ML17305A539
| ML17305A539 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 02/14/1990 |
| From: | Bradish T, James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-PT21-90, REF-PT21-90-028-000 192-00630-JML, 192-630-JML, LER-89-018, LER-89-18, PT21-90-028-000, PT21-90-28, NUDOCS 9002270070 | |
| Download: ML17305A539 (28) | |
Text
ACCELERATED+)ISTRIBUTION DEMO1TITRATION SYSIEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9002270070 DOC.DATE: 90/02/14 NOTARIZED: NO DOCKET FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 AUTH. NAME AUTHOR AFFILIATION BRADISH,T.R. Arizona Public Service Co. (formerly Arizona Nuclear Power LEVINE,J.M. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION
SUBJECT:
LER 89-018-01:on 891026,Henry Pratt Co valve failures.
W/8 ltr.
DISTRIBUTION CODE: IE28T COPIES RECEIVED:LTR ENCL SIZE:
TITLE: Licensee Event Report (LER) 6 Part 21 Rept Combzn tion (50 NOTES: 05000528 RECIPIENT RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 PETERSON,S. 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DS P 2 2 DEDRO 1 1 IRM TECH ADV 1 1 IRM/DCTS/DAB 1 1 NRR/ADP/DRP14E4 1 1 NRR/ADSP DIR 1 1 NRR/DET/ECMB 9H 1 '1 NRR/DET/EMEB9H3 1 1 NRR/DET/ESGB 8D 1 1 NRR/DLPQ/LHFBll 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB11 1 1 NRR/DOEA/OGCBll 1 1 NRR/DRE P/PRAB 1 0 1 1 NRR/DREP/PRPB11 2 2 I NRR/DRI S/RS B9A 1 1 NOTES'OPIES NRR/DRIS/RVIB9D NRR/DST/SELB 8D NRR/DST/SPLB8Dl NSIC SILVER,E 1
1 1
1 1
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1 NRR/DST 8E2 NRR/DST/SICB 7E NRR DST SRXB 8E EG F 1
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1 REGION 1 1 1 R 1 1 REGION 3 1 1 REGION 4 1 1 REGION 5 1 1 RES MORISSEAUiD 1 1 RES/DSIR/EIB 1 1 RES/DSR/PRAB 1 1 RGN5 FILE 01 1 1 EXTERNAL EGGG WILLIAMSg S 4 4 INPO RECORD CTR 1 1 L ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 I
NS C MURPHY i G ~ A 1 1 NUDOCS FULL TXT 1 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 NEEDr FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED'TTR 56 ENCL 55
l Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P.O. BOX 52034 ~ PHOENIX, ARIZONA 85072-2034 ID/I 192-00630-JML/TRB/DAJ JAMES M. LEVINE VICE PRESIDENT February 14, 1990 NUCLEAR PRODUCTION U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 1 Docket No. STN 50-528 (License No. NPF-41)
Licensee Event Report 89-018-01 File: 90-020-404, Attached please find Supplement Number 1 to Licensee Event Report (LER) No.
,89-018.-00 prepared and submitted pursuant to 10CFR50.73. In accordance with 10CFR50.73(d), we are herewith forwarding a copy of the LER to the Regional Administrator of the Region V office.
This report is also being submitted pursuant to 10CFR21 and includes the information requested in 10CFR21.21(b)(3). In accordance with 10CFR21.21(b)(2), three copies of this report are being provided to the Director, Office of Nuclear Reactor Regulation.
If you have any questions, please contact T. R. Bradish, (Acting) Compliance Manager at (602) 393-2521.
Very truly yours, JML/TRB/DAJ/kj Attachment cc: W. F. Conway (all with attachment)-
E. E. Van Brunt J. B. Martin T. E. Murley, 3 copies D. H. Coe T. L. Chan A. C. Gehr INPO Records Center B. Cummins 9002270070 900214 '8 PDR ADOCK 0 0005 S PDC:
NAC FOAM 366 U.S. NUCLEAR REGULATORY COMMISSIO NBS) APPAOVED OMB NO.31500104 EXPIRES: 4I30N2 ESTIMATED BURDEN PEA RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION AEQUESTI 60.0 HRS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE AECORDS AND RFPOATS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31600104). OFFICE OF MANAGEepENT AND BUDGET. WASHINGTON, DC 20503.
FACILITYNAME ('ll DOCKET NUMBER (2) PA Palo Verde Unit 1 0 5 0 0 o 5 28 1 oF1 2 TITLE (4)
Henr Pratt Company Valve Failures EVENT DATE (51 LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (5)
MONTH DAY YEAR YEAR@ SEOVENTIAL 'w5'UMBER NUMSER MONTH OAY YEAR I'ACILITY NAMES DOCKET NVMBEAIS)
Palo Verde Unit 2 0 5 0 0 0 5 2 9 1' 26 89 8 9 0 1 8 01 02 14 9 0 Palo Verde Unit 3 o 5o o o53 0 OPERATING THIS REPORT IS SUBMI'TTED PURSUANT TO THE REOUIREMENTS OF 10 CFR ()t IChrch one or morr ol thr IorlowinPI (11)
MODE (Sl 20A02(S) 73.7)(S) 20A06(c) 50,73(el(1) l iv)
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On October 17, 1989, two Unit 3 containment purge valves did not meet local leak rate testing (LLRT) acceptance criteria when they were being tested during a refueling outage. The valves are the inside and outside containment isolations for the exhaust portion of the Containment Purge System. The valves are 42-inch butterfly valves manufactured by Henry Pratt Company.
APS was performing a root cause of failure investigation for the two valves, and on October 26, 1989, information was developed which indicated that the valves had malfunctioned due to intergranular stress fracture and subsequent failure of spiral pins. The intergranular fracture was most probably the result of hydrogen embrittlement. The spiral pin failures allowed the valve discs to move axially resulting in excessive leakages The pins are manufactured from AISI 420 stainless steel. Subsequent investigation has revealed that similar spiral pins are installed in other valves in the Containment Purge System, Nuclear Cooling Water System, and Essential Cooling Water System.
As corrective action, the spiral pins are being replaced with 302 stainless steel replacements.
This report is also being provided pursuant to the requirements of 10CFR21.
NRC Form 366 (64)0)
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NRC FORM SEEA US. NUCLEAR REGULATORY COMMISSION APPROVEO 0MB NO.31500(0i (686) 6XPIAES: i)30/62 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUEST: 508) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPOATS MANAGEMENT BRANCH (P430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555. ANO TO THE PAPERWOAK REDUCTION PROJECT (31600)Oil. OFFICE OF MA NAG E MENT AND 6 UDG ET, WASHINGTON, OC 20503.
FACILITYNAME (11 DOCKET NUMBER (2) LER NUMBER (6) PAGE IS)
YEAR ~l~~ SEOVENTIAL V&1 AEV<<KIN 6(<<) NVMEEN ?4 NUMBER Palo Verde Unit 1 o s o o o 5 2 8 8 9 0 1 8 0 1 02 oF 1 2 TEXT (It m<<P <<face ii nivP<<6 NEE atdeonV HRC F<<m 35642) (IT)
This report is also being provided pursuant to the provisions of 10CFR21. The narrative below includes the information requested by 10CFR21.21(b)(3);
however, it is being formatted to report this event in accordance with the requirements of 10CFR50.73.
DESCRIPTION OF WHAT OCCURRED:
Initial Conditions:
The following plant conditions existed on October 26, 1989, when information was developed which indicated that the failures described herein were most probably the result of hydrogen embrittlement (i.e., common mode failure).
Palo Verde Unit 1 was in refueling outage with the core (AC) off-loaded to the Spent Fuel Pool (ND).
Palo Verde Unit 2 was in Mode 3 (HOT STANDBY) at normal operating temperature and pressure.
Palo Verde Unit 3 was in Mode 5 (COLD SHUTDOWN) during a refueling outage. The Reactor Coolant System (RCS)(AB) was at approximately 145 degrees Fahrenheit. (F) and 366 pounds per square inch-absolute.
Reportable Event Description (Including Dates and Approximate Times of Major Occurrences):
Event Classification: An event where a single cause resulted in two independent trains in a single system not being able to meet operability requirements.
Note: This section includes information requested by 10CFR21 concerning the nature of the defect and dates for which information was obtained/developed.
On October 17, 1989, two Unit 3 containment purge valves (VA)(ISV) did not meet local leak rate testing (LLRT) acceptance criteria.
The valves are the inboard and outboard containment isolations for the exhaust portion of the Containment Purge System (VA). The valves were declared inoperable at approximately 1815 MST (Note:
Unit 3 was in Mode 5; therefore, the containment purge valves were not required to be OPERABLE to meet a Technical Specification Limiting Condition for Operation.
NRC FENN 366A (569)
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NRC FORM SESA IAS. NUCLEAR AEOULATORYCOMMISSION APPROVED OMS NO. 21500104 IS J)9) 5 XP I A E S: 5/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT {LER) INFORMATION COLLECTION REOUESTI 503) HRS. FORWAAD COMMENTS REOARDINO BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAOEMENT BRANCH IP420), U.S. NUCLEAR AEOULATORY COMMISSION, WASHINOTON, DC 20555, AND TO THE PAPERWOAK REDUCTION PROJECT 121504105), OFFICE OF MANAOEMENTAND SUDQET,WASHINOTON, DC 20502.
FACILI'TY NAME O) DOCKET NUMBER 12) LEA NUMBER (5) PACE IS)
NUM 54 ~
SEOUENTIAL %~5 REVISION NUMSER Palo Verde Unit 1 o s o o o 5 28 89 01 8 01 0 3 oF 1 2 TEXT /I/mom NNco /I TN)vied. Uso ~ OR/ooo//VRC FomI SSSAS/ 117)
The containment purge valves are forty-two (42) inch butterfly valves. The valves utilize a rubber sealing surface on the disc and a relatively hard seating surface on the body. The disc is to be installed concentrically inside the va1ve within +/- 0.010 inch. Concentricity adjustments are performed by the manufacturer in the factory prior to shipment to PVNGS. The concentricity is axially adjustable utilizing a thrust bearing stud which screws into the lower valve shaft (Figure 1). After the proper gap adjustments are made, the thrust bearing stud is pinned through the valve shaft utilizing a spiral pin. The spiral pin material specified by the manufacturer for the thrust bearing stud is AISI 420 stainless steel.
Following the containment purge valve te'st failures, APS engineering personnel (utility and non-utility, non-licensed) initiated a root cause investigation. The valves were disassembled and it was discovered that, both valve discs had moved axially resulting in out of specification top and bottom gaps between the seat and disc. Further investigation revealed that the spiral pins affixing the thrust bearing studs in place had failed allowing the thrust bearing studs to turn.
The failed spiral pins were examined and discovered to have failed as a result of intergranular fracture, most probably the result of hydrogen embrittlement. Based upon this information, it was concluded on October 26, 1989, that a single cause resulted in both failures which constituted a reportable condition pursuant to 10CFR50.73.
Following the discovery that a single cause had resulted in both Unit 3 valve malfunctions, an investigation was initiated to determine if a problem existed in other PVNGS containment purge valves. Since Unit 2 was in a mode which required that the containment purge valves be operable, and since the valves could not be disassembled for inspection, local leak rate testing was satisfactorily performed to verify that the Unit 2 valves would continue to function properly. Additionally, the valves were mechanically secured in place to ensure that they do not reposition possibly resulting in an inappropriate seal.
Subsequent investigation also determined that similar conditions existed in Unit 1 containment purge valves and that AISI 420 stainless steel pins are installed in other Henry Pratt butterfly valves in the Essential Cooling Water System (BI) and the non-safety related Nuclear Cooling Water, System (CC)(See Section I.K for a listing of all valves).
NAC Form SSCA )SS9)
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NAC FOAM 356A US. NUCLEAR REGULATORY COMMISSION APPAOVEO OMB NO. 3)600)0S IBSS)
EXPIRES: S/30IQ2 ESTIMATED BUADEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION REOUESTI 60A) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT 131600104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.
FACILITYNAME u) DOCKET NUMBER 12) LEA NUMBER )6) PAGE 13)
YEAR SEQUENTIAL REVISION NUMSSR NUM SR Palo Verde Unit 1 0 s o 0 0 5 2 8 8 9 0 1 8 0 1 .0 4 OF TEXT II/moro spooo )smouurd, uso eckWondiYRC Foml 36SABI 117)
C. Status of structures, systems, or components that were inoperable at the start of the event that contributed to the event:
During the LLRT testing in Unit 3 described in Section containment purge valves were not required to be operable at the I', the time of event discovery. No other structures, systems, or components were inoperable at the start of the event which contributed to the event.
D. Cause of each component or system failure, if known:
Note: This section includes information requested by 10CFR21 concerning the nature of the defect and dates for which information was developed.
Following. the LLRT test failure for the exhaust containment purge valves on October 17, 1989, an approved work authorization document was initiated to troubleshoot the cause of the excessive leakage. Troubleshooting was performed under the supervision of APS engineering personnel. The valves which failed were the inside 42-inch containment isolation exhaust valve (I.D. No.
3JCPAUV2B) and the outside 42-inch containment isolation exhaust valve (I.D. No. 3JCPBUV3B). Both supply containment purge valves were satisfactorily tested on October 18, 1989.
The first part of troubleshooting involved checking the gaps between the disc and the body seating surface. The purpose for checking the gaps was to determine if the specified +/- 0.010 inch concentricity was maintained. It was necessary to remove the rubber seal as the seal will tend to center the valve disc as the disc is rotated into position. Valve 3JCPAUV2B was found to have a 0.188 inch larger gap at the top of the disc than at the bottom of the disc. Valve 3JCPBUV3B was found to have a 0.020 inch larger gap at the bottom of the disc than at the top of the disc.
Also inspected during this phase of troubleshooting were the parts under the bottom cover cap. These parts included the thrust collar, thrust collar pin, and thrust bearing stud. During this inspection it was observed that the thrust collar and thrust bearing stud could be rotated by hand on both valves. This indicated that one of the pins in the thrust bearing stud assembly had broken. This would explain the misalignment of the discs.
During further disassembly and troubleshooting of valve 3JCPBUV3B, engineering discovered that the thrust bearing stud spiral pin was N R C Form 366A (666)
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NRC FORM 34SA U.S. NUCLEAR REGULATORY COIrrlMISSION APPROVEO OMS NO. 31500104 ISSS)
EXP IR ESI 4)30)92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST: 608) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT 13150410e). OFFICE OF MANAGEMENTANO BUDGET, WASHINGTON, DC 20503.
FACILITY NAME Ill DOCKET NUMBER 12) LER NUMBER (5) ~ AQE LS)
II5 V Ie IO N YEAR pYg SEQUENTIAL c~P'UMeell NUMeeII Palo Verde Unit 1 o s o o o 5 28 89 0 1 801 05 OF 1" 2 TExT IIImare eaece le er)aurNL Iree RFI)arM)HRc FarIII 30)AB) I)7) fragmented in approximately four large and many smaller jagged edge pieces. The thrust collar pin was undamaged. Magnified pictures of the failed pin surfaces revealed jagged intergranular breaks. There were no obvious breaks in the areas of the shear planes. The pieces were provided to an APS metallurgist (utility, non-licensed) for evaluation. The pieces were also sent to a
,certified metallurgical test facility, Metals Engineering Testing Labs (METL), for determination of failure mode.
Next, an approved work authorization document was issued to troubleshoot and inspect the other containment purge valve which had exhibited excessive leakage (valve no. 3JCPAUV2B). The valve was disassembled and it was noted that the thrust bearing stud could be rotated by hand. Further inspection of the thrust bearing stud pin revealed failure of a similar but more extensive nature than observed in valve 3JCPBUV3B. Approximately 30 small jagged pieces were found. The thrust collar and the thrust collar pin were not damaged. The bearing and its outer race exhibited minor signs of oxidation possibly due to the presence of water.
The oxidation itself is not significant; however, the presence of water is significant from a metallurgical standpoint in that hydrogen embrittlement would a viable cause of failure.
The examination results from METL were received on October 26, 1989, and indicated that the failure mode was intergranular fracture, most probably caused by hydrogen embrittlement. An APS metallurgist inspection of the failed pin has determined that the pin was not brittle when it was originally installed. This is based on the fact that the end of the pin exhibited signs of mushrooming where it was hammered into place during installation.
This indicates that the pin had acceptable ductile qualities when installed. APS believes that if the intergranular fracture was caused due to improper heat treating, the pin would have shattered during installation and would not have mushroomed on the end of the pin.
In conclusion, APS has determined that the root cause of failure is most likely due to'hydrogen embrittlement of the thrust bearing stud spiral pins. The spiral pins were manufactured from a susceptible material and indication that moisture 'had been present was observed.
I NRC F onII 3554 I EBS)
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NAC FORM344A UA. NUCLEAR REQULATOAYCOI4MISSION APPROVED OMB NO,3)504))04 ISSS)
EXPIRES: 4/30/02 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT {LERI INFORMATION COLLECTION REQUEST: 500 HAS. FORWARD COMMENTS REQARDINQ BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAQEMENT BRANCH (P430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINQTON, DC 20555, AND TO THE PAPERWORK REDUCTION PAOSECT 13)504)104). OFFICE OF MANAQEMENTAND BUOQET,WASH)NOTCH,OC20503.
FACILI'TY NAME Il) DOCKET NUMBER 12) LER NUMBER (SI ~ AQE 13)
YEAR /~I SEQUENTIAL REVISION
.l..l NUM ER NSr NUN ER Palo Verde Unit 1 0 5 o o o 52 889 0 1 8 0 1 0 OF TEXT /I/m<<e W>>co /4 Nr)o/44L Ulo oIAFo'<<>>/HRC Arm 35543/ (IT)
Failure mode, mechanism, and effect of each failed component, if known:
The inability to meet LLRT acceptance criteria was caused by axial valve disc misalignment. The valve disc misalignment resulted from the thrust bearing stud spiral pin failure. The pin failure allowed the thrust bearing stud and thrust collar assembly to rotate during valve operation. The free rotation allowed the thrust bearing stud to screw into or out of the lower valve shaft.
For failures of components with multiple functions, list of systems or secondary functions that were also affected:
The containment purge valves do not have multiple functions.
However, subsequent review has determined that AISI 420 stainless steel pins are also installed in valves in the Essential Cooling Water System (BI) and the Nuclear Cooling Water System (CC).
For failures that rendered a train of a safety system inoperable, estimated time elapsed from the discovery of the failure until the trains were returned to service:
The inability to meet LLRT acceptance criteria in the Unit 3 exhaust containment purge valves did"not render a train of a safety system inoperable as the containment purge valves were not required to be operable at the time of event discovery.
H. Method of discovery of each component or system failure or procedural error:
The failed spiral pins in the containment purge exhaust valves were discovered by APS engineering personnel during the investigation to determine the cause of the valves not meeting LLRT acceptance criteria as discussed in Section I.B and I.D.
There were no procedural errors.
Cause of Event:
The cause of this event is described in Section I.D.
Safety System Response:
Not applicable - there were no safety system responses and none N Ac Foml 344A ISSB)
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NRC FORM344A U.S. NUCLEAR REOULATORY COliIMISSION APPROVEO 0MB NO. 3)504(04 (449)
EXPIRES: tU30)92 ESTIMATED BURDEN PEA RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION REOUESTI 500 HAS. FORWARD COMMENTS REOARDINO BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAOEMENT BRANCH IP430), U.S. NUCLEAR REOULATOAY COMMISSION, WASHINOTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT 1315041041. OFFICE OF MANAGEMENTAND BUDOET,WASHINOTON, DC 20503.
FACILITY NAME (ll DOCKET NUMBER (2) LEA NUMBER (4) PACE (3)
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/gal'lvlslon ttvM Sn Palo Verde Unit 1 o 6 o o 0 5 28 89 018 0 1 0 70F1, 2 TEXT N moto i>>co Jt otnt4otE,I>>o rdrNonVHRC Fcnn 34443) (17) were necessary.
Failed Component Information:
Note: This section includes information requested by 10CFR21 concerning the identification of the firm supplying the basic component and the number and location of the valves at Palo Verde The containment purge valves discussed above are supplied by the Henry Pratt Company. They are 42-inch Series 1200 butterfly valves. The same valves are installed in Units 1, 2, and 3.
Additionally, APS has performed a review of other Henry Pratt butterfly valves being used at PVNGS in safety relat(;d applications which use an AISI 420 stainless steel pin to secure the thrust collar or thrust bearing stud. Based upon this review, it was determined that the following valves in Units 1, 2, and 3 may be susceptible to the same failure mode:
Valve Valve size ~Sstem* Model No.
J EWAHCV067 lpn EW Series 1100 JEWAHCV133 lpn EW Series 1100 J EWAHCV134 lpn EW Series 1100 JEWBHC0068 lpn EW Series 1100 JNCAHCB258 lpn NC Series 1100 JNCAHCV244 I Q ll NC ~ Series 1100 JNCHCV0259 1Qtt NC Series 1100 JNCBHCV245 ]Qn NC Series 1100 JEWAHCV005 2Qtt EW Series 1100 JEWAHCV041 2pn EW Series 1100 JEWAHCV053 2Qtt EW Series 1100 JEWBHCV006 2pn EW Series 1100 JEWBHCV042 2pn EW Series 1100 JEWBHCV054 2pn EW Series 1100 JEWBHCV136 20" EW . Series 1100 JEWAHCV135 20" EW Series 1100 JEWAUV0065 14 tt EW Series 1100 JEWAUV0145 ] 4tt EW Series 1100 JEWBHCV066 ] 4tt EW Series 1100 JEWBHCV146 14tt 'W Series 1100 JEWAHCV071 3Qtt EW Series 1100 JEWBHCV072 30" EW Series 1100 JNCBUV0401 ]pn NC Series 1100 JNCAUV0402 lpn NC Series 1100 JNCBUV0403 ]pn NC Series 1100 NAC F onm 355A (549)
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NRC FORMSSSA ILS. NUCLEAR REGULATORY COMMISSION APPROVEO OMB NO. 31504104 (559)
EXPIRESI 4/30/92 ESTIMATFD BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT {LER) INFORMATION COLLECTION REQUEST: 50/I HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20SSS, AND TO THE PAPERWORK REDUCTION PROJECT (3160410(I. OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON,OC 20503.
FACILITYNAME (11 DOCKET NUMBER (2I LER NUMBER (Sl PAGE (31 YEAR '.p+ SSOVSNTIAL NVMOER ..
ggj IIEVISI04 NVMOSII Palo Verde Unit 1 o s o o o 52 889 01 8 0 1 08 oF 1 2 TEXT //fmoro <<Moo /T adorelPIE INo rc I/ioorM/HRC forrrr 3SSAB/(IT(
Valve Valve size ~Sstem+ ~odel No
, JCPAUV002A 42" CP Series 1200 JCPAUV002B 42 II CP Series 1200 JCPBUV003A 42 II CP Series 1200 JCPBUV003B 42" CP Series 1200 JCPAUV004A 8 II CP Series 1200 JCPAUV004B 8 II CP Series 1200 JCPBUV005A 8 II CP Series 1200 JCPBUV005B 8 II CP Series 1200
- EW - Essential Cooling Water System NC - Nuclear Cooling Water System CP - Containment Purge System Further information concerning the number and location of valves supplied to other facilities wieh AISI 420 stainless steel pins in a susceptibl'e environment should be obtained from the Henry Prate Company.
II. ASSESSMENT OF THE SAFETY CONSEQUENCES AND IMPLICATIONS OF THIS EVENT Note: This section contains the information requested by 10CFR21 concerning the nature of the safety hazard which is created or could be create.
The 42-inch containment purge isolation valves are required to be closed during plant operation since these valves have not been demonstrated eo be capable of closing during a Loss of Coolant Accident (LOCA) or steam line break accident. Maintaining these valves closed during plant operations ensures that excessive quantities of radioactive materials will not be released via the containment purge system. To provide assurance that the 42-inch valves cannot be inadvertently opened during operation, ehey are locked closed and electrical power is isolated from the valve operator. Additionally, the 42-inch valves are leak checked following a refueling outage after securing them in the closed position.
Use of the containment purge lines is restriceed to 'the 8-inch purge isolation valves during plant operations since, unlike the 42-inch valves, the 8-inch valves will close during a LOCA or steam line break accidene.
The 42-inch containment refueling purge valves, the 8-inch'containmene power access purge valves, and the 10-inch Nuclear Cooling Water System valves 9NCAUV-401, 402, 403) that are listed in Section IeK are pare of
>NRC form 365A W!9)
NRC FORM 3SSA US. NUCLEAR REGULATORY COIIUr(ISSION (BSQ) APPROVED OMB NO.31500)OS EXPIRESI E/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENTBRANCH (F430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500)OS). OFFICE OF MANAGEMFNTAND BUDGET, WASHINGTON, DC 20503.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (5) PAGE 13) mg'EQUENTIAL .@j VISIO YEAR NUMBER r, R NUMSER Palo Verde Unit 1 o s o o o 5 2 8 8 9 01 8 01 0 9 QF 1 2 TEXT ///moro tpoco It roEM)RE Irto oti/i'cnol HRC Forrrr 3/ISA't/ (IT) the containment pressure boundary. As such, these valves must remain sealed when closed to limit the off site dosage below the requirements of 10CFR100.
APS has shown that failure of the thrust bearing stud pin causes misalignment and subsequent leakage of the containment refueling purge valves. APS has not determined if this leakage would increase or valves would continue to operate and perform their intended safety if the function during or after a postulated accident (i.e., Design Basis Earthquake) with a broken thrust bearing stud pin. Tt is therefore assumed that failure of the thrust collar stud pin in the containment
.refueling purge valve could result in misalignment during a postulated accident and subsequent radiological release in excess of the limits in 10CFR100.
Nuclear Cooling water valves JNCHCV-244, 245, 258 and 259 and Essential Cooling Water System (EW) valves JEWHCV-67, 68, 133 and 134 isolate the Nuclear Cooling Water System (NC) from fuel pool heat exchangers (DA)(HX) to allow for cooling of the heat exchangers with essential cooling water when the Nuclear Cooling Water is not available. The NC valves are normally open and must be manually closed to allow for cooling of the fuel pool heat exchangers with essential cooling water.
The EW valves are normally closed and must be manually opened to allow essential cooling water into the Nuclear Cooling Water System. Six of the twenty-four pins removed from valves in the NC and EW systems in Units 1, 2, and 3 were found to have minor cracks. The remaining pins were normal.
APS has not determined if the preceding NC and EW valves could perform their intended safety function in conjunction with a broken pin. It is therefore assumed that failure of the thrust collar pin in valves JNCHCV-244, 245, 258, 259 and Essential Cooling Water System valves JEWHCV-67, 68, 133 and 134 would not allow sufficient cooling water to be delivered to the fuel pool heat exchangers and could result in a subsequent radiological reiease in excess of the limits of 10CFR100.
Essential Cooling Water valves JEW-65, 145 and JEWHCV-66, 146 are cross tie isolation valves between the Nuclear Cooling Water System and the Essential Cooling Water System. The cross tie isolations are used to provide cooling water to the non-safety related equipment that are normally fed by the Nuclear Cooling Water System such as the Reactor Coolant Pumps (AB)(P), Control Element Drive Mechanism cooling coils (CD), and Nuclear Sampling System heat exchangers (HX) when the nuclear cooling water is not available. APS has not determined if the valves would perform their intended safety function during a postulated NRC Form 3EEA (BS9)
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NAC FORMSSSA US. NUCLEAR REGULATORY COMMISSION APPROVED OMS NO.31600)04 (660)
EXPIRES: e/30/02 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFOAMATION COLLECTION REOUESTI 500 HRS. FORWARD COMMENTS REGARDING SUADEN ESTIMATE TO THE RECORDS CONTINUATION 'EXT AND REPORTS MANAGEMENT SAANCH IP430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, ANO TO THE PAPERWORK REDUCTION PROJECT 13150010O), OFFICE OF MANAGEMENTAND SUDGET, WASHINGTON, DC 20503.
FACILITY NAME I'l DOCKET NUMSER Ill LER NUMSEA IS) ~ AGE IS)
YEAR SEGUENTIAL .~oo REVISION NUM ER NUMSEA Palo Verde Unit TEXT ///IINee epeoe /s tapked,,IIae ~ 1 HRC Foml 35SA 3 / OT) accident in conjunction with a broken pin.
o s o o o 52 889 It 0 1 801 10 is therefore assumed that OF 1 2 failure of the valves JEWUV-65, 145 and JEWHCV-66, 146 could cause the Essential Cooling Water System to loose inventory which in turn 'could lead to a postulated radiological release in excess of 10CFR100 limits.
It should be noted that, while the safety consequences and implications of the spiral pin failures is indeterminate and thus reportability pursuant to 10CFR21 is indeterminate, this'eport is being submitted in accordance with the provisions of 10CFR21 due to the potential generic safety implications.
III. CORRECTIVE ACTIONS:
This section contains the information requested by 10CFR21 concerning the corrective action which has been, is being, and will be taken; the organizations responsible for the corrective action; and the length of time for accomplishing the corrective action.
A. Immediate In Unit 2, the 42-inch containment purge valves were satisfactorily local leak rate tested and then mechanically secured in the closed position pending replacement of the pins during the next refueling outage.
B. Action to Prevent Recurrence:
In Units 1, 2, and 3 the spiral pins have been replaced in the valves listed below with suitable replacement pins (302 stainless steel).
Valve No ~Setem Function JNCBUV0401 NC Containment Isolation JNCBUV0402 NC Containment Isolation JNCVUV0403 NC Containment Isolation JNCAHCV244 NC NC-PC* System Isolation JNCBHCV245 NC NC-'PC* System Isolation JNCAHCB258 NC NC-PC* System Isolation JNCHCV0259 NC NC-PC* Syst: em Isolation JEWAUV0065 EW NC-EW Cross Tie Isolation JEWBHCV066 EW NC-EW Cross Tie Isolation JEWAHCV067 EW NC-EW Cross Tie Isolation JEWBHC0068 EW NC-EW Cross Tie Isolation JEWAHCV133 EW NC-EW Cross Tie Isolation NRC FomI 355A 1600)
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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6 J)9) APPROVED OMB NO. 3(604)104 E XP I R ES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUESTI 60/) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP4)30). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20666, AND TO THE PAPERWORK REDUCTION PROJECT (31604)104). OFFICE OF MANAGEMENTANO BUDGET,WASHINGTON, OC 20603.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)
YEAR SEQUENTIAL IISVISION II VMS 6 Il NUMSSII Palo Verde Unit 1 5 28 89 0 1 8 0 1 1 1 or- 1 2 TEXT ///moro Sooco/4 ror)rrirod, Iron oddr)r)rrM//VRC Farm 3664'sl (IT)
Valve No ~So~co ~Func lon JEWAHCV134 EW NC-EW Cross Tie Isolation JEWAUV0145 EW NC-EW Cross Tie Isolation JEWBHCV146 EW NC-EW Cross Tie Isolation JCPAUV004A CP 8-Inch Purge Isolation JCPAUV004B CP 8-Inch Purge Isolation JCPBUV005A CP 8-Inch Purge Isolation JCPBUV005B CP 8-Inch Purge Isolation
- PC-Spent Fuel Pool Cooling System (DA)
The 42-inch containment purge valve spiral pins have been replaced in Units 1 and 3. The 42-inch containment purge valve spiral pins will be replaced in Unit 2 prior to restart from their next refueling outage.
The remaining Henry Pratt valves listed in Section IeK with AISI 420 stainless steel pins do not perform a function necessary for the operation of their system. An engineering evaluation providing technical justification for not replacing the pins has been prepared.
APS will contact other valye manufacturers to identify any subcomponent which is manufactured "from materials with high Rockwell hardness that could be susceptible to hydrogen embrittlement. Based upon the results of this investigation, appropriate corrective action will be developed and implemented.
A schedule for accomplishing this activity is planned to be developed by March 15, 1990.
IV. PREVIOUS SIMILAR EVENTS:
There have been no previous similar events reported pursuant to 10CFR50.73.
NRC Form 366A (64)9)
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NAC FOAM 355A U.S. NUCLEAR REGVLATORY COMMISSION
.16401 APPROVEO OMB NO. 31500104 EXPIRES: 4/30/02 ESTIMATEO BUROEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARO COMMENTS RECAROING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATlON ANO REPORTS MANAGEMENT BRANCH (P.5301, V.S. NUCLEAR AEGULATOAYCOMMISSION, WASHINCTON. OC 20555. ANO TO THE PAPERWORK REOVCTION PROJECT (3(5001041. OFFICE OI'ANAGEMENTANO BUOGET,WASHINGTON,OC 20503.
FACILITY NAME (11 COCKET NUMBER (21 LER NUMBER 151 PACE (31 YEAR 4CC SEQUENTIAL ~'/i REVISION NUMssrl ~ IUMSSR Palo Verde Unit 1 o 6 o o o 5 28 89 018 0 1 1 2 OF 1 2 TEXT al mare Specs is reeuired, I/se sddrdaos/HRC fo/m 3654'sl (17)
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