ML17329A563

LER 92-006-00:on 920618 & 19,10 of 20 Main Steam Safety Valve Lift Settings Found Outside of TS Tolerances.Caused by Setpoint Drift.Valves Reset to Acceptable Values & Retested satisfactorily.W/920717 Ltr

ML17329A563
Person / Time
Site:	Cook
Issue date:	07/17/1992
From:	Blind A, Weber G INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-006-02, LER-92-6-2, NUDOCS 9207230287
Download: ML17329A563 (11)

Text

Indiana Michigan Power Company

.j

~

Cook Nuclear Plant Qne Cook Place Briogman. Ml 49106 616 465 5901 lNPlANA NlCHlGAN POWER July 17, 1992 United States Nuclear Regulatory Commission Document Control Desk Rockville, Maryland 20852 Operating Licenses DPR-58 Docket No. 50-315 Document Control Manager:

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

92-006-00 Sincerely, k.g erat'.

A. Blind Plant Manager

/sb Attachment c: D. H. Williams, Jr.

'A. B..

E. E.

Davis, Regi~on Fitzpatrick III P. A. Barrett R.

B.

NRC F. Kroeger Walters Ft. Wayne Resident Inspector J. F. Stang NRC gV J. G. Keppler M. R. Padgett G. Charnoff, Esq.

D. Hahn INPO S. J. Brewer/B. P. Lauzau B. A. Svensson

NRC FORM 345 U.S. NUCLEAR REGULATORY COMMISSION (54)91 APPROVED OMB NO. 3)504)04 EXPIRES: 4(30I92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LlCENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO TH'K RECORDS AND REPORTS MANAGEMENT BRANCH (PB30). U.S. NUCLEAR RKGULATORY COMMISSION. WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3(5001041, OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, OC 20503.

FACILITYNAME (I) DOCKET NUMBER (2( PA E L Hd D. C. COOK NUCLEAR PLANT UNIT 1 0500031510F04 FAILURE OF THE UNIT ONE MAIN STEAM SAFETY VALVES TO MEET TECHNICAL SPECIFICATION LIFT SETPOINT REQUIREMENTS EVENT DATE (d) LER NUMBER ldl REPORT DATE (7) OTHER FACILITIES INVOLVED ldl "KAR SEQUENTIAL Pg$ FACIL(TY NAMES OOCKE'T NUMBERISI MONTH OAY YEAR ar'r NUM 4 4 R:MS NUME4 II MONTH DAY YEAR 0 5 0 0 0 0 6 189 2 9 2 0 0 6 00 07 7 9 2 0 5 0 0 0 THIS RKPORT IS SUBMITTED PURSUANT 7 0 THE REQUIREMENTS OF 10 CFR ('lt (Check onc or moro Of tnc fpllowinPI (11 OPERATING MODE IE) 20.402(dl 20A05(cl 50.73(cl(2)(N) 73.7)(II)

POWER 20.405(c) (1)dl 50.34(el(1) 50.73(c) l2)(cl 73.71(cl I EVEL O 20A05(c IllI ld) 50.34(cl(2) 50.73(c l(2)(c4) OTHER (Specify ln Apltrccr Ocrow ond In Tent, NRC Form 20.405(oil)I(I(I) X d0.73(cl(2) II) 50.73(c I (2) I c(4 I I A) Sddll 20A05(c) l1) lie) 40.73(c I (2 I I 4 I 50.73(cl(2(brlEHBI 20AOBN) (1) Irl 50.7 3(c I (2 I IIIII 50.73(c) l2) Ic I LICKNSEK CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA COOK G. A. VEBER - PLANT ENGINEERING SUPERINTENDENT 616 46 5-5 901 COMPLETE ONE LINE. FOR EACH COMPONENT FAILURE OKSCRIBED IN THIS REPORT (13)

MANUFAC FPORTABLF. MANUFAC. EPORTABLE CAUSE SYSTEM COMPONENT TURER TO NPRDS SYSTEM COMPONENT TURER TO NPRDS X S B RV D 243 'N:N r c,3i%k SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPKCTED SUBMISSION YES III yct, complctc EXPECTED SUSEIISSIDII DATE! NO DATE 115) 1 02 092 ABSTRACT ILimfr to ICI)0 rpocct, I.A, cpprpcimctcfy Wlrccn tlnprc.tpcoc rypcryrrtrcn irncrl (14)

On June 18 and 19, 1992, with the Unit 1 Reactor in Mode 1 (power operation) at, 49 percent thermal power, ten of the twenty Main Steam Safety li.ft setti.ngs were found, during Surveillance testing, to be outside Valves'MSSVs) of the +/- one percent limi.t established in Technical Specifications. The ten out of tolerance MSSVs were all found to upper tolerance (+1 percent) limit. Six of the MSSVs had lift at values which exceeded the lift lift values that were out of tolerance by 16 psig or less. Three of the MSSVs had values of greater than 3 percent (between 34 and 39 psig). The other MSSV's value was out of tolerance by 6.23 percent '(67 psig).

lift The MSSVs at Cook are Dresser Model 3707RA Safety Valves. The cause of this event is attributed to setpoint drift which limits the ability of the MSSVs to consistently meet the established setpoint tolerance of +/- 1 percent.. The Root Cause of this drift is still under investigation. A Technical specification change request is being submitted to increase the tolerance limits to +/- three percent. This change will minimize the number of MSSV failures and is consistent with revi.sed testing standards developed by ANSI OM-1 Committee.

NRC Form 35d (509)

NRC FORM 388A (849)

LICENSEE EYENT REPORT (LER)

TEXT CONTINUATION U.S. NUCLEAR RKGULATORYCOMMISSION t APPROVED OMS NO. 31504)OA EXI'IRES: E)30/92 ESTIMATED SURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REOUESTI 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS ANO REPORTS MANAGEMENT SRANCH (P430). U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT 13150410ll. OFFICE OF MANAGEMENTAND BUDGET.WASHINGTON, DC 20503.

FACILITY NAME ul DOCKET NUMSER 11) LER NUMSKR LS) PAGE (3)

YEAR :SEOUENTIAI. 3gj5 AEVOION NVMOER NVMSEII D. C. COOK NUCLEAR PLANT UNIT 1 0 315 92 0 0 6 00 02 OF 0 4 TEXT IIImom <<>>c>> JI ISO>>)oo( I>>o odWonel HRC FomI 85M'EJ ()T)

Conditio s Prior to Occurrence:

Unit One - 49 Percent Reactor Thermal Power Des i tion of Event:

On June 18 and 19, 1992, ten of the twenty Main Steam Safety Valves (MSSVs)

(EZZS/SB-RV) lift settings were found outside of the +/- one percent tolerance limits'established in Unit 1 Technical Specification 3.7.1.1. The ten outmf-tolerance MSSVs were all found to upper tolerance (+1 percent) limit. Six of the MSSVs had lift at values which exceeded the lift lift values that were out>>of-tolerance by 16 psig or less. Three of the MSSVs had values of greater than 3 percent (between 34 and 39 psig). The other MSSV's value was out-of-tolerance by 6.23 percent (67 psig).

lift The MSSVs at Cook are Dresser Model 3707RA Safety Valves. Based on operating experience and vendor input, the valve lift setpoints cannot be consistently maintained. within +/- one percent tolerance limits. A Technical Specification change request is being submitted to increase the tolerance limits to +/-

three percent. This Technical Specification change will minimize the number of. MSSV failures and is consistent with revised testing standards developed by ANSI OM-1 Committee.

The required relief pressure setpoint ranges and the as-found setpoints for MSSVs found out of specification are listed belows Percent Valve T/S Allowable As Found out of Date 06-.3.8-92 1-SV-1A-1 1065 1054-1076 1115 3.7 06-18-92 1-SV-2B-1 1075 1064-1086 1153 6.2 06-18 92 1-SV-3-1 1085 1074-1096 1098 0.2 06-18-92 1-SV-2A-4 1075 1064-1086 1091 0.5 06-18-92 1-SV-2B-4 1075 1064-1086 1121 3.3 06-19-92 1-SV>>1A>>2 1065 1054-1076 1112 3.4 06-19 92 1-SV-1B-2 1065 1054-1076 1078 0 2 06-19-92 1-SV-2A-2 1075 1064-1086 1091 0.5 06-19 92 1-SV-2B-2 1075 1064-1086 1102 1.5 06-19-92 1-SV-1B-3 1065 1054-1076 1096 1.9 There were no other inoperable structures, systems, or components that contributed to this event.

Cause of Event:

The cause of this event is attributed to setpoint drift which limits the ability of the MSSVs to consistently meet the established setpoint tolerance of +/- 1 percent. The Root Cause of the setpoint drift is still under investigation with the vendor.

NRC Form 388A (889)

'NRC FORM 355A IBB9) t LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION UN. NUCLEAR REGULATORY COMMISSION t APPROVED OMS NO. 3150010A EXPIRKS: l/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REOUESTI 603) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH IP430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO 1HE PAPERWORK REDUCTION PRO/ECT 13)600104). OFFICE OF MANAGEMENTANO BUDGET, WASHINGTON, OC 20503.

FACILITY NAME III DOCXKT NU~BER u) LER NUMSKR LS) PAGE IS)

YEAR SEQUENTIAL )&3 Af,VISION NVMIISII NUMSSII os000315

'Pr'06 D. C. COOK NUCLEAR PLANT UNIT 1 9 2 0 0 0 3 0 4 TEXT /// more e/reoe /o /e//rkerL Iree er/deere/NRC %%dnrr 3/)SI3/ 112)

Cause of Event Con i ued:

The updated report will be submitted by October 20, 1992 to provide any additional information obtained from the repair/evaluation activities.

l sis of Eve t:

The safety valve lift setpoints reported here were found to be out of compliance with the Technical Specification (T/S) 3.7.1.1 requirements and therefore-'reportable per 10CFRS0.73(a)(2)(i)(B). The as-found condition of the MSSVs did not have any impact on the health or safety of the public.

Out of the ten Main Steam Safety Valves, with high between 1 and 3 percent above the Technical Specification Limit. The lift setpoints, six opened remaining four had lift setpoints that were out-of-tolerance by more than 3 percent. While all ten of these valves violated the operability condition of Technical Specification 3.7.1.1, an analysis has been performed by Westinghouse to allow increasing the setpoint tolerance from +/- 1 percent to +/- 3 percent. This analysis will be submitted to the NRC in support of a Technical Specification change.

Based on the new Westinghouse analysis, the loss of load/turbine trip and small break LOCA events are the limiting transients with respect to the as-found MSSV lift setpoint values.

Zn the case of the loss of load/turbine trip event, the greatest demand on the MSSVs is created. Based on the Westinghouse analysis, the steam relief capacity of 8000 ft3/sec would be required to compensate for the transient.

The MSSVs available (16 MSSVs within 3 percent of Technical Specification Setpoint) would have provided sufficient relief capacity (10,304 ft3/sec).

The full flow capacity of each valve is 238 ibm/sec at 1186.5 psig or about, 644 ft3/sec. Therefore, the 16 MSSVs/ which opened within 3 percent of the Technical Specification limit, would have a discharge capacity of 10,304 ft3/sec of steam. An unacceptable pressure build-up would not have occurred, since two or more valves in each steam generator would have opened within 3 percent of their setpoints.

Zn the case of the small break LOCA analysis, the secondary system flow aids in the reduction of RCS pressure. The primary purpose of the MSSVs is maintaining steam generator pressure over the long term. Any MSSV being within the 3 percent range of the lowest Technical Specification setpoint (1065 psig) will provide sufficient flow to 'allow the pressure to remain within the analyzed bounds. Again, two or more valves per steam generator would have operated within the 3 percent range; therefore, this condition will be met The as-found MSSV setpoints would not have an adverse impact on the Reactor Coolant System (RCS) overpressure protection or Departure from Nucleate Boiling (DNB) ratio. The RCS is protected from overpressure conditions by the Pressurizer Safety Valves and Power Operated Relief Valves. In addition, the Steam Generator Power Operated Relief Valves can be used for RCS heat removal.

NRC Form 355A 1609)

NRC FORM355A US. NUCLEAR REGULATORY COMMISSION (54)9) APPROVEO OMB NO. 3150d(04 EXP(RES( 4l30(92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVE T REPORT ILER) INFORMATION COLLECTION REQUEST: 600 HRS. FORWARD COMMENTS REGARDIHG BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION ANO REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON. OC 20556, AND TO THE PAPERWORK REDUCTION PROJECT (3150d104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACII.ITY NAME (11 DOCKET NUMBER (2) LER NUMBER (5) PAGE (3)

YEAR SSOUSNTIAL REVISION NUMSEII NUMSSR D. C.

TEXT II/AS SPSCS *ISSIR'RNI. VSS ~

COOK NUCLEAR PLANT UNIT lVRC %%dnn 3554'4) ()7) 1 o 5 o o o 31 592 0 0 6 00 04 OF 04 A a sis of Event Cont ueds The LOCA long term cooling, hot leg switchover, LOCA blowdown, and Containment integrity analyses do not model the Main Steam Safety Valves, and are therefore not impacted.

Co rective etio All Safety ranges were reset Valves found with lift setpoints outside the acceptable setpoint to acceptable values and retested satisfactorily.

The MSSVs that were out of tolerance by more than 3 percent will be disassembled and refurbished during the current Refueling Outage. Any additional corrective actions will be included in the updated report.

Based on ANS1'M>>l Committee Safety Valve Test Requirements, steps are currently being taken to request a change to Technical Specification 3.7.1.1 MSSV lift setpoint tolerance from one percent to three percent.

Fa ed Com e t Xdentlficat o:

Main Steam safety Valve Manufacturers Dresser Consolidated Valves Models 3707RA-RT22 EZXS Code: SB-RV Previous Si lar Events:

50-315/90-13 50-3 16/92-03 50-315/89-02 50-316/90-06 50-315/87-11 50-316/88-04 50-315/86-20 NRC Form 355A (559)

ACCELERATED DI UTION DEMON TION SYSTEM REGULATO INFORMATION DISTRIBUTION ~STEM (RIDS)

ACCESSION NBR:9207230287 DOC.DATE: 92/07/17 NOTARIZED: NO DOCKET FACZL:50-315 Donald C. Cook Nuclear Power Plant, Unit 1, Indiana M 05000315 2'aUTH.NAME AUTHOR AFFILIATION WEBER,G.A. Indiana Michigan Power Co. (formerly Indiana & Michigan Ele BLIND,A.A. Indiana Michigan Power Co. (formerly Indiana & Michigan Ele RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 92-006-00:on 920618 & 19,failure of unit one main steam safety valves TS setpoint drift. Safety lift setpoint requirements. Caused by Valves were reset.W/920717 ltr.

DISTRIBUTION CODE: IE22T, COPIES RECEIVED:LTR TITLE: 50.73/50.9 Licensee Event Report (LER), Q ENCL Incident g SIZE:

Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ZD CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD3-1 LA 1 1 PD3-1 PD 1 1 STANG,J 1 1 INTERNAL: ACNW 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2" NRR/DST/SELB 8D 1 1 NRR/DST/SICB8H3 1 1 .R7t'D~ LB8D1 1 1, NRR/DST/SRXB 8E 1 1 REG FIL 02 1 1 RES/DSIR/EIB 1 1 G FILE 01 1 1 EXTERNAL: EG&G BRYCEPJ.H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POORE,W. 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEEDI FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 30 ENCL 30

Indiana Michigan Power Company Cook Nuclear Piant One Cook Place Bridgrnan, Ml 49106 616 465 5901 INDIANA NICHIGAN POWER July 17, 1992 United States Nuclear Regulatory Commission Document Control Desk Rockville, Maryland 20852 Operating Licenses DPR-58 Docket No. 50-315 Document Control Manager:

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

92-006-00 Sincerely, Pg A. A. Blind Plant Manager

~

/sb Attachment ci D. H. Williams, Jr.

A. B. Davis, Region

'E. E. Fitzpatrick III P. A. Barrett R. F. Kroeger B. Walters Ft. Wayne NRC Resident Inspector J. F. Stang NRC J. G. Keppler M. R. Padgett G. Charnoff, Esq.

D. Hahn INPO S. J. Brewer/B. P. Lauzau B. A. Svensson 9207230287 920717 PDR ADOCK 05000315 8 PDR

NRC FORM 366A (669)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION t APPROVED OMB NO. 31504)104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS, FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P630), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31504)104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEQUENTIAL ~~oar'EVISION YEAR yp NUMSER '< 6 NUMBER D. C. COOK NUCLEAR PLANT UNIT 1 0 0 315 '92 0 0 6 0 0 020" 0 4 TEXT //I m<<o Spoco ls oeII/rN/ Irro /I)/ooo/ HRC %%drm 388AS/ (ill Conditions Prior to Occurrence:

Unit One 49 Percent Reactor Thermal Power escri tion of Event:

On June 18 and 19, 1992, ten of the twenty Main Steam Safety Valves (MSSVs)

(EZIS/SB-RV) lift setti.ngs were found outside of the +/- one percent tolerance limits established in Unit 1 Technical Specification 3.7.1.1. The ten out-of-tolerance MSSVs were all found to upper tolerance (+1 percent) limit. Six of the MSSVs had lift at values which exceeded the lift lift values that were out-of-tolerance by 16 psig or less. Three of the MSSVs had values of greater than 3 percent (between 34 and 39 psig). The other MSSV's value was out-of-tolerance by 6.23 percent (67 psig).

lift The MSSVs at Cook are Dresser Model 3707RA Safety Valves. Based on operating experience and vendor input, the valve lift maintained within +/- one percent tolerance limits. A Technical Specification setpoints cannot be consistently change request is being submitted to increase the tolerance limits to +/-

three percent. This Technical Specification change will minimize the number of MSSV failures and is consistent with revised testing standards developed by ANSI OM-1 Committee.

The required relief pressure setpoint ranges and the as-found setpoints for MSSVs found out of specification are listed below:

E Percent Valve T/S Allowable As Found out of Date I.D. No. ~pere Tolerance 06-18-92 1-SV-1A-1 1065 1054-1076 1115 3.7 06-18-92 1-SV-2B-1 1075 1064-1086 1153 6.2 06-18-92 1-SV-3-1 1085 1074-1096 1098 0.2 06-18-92 1-SV-2A-4 1075 1064-1086 1091 0.5 06-18-92 1-SV-2B-4 ,1075 1064-1086 1121 3' 06-19-92 1-SV-1A-2 1065 1054-1076 1112 3.4 06-19-92 1-SV-1B-2 1065 1054-1076 1078 0.2 06-19-92 1-SV-2A-2 1075 1064-1086 1091 0.5 06-19-92 1-SV-2B-2 1075 1064-1086 1102 1.5 06-19-92 1-SV-1B-3 1065 1054-1076 1096 1.9 There were no other inoperable structures, systems, or components that contributed to this event.

Cause of Event:

The cause of this event is attributed to setpoint drift which limits the ability of the MSSVs to consistently meet the establi.shed setpoint tolerance of +/- 1 percent. The Root Cause of the setpoint drift is still under investigation with the vendor.

NRC Form 368A (889)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31500104 ~

(64)9)

EXP IR ES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P.530), V.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT 131500104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, OC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR jg SEOUENTIAL 3&F REVISION NUMBER '>4 NUMBER D. C. COOK NUCLEAR PLANT UNIT 1 05000 31 5 9 2 006 0 0 03 OF 0 4 TEXT /// more Aoeoe Jr A//I(bred, Iree edd/dorN/H/IC Form 36643/ ((2)

Cause of Event Continued:

The updated report will be submitted by October 20, 1992 to provide any additional information obtained from the repair/evaluation activities.

nal sis of Event:

The safety valve 'lift setpo'ints reported here were found to be out of with the Technical Specification (T/S) 3.7.1.1 requirements and 'ompliance therefore reportable per 10CFR50.73(a)(2)(i)(B). The as-found condition of the MSSVs did not have any impact on the health or safety of the public.

Out of the ten Main Steam Safety Valves, with high between 1 and 3 percent above the Technical Specification Limit. The lift setpoints, si'x opened remaining four had lift setpoints that were out-of-tolerance by more than 3 percent. While all ten of these valves violated the operability condition of Technical Specification 3.7.1.1, an. analysis has been performed by Westinghouse to allow increasing the setpoint tolerance from +/- 1 percent to +/- 3 percent. This analysis will be submitted to the NRC in support of a Technical Specification change.

Based on the new Westinghouse analysis, the loss of load/turbine trip and small break LOCA events are the limiting transients with respect to the as-found MSSV lift setpoint values.

In the case of the loss of load/turbine trip event, the greatest demand on the MSSVs is created. Based on the Westinghouse analysis, the steam relief capacity of 8000 ft3/sec would be required to compensate for the transient.

The MSSVs available (16 MSSVs within 3 percent of Technical Specification Setpoint) would have provided sufficient relief capacity (10,304 ft3/sec).

The full flow capacity of each valve is 238 ibm/sec at 1186.5 psig or about 644 ft3/sec.. Therefore, the 16 MSSVs, which opened within 3 percent of the Technical Specification limit, would have a discharge capacity of 10,304 ft3/sec of steam. An unacceptable pressure build-up would not have occurred, since two or more valves in each steam generator would have opened within 3 percent of their setpoints.

Zn the case of the small break LOCA analysis, the secondary system flow aids in the reduction of RCS pressure. The primary purpose of the MSSVs is maintaining steam generator pressure over the long term. Any MSSV being within the 3 percent range of the lowest Technical Specification setpoint (1065 psig) will provide sufficient flow to 'allow the pressure to remain within the analyzed bounds. Again, two or more valves per steam generator would have operated within the 3 percent range; therefore, this condition will be met.

The as<<found MSSV setpoints would not have an adverse impact on the Reactor Coolant System (RCS) overpressure protection or Departure from Nucleate Boiling (DNB) ratio. The RCS is protected from overpressure conditions by the Pressurizer Safety Valves and Power Operated Relief Valves. In addition, the Steam Generator Power Operated Relief Valves can be used for RCS heat removal.

NRC Form 366A (669)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED 0MB NO. 31500104 (669)

EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMaTION COLLECTION REQUEST: 50,0 HAS. FORWaRD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPOATS MANAGEMENT BRANCH (P4301, U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555,.AND TO I 1HE PAPERWOAK REDUCTION PROJECT (31504)104), OFFICE'F MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEQUENTIAL REVISB) N YEAR .jg NUMBER NUM ER D. C. COOK NUCLEAR PLANT UNIT I o 5 o o o 31 5 0 0 6 00 04 OF 0 4 TEXT /I/IINuu EP4ce (I IBEBEBd, u>> Bddio'oINIHRC FBI 35//AB/ (12) nal si.s of Event Continued:

The LOCA long term cooling, hot leg switchover, LOCA blowdown, and Containment integrity analyses do not model the Main Steam Safety Valves, and are therefore not impacted.

Correcti.ve Action:

All Safety Valves found with lift setpoints outside the acceptable setpoint ranges were reset to acceptable values and retested satisfactorily.

The MSSVs that were out of tolerance by more than 3 percent wi.ll be disassembled and refurbished during the current Refueling Outage. Any additional corrective actions will be included in the updated report.

Based on ANSI OM-1 Committee Safety Valve Test Requirements, steps are currently being taken to request a change to Technical Speci.fication 3.7.1.1 MSSV lift setpoint tolerance from one percent to three percent.

Failed Com onent Identification:

Main Steam Safety Valve Manufacturer: Dresser Consolidated Valves Model: 3707RA-RT22 EIIS Codes SB-RV Previous Similar Events:

50-315/90-13 50-316/92-03 50-315/89-02 50-316/90-06 50-315/87-11 50-316/88-04 50-315/86-20 NRC FBIBI 366A (64)9)