREMENTS OF '10 CFR E: (Check one or more) (11)

MODE (9) 20.2201(b) 20.2203{a)(2)(v) 50.73(a) (2) (i) 50.73(a)(2)(viii)

POWER 20.2203{0) {1) 20.2203(a) {3)(i) X 50.73(a) {2){ii) 50.73(a)(2)(x)

LEVEL {10) 20.2203{a)(2)(i) 20.2203(a)(3)(ii) 50.73(a) {2Hm) 73.71 20.2203(a) (2)(ii) 20.2203{a)(4) 50.73{a) {2)(iv) OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50.73{a){2)(v) Specify in Abstract below or in NRC Form 366A 20.2203(a)(2)(iv) 50. 36(c) (2) 50.73{a) (2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TElEPHONE NUMBER tindude Area Code)

Lyle R. Berry, Regulatory Compliance Engineer (616) 465-5901 X1 623 COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TO EPIX TO EPIX III'Il080b02 g7 990729 PDR ADQCK 050003%5 S PDR SUPPLEMENTAL REPORT EXPECTED 14 DAY YEAR X YEs NO 12 31 1999 (If yos, complete EXPECTED SUBMISSION DATE).

ABSTRACT (Umit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On June 29,1999, during a review of a stress calculation for the Refueling Water Storage Tank (RWS f) motor-operated (MOV) suction valves to the centrifugal charging pumps (CCPs), it was determined that the valve yokes may yield under the combined stress of a seismic event and the static, valve closed, stem thrust. Based upon discussions with Engineering personnel, Operations declared the MOVs inoperable at 1540 hours0.0178 days <br />0.428 hours <br />0.00255 weeks <br />5.8597e-4 months <br />, June 29,1999. Since these MOVs were considered to be incapable of opening during a postulated seismic event, this condition is reportable pursuant to the requirements of 10CFR50.73(a)(2)(ii) as an event that resulted in the nuclear power plant being in a condition that was outside the design basis of the plant. Technical Specifications (TS) require one boron injection path from the RWST to the Reactor Coolant System (RCS) to be operable in Modes 5-6 and two boron injection flow paths in Modes 1-4. Since these valves were determined to be inoperable in those modes, this condition is also reportable pursuant to the requirements of 10CFR50.73(a)(2)(i) as an operation or condition prohibited by TS. The apparent cause for this event was inadequate design of the MOVs. This event is applicable to both Units. Compensatory action for the RWST to CCP MOVs for both Units has been taken via a temporary modification to restore operability in anticipation of changing from Mode 5 to Mode 6 to allow removal of fuel from the vessel. Evaluation of the extent of this condition has identified that a change in the method of calculating torque/thrust available from the actuator, initiated by Limitorque Technical Update 98-01, may also impact the operability of the RWST to CCP suction MOVs and other Limitorque MOVs. Operability determinations were performed for those valves required for core offload and reload to establish operability in Modes 5 and 6. Necessary corrective actions or analyses to establish operability for safety-related Limitolque MOVs in Modes 1-4 will be performed prior to entering Mode 4.

Based upon the proceduralized capability to establish an ECCS boration flowpath, should the RWST to CCP suction MOVs fail to open on demand, this event had minimal impact on the health and safety of the public.

RG 0 M366{6-1998)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-19981 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACIUTY NAME (1) DOCKET (2) LER NUMBER (6) PAGE (3)

Cook Nuclear Plant Unit 1 05000-315 SEQUENTIAL NUMBER REVISION 2 OF 4 NUMBER 1999 018 00 TEXT /ifmore specois required, use edditionei copies of NRC Form 366A/ (17)

Conditions Prior To Event Unit 1 was in Mode 5, Cold Shutdown Unit 2 was in Mode 5, Cold Shutdown Descri tion Of The Event On June 29,1999, during a review of a stress calculation for the Refueling Water Storage Tank (RWST) motor-operated (MOV) suction isolation valves (BQ/ISV) to the centrifugal charging pumps (CCPs), it was determined that the valve yokes may yield under the combined stress of a seismic event and the static, valve dosed, stem thrust. A preliminary MOV weak-link calculation for 2-IMO-910 and 2-IMO-911 was performed by Altran Corporation to include stem thrust as an additional load on the valve yoke, since this had not been addressed in previous calculations. These calculations indicate the valves cannot be considered operable if the MOVs are closed with seating thrusts exceeding designated dosing thrust values. The Altran analyses indicate the electrically closed valves may not successfully maintain valve yoke structural integrity during a seismic event. Based upon discussions with Engineering personnel, the Operations Shift Manager declared the MOVs inoperable at 1540 hours0.0178 days <br />0.428 hours <br />0.00255 weeks <br />5.8597e-4 months <br />. This event is applicable to both Units.

Evaluation of the extent of this condition has identified that a change in the method of calculating torque/thrust available from the actuator to open or close Limotorque MOVs, initiated by Limitoique Technical Update 98-01, may also impact the operability of the RWST to CCP suction MOVs and other Limitorque MOVs.

Cause Of The Event The apparent cause of this event was inadequate design of the associated MOVs. A contributing causal factor was the failure of the MOV Program to adequately address industry information for applicability at D.C. Cook. The significance of MOV actuator loads on the seismic capability of MOVs 1/2-IMO-910, and 1/2-IMO-911 in the closed position was not identified and resolved in a timely manner.

Anal sis of the Event Since the RWST to CCP suction MOVs were considered to be incapable of opening during a postulated seismic event, this was determined to be reportable pursuant to the requirements of 10CFR50.73(a)(2)(ii) as an event that resulted in the nuciear power plant being in a condition that was outside the design basis of the plant. Technical Specifications (TS) require one boron injection path from the RWST to the Reactor Coolant System (RCS) to be operable in Modes 5-6 and two boron injection flow paths in Modes 1-4. Since these valves were determined to be inoperable in those modes, this condition is also reportable pursuant to the requirements of 10CFR50.73(a)(2)(i) as an operation or condition prohibited by TS.

The RWST to CCP suction isolation valves are normally closed 8-inch valves arranged in a parallel configuration in the supply piping from the RWST to the charging pump suction header. The safety function of these valves is to open on a Volume Control Tank (VCT) LOW-LOW level signal or on a safety injection signal to provide an ECCS boration flowpath to the RCS. These valves can be remotely opened and dosed during normal and emergency conditions.

From a structural standpoint, the capability of the RWST to CCP suction MOV yokes to withstand simultaneous seismic loading combined with the actuator induced thrust and torque operating loads cannot be shown to meet operability criteria.

NRC FORM 366A (6-1996)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION 16.1999)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACIUTY NAME {1) DOCKET L2) LER NUMBER I6) PAGE I3)

Cook Nuclear Plant Unit 1 05000-315 YEAR sEQUENTIAL NUMBER REVIsioN 3 OF 4 NUMBER 1999 018 00 TEXT /ifmore spaceis required, use additional copies of NRC Form 366AI l17)

This combination of actuator operating loads with seismic loads would occur if a postulated design basis seismic event were to occur with the MOV in a closed position. With the MOV in the open position (but not power back-seated), actuator operating loads are such that the valve yoke structure has the capability to withstand the seismic loading alone. Therefore, if the valve were open during a seismic event, the ability of the valve to dose during or after the event would not be compromised. With the MOV in the closed position (normal operating condition), actuator loads combined with the postulated seismic loads may have prevented opening of the valve in response to a Sl signal resulting in failure to align the CCP to the RWST.

During power operation, CCP suction is supplied from the VCT through the normally open MOVs 1/2-QMO-451 and 1/2-QMO-452. MOVs 1/2-QMO-451 and 1/2-QMO-452 automatically close once RWST to CCP suction MOVs (1/2-IMO-91 0, and 1/2-IMO-911) complete opening. The volume in the VCT is not sufficient to satisfy Sl requirements, nor does it contain sufficient borated water, which is required to control reactivity changes in the Reactor Coolant System (RCS). If the RWST to CCP suction MOVs for each Unit both failed to open upon receipt of a safety-injection (Sl) signal, the normal design flow path for borated water from the RWST to the RCS would not be available.

In the event of a smail break loss of coolant accident (SBLOCA) without Sl, CCP suction from the VCT will be the source of borated makeup. The Emergency Operating Procedures (EOPs) require the operator,to verify at least one CCP is running and control charging flow from the VCT as necessary to maintain pressurizer level.

For a SBLOCA with Sl, or a large break LOCA (LBLOCA), the EOPs require verification that Sl is actuated and that the RWST to CCP suction MOVs open. Plant operator(s) would be dispatched to attempt to manually open the valves if they did not open. The Safety Injection pumps also provide borated water from the RWST to the RCS. If the flowpath from RWST via the charging pumps cannot be manually established, Sl pump flow is verified (or established, if the pumps are not running and/or appropriate valves are not aligned) once the requisite lower RCS pressure of 1630 psig is achieved.

Therefore, regardless of the size of the break, a boration flowpath Can be established. Based upon the proceduralized capability to establish an ECCS boration flowpath, this event had minimal impact on the health and safety of the public.

CORRECTIVE ACTIONS Upon discovery of the identified condition, the RWST to CCP suction MOVs were declared inoperable. A temporary modification was completed to lower the torque/thrust settings for the RWST to CCP suction MOVs on Unit 2 and Unit 1, in anticipation of changing from Mode 5 to Mode 6 to allow removal of fuel from the vessel. These temporary modifications were completed and the boration flowpath from the RWST to RCS declared operable on July 8, 1999 and July 11, 1999, for Unit 2 and Unit 1, respectively. A permanent modification will be made to the RWST to CCP suction MOVs for both Units to replace the valve yokes with different yokes capable of withstanding the combined loads associated with actuator closure and a seismic event prior to Mode 4.

Operability determinations were performed for those valves required for core offloa and reload to establish operability in Modes 5 and 6. Necessary corrective actions or analyses to establish operability for safety-related Limitorque MOVs in Modes 1-4 will be performed prior to entering Mode 4.

This condition was discovered as a part of the programmatic review of safety related MOVs for design, testing, and potential operability concerns in support of the closure of outstanding Generic Letter 89-10 Program issues. This review of the MOV Program is scheduled for completion by December 1, 1999. Resolution of identified deficiencies will be addressed and tracked to completion via the Corrective Action Program. Significant changes to the cause of event, extent of condition, safety significance or corrective actions, identitied during the review, will be addressed in a supplement to this LER.

NRC FORM 366A {6-1996)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I6-1999)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITYNAME (1) DOCKET I2) LER NUMBER I6) PAGE I3)

Cook Nuclear Plant Unit 1 05000-315 YEAR SEQUENTIAL NUMBER REVISION 4 OF 4 NUMBER 1999 018 00 TEXT (Ifmore spaceis required, use additional copios of NRC Form 366AI {17)

As part of the Cook Nuclear Plant Restart Plan, a Programmatic Readiness Review will be performed to assess the MOV Program and address improvements necessary to support the restart effort and establish a basis for continued improvement in CNP performance beyond plant restart.

SIMILAR EVENTS 3'I 5/96-006-00 315/98-059-00 NRC FOAM 366A (6-1996)