ML17331B401

LER 94-001-01:on 940203,04 & 05,13 of 20 MSSVs Lift Settings Found Out of Tolerance.Caused by Mild Galling Between Disk & Nozzle Components.Valve Mfg Recommended That Nozzle & Disc Seatingsurfaces Have Grey Matt finish.W/940527 Ltr

ML17331B401
Person / Time
Site:	Cook
Issue date:	05/27/1994
From:	Blind A, Weber G INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-94-001, LER-94-1, NUDOCS 9406010230
Download: ML17331B401 (8)

Text

ACCELERATED DISTRIBUTION SYSTEM DEMONSTRATION REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9406010230 DOC.DATE: 94/05/27 NOTARIZED: NO DOCKET FACIL:50-315 Donald C. Cook Nuclear Power Plant, Unit 1, Indiana M 05000315 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 94-001-01:on 940205,thirteen of twenty MSSVs settings were found out of tolerance. Caused by disc was lift found to have been, covered with mixed iron-chromium oxides. D Corrective action:MSSV was repaired & retested.W/940527 ltr.

ncidentURpt, etc.

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

NOTES:

RECIPIENT COPIES RECIPIENT COPIES D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD3-1 PD 1 1 HICKMAN,J 1 1 D INTERNAL:,AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DS P 2 2 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRI L/RPEB 1 1 NRR/DRSS/PRPB 2 2 RR/SSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 G- 02 1 1 RES/DSIR/EIB 1 1 RGN3 FILE 01 1 1 EXTERNAL: EG&G BRYCE,J.H 2 2 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 D

A D

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOiVI Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

Indiana Michigan~

Power Company

~

Cook Nuclear Plant One Cook Place Bridgman, Ml 49106 616 465 5901 IMAMMA NICHIGAN PEVER May 27, 1994 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:

94-001-01 Sincerel A.

!d~~

Blind V~

Plant Manager

/sb c'.

Attachment E.

P.

B. Martin, Region III-E. Fitzpatrick A. Barrett R. F. Kroeger M. A. Bailey Ft. Wayne NRC Resident Inspector J. B. Hickman NRC J. R. Padgett G. Charnoff, Esq.

D. Hahn INPO S. J. Brewer 94060102~0 940527 PDR ADOCK 05000315

'PDR S Pg(~

NRC FORM 366 . NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 (5-92) EXPIRES 5/31/95 EsTIMATED BURDEN pER REspoNsE To coMpLY vriTH THts INFORLrATION COLLECTION REOVEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150.0104), OFRCE OF (See reverse for required number of digits/characters for each block) MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACIUTY tlAtIE (I) DOCKET tlUMBER (2) PAGE P)

D. C. COOK NUCLEAR PLANT UNIT 1 O5OOO 315 1 OF 5 FA'ILURE OF THE UNIT ONE MAIN STEAM SAFETY VALVES TO MEET TECHNICAL SPECIFICATION LIFT SETPOINT RE UIREMENTS I EVENT DATE 5 LER NUMBER 6 REPORT NUMBER 7 OTHER FACILITIES INVOLVED 8 SEOVENTIAL REVISION FACIUIYNAME DOCKET NUMBER DAY YEAR YEAR MONTH DAY YEAR NUMBER NUMBER Cook Unit 2 050003] 6 FACIUTY NAME DOCKET NUMBER 02 05 94 94 001 01 05 27 94 05000 OPERATING THIS REPORT IS SUBMITTED PURSUA NT TO THE REQUIREMENTS OF 10 CFR i: Check one or more 11 MODE (9) 20.402(b) 20.405(c) 50.73(a) (2)(iv) 73.71(b)

POWER 20.405(a) (1)(i) 50.36(c) (1) 50.73(a) (2) (v) 73.71(c)

LEVEL (10) 062 20.405(a) (1)(ii) 50.36(c) (2) 50.73(a)(2)(vii) OTHER 20.405(a) (1) (iii) 50.73(a) (2) (i) 50.73(a) (2) (viii)(A) (Specify In Abetract betow and In Text, NRC 2o.405(a) (1) (iv) 50.73(a) (2) (ii) 50.73(a) (2) (viii)(8) Form 366A) 20.405(a) (1) (v) 50.73(a) (2) (iii) 50.73(a) (2)(x)

LICENSEE CONTACT FOR THIS LER 12 NAME TELEPHONE NUMBER snctude Area Code)

G. A. WEBER PLANT ENGINEERING SUPERINTENDENT (616) 465-5901 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13 REPORTABLE REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TO NPRDS TO NPRDS X SB RV D243 SUPPLEMENTAL REPORT EXPECTED 14 EXPECTFD lrl'ONTH DAY YES NO SUBMISSION (If yea, comptete EXPECTED SUBMISSION DATE) DATE (15)

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

Thi.s supplemental report is bei.ng submitted to provide additional information regarding the Main steam Safety Valve Lift Setpoint testing initially reported on March 7, 1994. On February 3, 4, and St 1994r with the Uni.t'1 Reactor in Mode 1 (power operation) at 62 percent Thermal Power, thi.rteen of the twenty Main Steam Safety~Valves'MSSVs) lift settings were found out of tolerance as established in Technical Specifications during Surveillance testing. Due to the results of the Unit 1 MSSV testing, the MSSVs in Unit, 2 were also tested.

Nine Unit 2 MSSVs were found out of specification. Based on the Safety Evaluati.on conducted for this event, the MSSV as-found setpoints did not exceed the design pressure rating of the steam generators in either Unit 1 or Unit 2. The most likely cause of this event is attributed to mild galling between the disk and nozzle components along with "mechanical keying" and/or chemical reaction of the mixed oxides on the disk with the chromium oxide on the nozzle. Zt is believed these combined affects, over'ime, caused the elevated lift setpoint on the MSSV's initial lifts. Corrective actions are being pursued which will include approval for the following: 1) Exercising the MSSVs mid-cycle to improve valve setpoint performance; 2) Develop in-house test capabilities; obtain spare MSSVs; 4) work with vendor and another utility to develop 3) a long term solution to the di.sc/nozzle binding problem.

NRC FORM 366 (5-92)

REQUIRED NUMBER OF DIGITS/CHARACTERS FOR EACH BLOCK BLOCK NUMBER OF TITLE NUMBER DIGITS/CHARACTERS UP TO 46 FACILITYNAME 8 TOTAL DOCKET. NUMBER 3 IN ADDITION TO 05000 VARIES PAGE NUMBER UP TO 76 TITLE 6 TOTAL

'2 PER BLOCK EVENT DATE 7 TOTAL 2 FOR YEAR LER NUMBER 3 FOR SEQUENTIAL NUMBER 2 FOR REVISION NUMBER 6 TOTAL REPORT DATE 2 PER BLOCK UP TO 18 <<FACILITY NAME OTHER FACILITIES INVOLVED 8 TOTAL DOCKET NUMBER 3 IN ADDITION TO 05000 OPERATING MODE

'OWER 10 LEVEL 1

REQUIREMENTS OF 10 CFR CHECK BOX THAT APPLIES UP TO 50 FOR NAME 12 LICENSEE CONTACT 14 FOR TELEPHONE CAUSE VARIES 2 FOR SYSTEM 13 4 FOR COMPONENT EACH COMPONENT FAILURE 4 FOR MANUFACTURER NPRDS VARIES 1

14 SUPPLEMENTAL REPORT EXPECTED CHECK BOX THAT APPLIES 6 TOTAL 15 EXPECTED SUBMISSION DATE 2 PER BLOCK

NRC FORM 388A US. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31504))04 (889)

EXPIRES: 4/30/92 IMATEO BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EV T REPORT (LER) INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION ANO REPORTS MANAGEMENT BRANCH (P830). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, OC 20503, FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER LB) PAGE (3)

YEAR SEQVENZIAL REVISION NVMSEII NVMSEII D. C. COOK NUCLEAR PLANT UNIT 1 osooo3 159 4 001 0 1 0 2 OF 05 TEXT ///more epece /4 n Jrr/rerL Iree 4//OO 'oe/ HRC Form 3r//LIB/ (12)

Conditions Prior to Occurrence:

Unit One Mode 1 (power operation) at 62 percent Reactor Thermal Power Descri tion of Event:

This supplemental report is being submitted.to provide additional information regarding the Main Steam Safety Valve Lift Setpoint testing initially reported on March 7, 1994.

February 3, 4, and 5, 1994 thirteen of the twenty Main Steam Safety Valves On (MSSVs) (EIIS/SB-RV) lift settings were found outside of the +/- one percent tolerance limits established in Unit 1 Technical Specification 3.7.1.1. Three of the MSSVs lifted between 1 and 3 percent high. Nine MSSVs lifted between 3 and 6.9 percent high. One MSSV had a high (1180 psig). This is the maximum lifting pressure obtainable by the test lift pressure greater than 9.8 percent equipment.

The MSSVs at Cook are Dresser Model 3707RA Safety Valves. Based on operating experience and vendor input, the valve maintained within +/- one percent tolerance limits.

lift setpoints cannot be consistently The required relief pressure setpoint ranges and the as-found setpoints for the MSSVs found out of specification are listed below:

Valve T/S Allowable As Found Percent Date 02-04-94 1-SV-1A-1 1 1065 1054-1076 1103 .3.6 02-04-94 1-SV-1B-1 1 1065 1054-1076 1099 3.2 02-05-94 1-SV-2B-1 1 1075 1064-1086 >1180 >9.8 02-04-94 1-SV-1A-2 1065 1054-1076 1135 6.6 02-04-94 1-SV-2A-2 1075 1064-1086 1116 3.8 02-04-94 1-SV-2B-2 1075 1064-1086 1101 2 '

02-04-94 1-SV-3-2 1085 1074-1096 1145 5.5 02-03-94 1-SV-1B-3 1065 1054-1076 1123 5.4 02-03-94 1-SV-3-3 1085 1074-1096 1117 2.9 02-05<<94 1-SV-1A-4 1065 1054-1076 1085 1.9 02-05-94 1-SV-1B-4 1065 1054-1076 1125 5.6 02-05-94 1-SV-2A-4 1075 1064-1086 1127 4.8 02-05-94 1-SV-2B-4 1075 1064-1086 1149 6.9 Retests were performed on the to make necessary setpoint adjustments and ensure as-left lift MSSVs setpoints were acceptable. The subsequent revealed that sticking was experienced on the initial lifts and was not MSSV tests indicative of the actual setpoint values. Ten of the MSSVs were found to be set correctly and required no adjustment. Two of the MSSVs had lift setpoints that were slightly below acceptable values and adjustments were needed to raise the lift setpoints to meet the Technical Specification Acceptance Criteria.

NRC Form 388A (889)

NRC FORM 356A US. NUCLEAR REGULATORY COMMISSION (6J)9) APPROVED OMB NO. 31500)04 EXPIRES: e/30/92 TIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUESTS 50A) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLFAR REGULATORY COMMISSION. WASHINGTON, OC 20555. AND TO 1HE PAPERWORK REDUCTION PROJECT (31504104). OFFICE OF MANAGEMENTAND BUDGET,WASHINGTON. DC 20503.

FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (51 PAGE IS)

YEAR SEOVESITIAL J'GG RSVOION NUMBER %4 NVM ea D. C. COOK NUCLEAR PLANT UNIT 1 o 5 o o o 31 59 4 001 0 1 0 30F 0 5 TEXT /// m<<e <<>>ce /e /<<Jo//<<L we <</d/o<<>>/NRC Foml 35EA9/ (17)

Descri tion of Event continued:

With the poor performance of the Unit 1 MSSVs, testing was performed on the Unit 2 MSSVs. Nine Unit 2 MSSVs were found to exceed the +/- one percent Technical Specification Acceptance Criteria. However, all'ine of the Unit 2 MSSVs were within three percent of the Technical Specification Setpoint.

The required relief pressure setpoint ranges and the as-found setpoints for

.the MSSVs found out of specification are listed below:

Valve T/S Allowable As Found Percent Date I.D. No. Stm. Gen. ~PSIG Deviation 1

02-11-94 2-SV-1B-1 1065 1054-1076 1083 1.7 02-11-94 2-SV-2A-1 1075 1064-1086 1052 2.1 02-12-94 2-SV-1A-2 1065 1054-1076 1088 2.2 02-12-94 2-SV-2A-2 1075 1064-1086 1087 1~1 02-10-94 '-SV-2B-2 1075 1064-1086 1097 2.0 02-12-94 2-SV-2B-3 3 1075 1064-1086 1092 1.6 02-11-94 2-SV-1B-4 1065 1054-1076 1091 2.4 02-11-94 2-SV-2B-4 1075 1064-1086 1089 1.3 02-11-94 2-SV<<3-4 1085 1074-1096 1062 2.1 Retests were performed on the to make necessary setpoint adjustments and ensure as-left lift MSSVs setpoints were acceptable. The subsequent revealed that sticking was experienced on the initial lifts and was not MSSV tests indicative of the actual setpoint values. Seven of the MSSVs were found to be set correctly and required no adjustment. Two of the MSSVs had lift setpoints that were below acceptable values and adjustments were needed to raise the lift setpoints to meet the Technical Specification Acceptance Criteria.

There were no other inoperable structures, systems, or components that contributed to this event.

On February 5, 1994, at 1600 Hours, this event was reported as a One Hour Report to the U. S. Nuclear Regulatory Commission Operations Center, per 10CFR 50.72(b)(ii)(B). The One Hour Report was submitted since the as-found condition of the MSSVs may have been a condition that was outside the design basis of the plant.

Following completion of the MSSV testing in both Unit 1 and Unit 2, an inaccuracy was discovered in the test method used by the vendor performing the MSSV Lift Setpoint Trevi Testing. The Trevi Test inaccuracy was reported in LER 50-315/94-003. The findings, reported in this LER (50-315/94-001) reflect the findings of the original MSSV deficiency only.

NRC Foml 356A (6 69)

NRC FORM 366A 16 JIB)

I LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION US NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31500104 EXPIRES: O/30/92 TIMATED 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 (P.530). U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500)(MI, OFFICE OF MANAGEMENTAND BUDGET. WASHINGTON, DC 20503.

FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (6) PAGE IS)

SEOUENTIAI o'cX'EVISION NUMSEII <5 NUMBER l

D. C. COOK NUCLEAR PLANT UNIT 1 0 5 0 0 0 3 1 5 9 4 001 0 1 O 4 << O 5 TEXT //I mo/o Jpoco b ooq/ftN/ opt PI/O)mo/ NRC Fom/ 36SAB/ 112)

Cause of Event:

The most likely cause of this event is attributed to mild galling between the disk and nozzle components along with "mechanical keying" and/or chemical reaction of the mixed oxides on the disk with the chromium oxide on the nozzle. It is believed these combined effects over time caused the elevated lift setpoint on the MSSV's initial lifts.

To determine the root cause, several of the MSSV discs were sent to an independent laboratory for analysis. Results of the analysis indicated that the contact surfaces of the discs were found to have been covered with mixed iron-chromium oxides over most of their surfaces except for islands of nozzle material. The nozzle material transfer most likely occurred by a galling or adhesive wear mechanism "rather than, a diffusion bonding process. The mixed oxides on most of the sealing surface are postulated to have developed from normal oxidation of the disk alloy along with possible deposition of iron-oxide particulates from the steam.

Both the Unit above findings.

1 and Unit 2 MSSV Particular attention lift setpoint failures'are attributed to the was paid to 1-SV-2B-1 during disassembly. MSSV 1-SV-2B-1 could not be lift tested since the capacity of the test equipment had been exceeded. No mechanical abnormalities were detected that would account for the as-found lift setpoint. The disc for 1-SV-2B-1 was found to have a greater scale thickness than observed on the other disc samples.

There is a definite correlation between the number of MSSV failures and the main steam pressure transi'ents/unit trips. With fewer transients occurring during an operating cycle, more MSSV failures would occur. As evidenced by the February, 1994 Unit 1.MSSV surveillance t'esting, the worst case experienced by either unit had followed a record run of 470 days.

Anal sis of Event:

This event is reportable via the provisions of 10CFR50.73(a)(2)(i)(B) as an operation prohibited by Plant Technical Specification 3.7.1.1. The Technical Specification 3.7.1.1 requires that the Main Steam Safety Valves be operable in Modes 1 through 3. Operability requires that all twenty Main Steam Safety Valves lift within +/- 1 percent of the Technical Specification Setpoints.

The Safety Evaluation revealed that the MSSV as-found have. resulted in exceeding the design rating of the steam generators.

lift setpoints would not After the initial lift pressure was obtained, the MSSVs would have went full open.

Full flow would have been obtained instantly. The MSSVs would not require an additional three percent pressure to reach a full flow condition.

A review of the Westinghouse Nuclear Safety Advisory Letter (NSAL-94-001, Operation at Reduced Power Levels with Inoperable MSSVs) was performed and reported via LER 050-315/94-003.

NR C Form SSSA (SJ) S)

NRC FOAM 388A U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMS NO. 31504)104 (84)9)

EXPIAES: 4/30/92 IMATED BURDEN PER RESPONSE'O COMPLY WTH THIS LICENSEE EV T REPORT ILER) INFORMATION COLLECTION REQUEST: 50A) HRS. FORWARD COMMENTS AEGAROINQ BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND AEPORTS MANAGEMENT BRANCH (P8301. U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON. DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (3)504))041. OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, OC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (8) PAGE (3)

YEAR SEQVENTIAL Pr'g: 4EVISION g$ NVMBE4:~/ NVM 84 D. C. COOK NUCLEAR PLANT UNIT 1 0 5 0 0 0 3 1 5 9 4 0 01 01 0 5 OF 0 TEXT /// mo/4 4poce JI PEV/IPIL IIw /dR/444 ~ HRC FBI 3(EL(3/ 02)

Corrective Action:

Ten of the Unit 1 and seven of the Unit 2 MSSVs wi.th the acceptable setpoint ranges retested satisfactorily and did not require any lift setpoints outside ad)ustments. Two Unit 1 MSSVs and two Unit 2 MSSVs required ad)ustment to return the setpoint to acceptable values. MSSV 1-SV-2B>>1 was repaired and retested along with all other Unit 1 and Unit 2 MSSVs.

The valve manufacturer has recently recommended that, the nozzle and disc seating surfaces have a grey matt finish instead of a mirror finish. The valve manufacturer believed that this action could reduce the sticking phenomena between the seats. A new lapping .procedure was employed during the repair of ten Unit 1 MSSVs during this Refueling Outage.

A Task Force was established to determine the cause for the MSSV Lift Setpoint problems. The Task Force and manufacturer believe that the safety valves could be exercised mid-cycle to clear the seat of any oxide buildup. This activity is being reviewed by the licensing group to determine its feasibility and safety concerns.

Other corrective actions being consi.dered at this time:

Purchasing our own test equipment.

Purchasing spare MSSVs.

Conti.nue to pursue a resolution to the MSSV sticking phenomena and continue to gather and share information with other plants and valve manufacturers. The cooperative effort will contribute to developing a long term solution to the disc/nozzle bonding problem.

Techni.cal Specifi.cation Change submitted to modify MSSV setpoint to +/- 3%. V Failed Com onent Identifications Main Steam Safety Valve Manufacturer: Dresser Consolidated Valves Model: 3707RA-RT22 EIIS Code: SB-RV Previous Similar Events:

50-315/92-06 50-316/92-03 50-315/90-13 50-316/90-06 50-315/89-02 50-316/88-04 50-315/87-11 50-315/86-20=

I(RC Form 388A (889)