05000293/LER-1995-001, :on 950101,found That Air Operated Valve in B Vacuum Relief Sys Opened Due to Loose Fuse in Control Circuirty for Solenoid Valve That Controls Air to Air Operated Valve.New Fuse Installed
| ML20078J262 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 01/30/1995 |
| From: | Boulette E, Calfa J BOSTON EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 95-008, 95-8, LER-95-001, LER-95-1, NUDOCS 9502070364 | |
| Download: ML20078J262 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(x) |
| 2931995001R00 - NRC Website | |
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._
y BOSTON EDISON Pilgrim Nuclear Power Station 10 CFR 50.73 Rocky Hill Road Plymouth, Massachusetts 02360 E. T. Boulette, PhD January 30, 1995 S&nior Vice President-Nuclear BEco Ltr. 95408 l
U.S. Nuclear Regulatory Connission i
Attn: Document Control Desk Washington, D.C. 20555 Docket No. 50-293 License No. DPR-35 The enclosed Licensee Event Report (LER) 95-001-00, " Reactor Building-i.o-Torus Train
'B' Vacuum Relief System Actuation While Operating", is submitted in accordance with 10 CFR Part 50.73.
Please do not hesitate to contact me if there are any questions regarding this
- report, dWhM E. T. Boulette, PhD JPC/nas
Enclosure:
LER 95-001-00 cc:
Mr. Thomas T. Martin Regional Administrator, Region I U.S. Nuclear Regulatcry Commission 475 Allendale Rd.
King of Prussia, PA 19406 Sr. NRC Resident Inspector - Pilgrim Station Standard BECo LER Distribution 9502070364 950130 PDR ADOCK 05000293 s
PDR l
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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 n-m EXPIRES 5/31/95 l
ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS LICENSEE EVENT REPORT (LER)
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C AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR i
REGULA10RY COMMISSION, WASHINGTON. DC 20S55 0001, AND j
TO THE PAPERWORK REDUCTION PROJECT (3150-0104). OFFICE l
(see reverse for rwrnber of digns/ characters for each block)
OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503
(
FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
PILGRIM NUCLEAR POWER STATION 05000 -293 1 of 5 TITLE (4)
Re:ctor Building-to-Torus Train 'B' Vacuum Relief System Actuation While Operating EVENT DATE (5)
LER NUMBER (6)
REPOR ' ATE (7)
OTHER FACILITIES INv0LVED (8)
SEQUENTIAL REVISION F ACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR N/A 05000 FACUTY NAME DOCKET NUMBER 01 01 95 95 001 00 01 30 95 N/A 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMEMS OF 10 CFR S: (Check one or more)(11)
MODE @)
N 20.402(b) 20.405(c)
X 50.73(a)(2)(iv) ' ~
73 71(b) 20Mam 50.36fcW Sa73(aM2M 73 M c)
LEvE 10) 100 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) kTRC 20.405(a)(1)tM
$0.73(alf2)(ii) 50.73(a)(2)(viii)(B) 20.405(a)(1)(v) 50 73(a)(2)(iii) 50.73(a)(2)(x)
Form 366Al LICENSEE CONTACT FOR THIS LER (12)
NAME TELEPHONE NUMBER (include Area Code)
Jefffrey P. Calfa, Senior Compliance Engineer (508) 830-8108 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
CAUSE
SYSTEM COMPONENT MANUFACTURER
CAUSE
SYSTEM COMPONENT MANUF ACTURER B
BF FUB B130 N
SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED pe y.S., compieie EXPECTED SUBMISSION DATE, YE X
NO SUBMISSION DATE (15)
ABSTRACT (Umit to 1400 spaces, i e., approxirt.dely 15 single-spaced typewritten lines)(16)
On January 1,1995, at approximately 2330 hours0.027 days <br />0.647 hours <br />0.00385 weeks <br />8.86565e-4 months <br />, the control room indicators for the Reactor Building-to-Torus Train
'B Vacuum Relief System were found to not be illuminated during performance of a daily surveillance.
Investigation found that the air operated valve in the 'B' Vacuum Relief System had opened. Moreover, there was no indication that the in-series check valve had opened. Therefore, no vacuum relief function occurred.
The cause of the opening of the air operated vacuum relief valve was a loose fuse in the control circuitry for the solenoid valve that controls air to the air operated valve.
The fuse clip tension became loose, creating a loss of circuit continuity across the fuse.
Immediate corrective actions involved replacement of the fuse and tightening of the fuse clip tension.
Inspection of other panels in the Control Room and Cable Spreading Room identified no loose or oxidized fuses in those panels. Additional corrective action will include a more detailed inspection of other fuse clips and corrective maintenance of other fuse clips for any application found loose within the same panel as the fuse for the vacuum relief valve. A procedure revision will be made to require inspection of fuses and their holders whenever fuses are removed during performance of a temporary procedure.
The event occurred with the plant operating at 100 percent power with the reactor mode selector switch in the RUN position.
The Reactor Vessel pressure was 1037 psig with reactor vessel water temperature at saturation temperature for the reactor pressure.
This report is submitted in accordance with 10 CFR 50.73(a)(2)(iv).
This event posed no threat to public health and safety.
NRCFonM3 Ars.a
NRC FORM.366A U.S. NUCLEAR REGULATORY COMMISSION APPIOVED BY OMB NO. 3150-0104 4 5-On EXPlRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WirH THIS LICENSEE EVENT REPORT (LER) l"!%"^# 6' m"'Jnu"rJfEJ' JJf0 OiN =
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DOCKET NUMBER (2)
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PAGE (3)
"P UMW"R YEAR E
PILGRIM NUCLEAR POWER STATION 05000-293 U
95
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TEXT (if more space es required, use additional copies of NRC Forrn 366A)(17)
BACKGROUND The safety objective of the Primary Containment System (PCS) is to provide the capability, in conjunction with other safeguard features to limit the release of fission products in the event of a design basis accident so that offsite doses would not exceed the guidelines set forth in 10 CFR 100. The PCS design employs a low leakage pressure suppression containment system which houses the Reactor Vessel, the Reactor Recirculation System loops and other connections of the Reactor Primary System.
The Venting and Vacuum Relief System is part of the PCS design. The purpose is to equalize the pressure between the Drywell and Suppression Chamber and the Reactor Building so that the structural integrity of the containment is maintained.
The vacuum relief system from the Reactor Building to the Suppression Chamber (i.e., Torus) consists of two 100 percent vacuum relief trains with two valves in series. Operation of either train will maintain the pressure differential to less than 2.0 psig (i.e., the external design pressure). Train 'B' consists of air operated valve A0-50408 and in-series passive check valve X-212B.
The controls and air supply for A0-5040A/B are similar but separate from each other.
The actuator of each air-operated valve, normally maintained in the closed position by pressurized air, is spring loaded to open for vacuum relief. The actuator spring opens the valve if air pressure supplied to the actuator decreases to a pressure within the range 30 to 35 psig.
Pressure switch PISD-50408 senses the differential pressure between the Torus atmosphere and the atmosphere within the Reactor Building. The pressure switch or the manual control switch in the Control Room on Panel C-7 functions to de-energize solenoid operated valve SV-50408, thereby venting the air pressure from the A0-5040B actuator and results in the opening A0-5040B. The power for operation of SV-50408 and indication for A0-50408 and X-2128 is supplied from 125 VDC Bus D5 through two 5 amp fuses and the in-series pressure switch and manual control switch.
The manual control switch for A0-5040B was replaced via Plant Design Change (PDC) 92-57,
" Panel C7 - Redesign" on September 30, 1994.
Post work testing was accomplished by performance of Temporary Procedure (TP)94-002, " Pre-Operational Test of Control Switches SV-5040A/CS and SV-5040B/CS at Panel C7 (PDC 92-57)" on October 3, 1994.
EVENT DESCRIPTION
On January 1, 1995, at approxigtely 2330 hours0.027 days <br />0.647 hours <br />0.00385 weeks <br />8.86565e-4 months <br />, a utility licensed operator observed there was no indication for A0-b040B and X-2128 at Panel C-7 in the Control Room. The licensed operator was per'orming surveillance procedure 2.1.15, " Daily Surveillance Log, Tech Specs & Regulatory Agencies".
Control Room personnel issued Maintenance Request (MR) 19500004.
Instrument and Control (I&C) personnel investigated and found one of the 5 amp fuses which supplies power to SV-5040B to be loose in its fuse clip. The fuse was emoved and tension was increased on the fuse clip.
I&C personnel replaced the fuse, verified the indication for A0-5040B and X-212B operated and verified that A0-5040B closed.
X-2128 remained closed throughout as a slightly positive relative pressure existed inside the torus atmosphere and not the negative relative pressure required to open the in-series, passive check valve X-2128.
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- - U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 a
t s-m EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTTH THIS LICENSEE EVENT REPORT (LER) l"f*"Of" A"n %iu'ns EU.MoL%*2 TEXT CONTINUATION
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FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
"I$IEn" UMs'?"n vtan PILGRIM NUCLEAR POWER STATION 05000-293 U
95
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TEXT (It more space as required, use add #tional copies of NRC Form 366A)(17)
Operations personnel wrote Problem Report (PR) 95.9002 to document the discovery.
The NRC Operations Center was notified in accordance with 10 CFR 50.72 at 0310 hours0.00359 days <br />0.0861 hours <br />5.125661e-4 weeks <br />1.17955e-4 months <br /> on January 2, 1995.
The event occurred while operating at 100 percent power with the reactor mode selector stsitch in the RUN position.
The reactor pressure was 1037 psig with reactor vessel water temperature at saturation temperature for the reactor pressure.
CAUSE
The cause of the actuation of A0-5040B was a loose fuse in the control circuit which caused solenoid 5V-5040B to de-energize. The valve opened during the shift prior to the surveillance as the surveillance is performed once per shift. The fuse clip which normally holds the fuse in place had apparently loosened upon fuse removal during the performance of TP94-002 on October 3, 1994.
The fuse was found to be coated with a layer of oxidation product and fuse removal apparently resulted in a slightly reduced tension in the fuse clip.
Eventually the contact of the fuse in the clip decreased enough to cause a loss of power to solenoid valve SV-50408.
Engineers inspected Panel C-7 and found additional fuses also coated with a layer of oxidation.
There was no indication that these fuses were loose, inspection of other panels in the Control Room and in the Cable Spreading Room did not identLify any other fuses coated with a corrosion product layer.
The condition appears to be limited to Panel C-7 due to the cartridge fuses used in the Pinel.
The cartridge fuses in C-7 are not frequently used in the plant and are apparently more susceptible to oxidation.
A contributing cause of the actuation was that TP94-002 had no requirement to inspect fuses and fuse clips upon removal and re-installation to verify good condition and proper fuse clip tension. Nuclear Organization personnel have previously recognized that fuses and their holders should be inspected upon fuse removal and re-installation. The administrative procedure governing the writing surveillance procedures is Procedure 1.3.4-1.8, " Surveillance Procedures Formatting Guide" The procedure requires that each time a fuse is removed in a surveillance procedure, the fuse and holder are inspected.
Procedure 1.4.5, "PNPS Tagging Procedure" requires an inspection of fuses and their holders when a fuse is removed under a tagout. TP94-002 was written in accordance with the procedure for writing temporary procedures 1.3.4-1.9, " Temporary and Special Test Procedures Formatting Guide".
Procedure 1.3.4-1.9 does not contain any specific instructions for including an inspection of fuses and their holders upon removal when such an activity is to be part of a temporary procedure.
CORRECTIVE ACTIOJ The fuse tension was increased on the fuse clip for the loose fuse in the control circeit for SV-5040B and a new fuse was installed under MR19500004.
Inspection of Panel C-7 identified other fuses which were coated with a oxidation product. While this oxidatibn does not impact operability, the fuses should be replaced.
Inspection of other panels within the control room and the cable spreading room identified no other loose fuses or fuses having an oxidation product layer.
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NRC FORM.366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 1
(S.92),
EXPIRES 5/31/95
)
ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS UCENSEE EVENT REPORT (LER)
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DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR B
N PILGRIM NUCLEAR P _WER STATION 05000-293 U
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TEXT (If more space is required, use additional copies of NRC Form 3%AJ (17)
Maintenance Request (MR) 19500325 has been written to perform a more comprehensive inspection of all fuses and fuse holders within Panel C-7, to replace any fuses having a layer of oxidation product and to repair any other problems encountered with fuse holders t
or clips.
Procedure 1.3.4-1.9, " Temporary and Special Test Procedures Formatting Guide", will be revised to require similar fuse inspections as already required in surveillance procedures and during system tagouts v.volving fuse removal. Additionally, changes will be made to Procedure 1.3.4-1.9 to make !t more closely follow the guidelines of Procedure 1.3.4-1.8.
TP94-002 was written to post work test PDC 92-57 and as such will be retired.
SAFETY CONSE0VENCES This event posed no threat to public health and : safety.
As a negative relative pressure did not exist in the Torus, check valve X-212B, in-series with A0-50408, remained closed and maintained the PCS barrier during the period A0-5040B was open.
Check Valve X-2128 local leak rate testing results have historically shown nearly zero leakage.
This report is submitted in accordance with 10 CFR 50.73(a)(2)(iv) because of the automatic opening of A0-50408 that is ; M of the Train 'B' Reactor Building-to-Torus atmosphere relief system.
SIMILARITY TO PREVIOUS EVENTS A review was conducted of Pilgrim Station Licensee Event Reports (LERs) submitted since January 1984.
The review focused on LERs submitted in accordance with 10 CFR 50.73(a)(2)(iv) involving the Reactor Building to Torus vacuum breakers or the Torus to Drywell vacuum breakers. The review identified LER 93-006-00.
For LER 93-006-00, with the plant shutdown on March 15, 1993, both A0-5040B and X-212B opened as a result of a negative differential pressure between the Torus atmosphere and the Reactor Building atmosphere. Torus pressure had lowered as a result of lowering Torus water level following response to a scram, and meanwhile, the Reactor Building atmospheric pressure was affected by the passing of a severe coastal storm.
Corrective action taken included the addition of nitrogen to the torus atmosphere ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) CODES The EIIS codes for this report are as follows:
NRC FC7N 366A (')42)
- U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OM8 NO. 3150-0104 i S-o2).
EXPlRES 5/31/95 ESTIMATED BUFIDEN PER RESraONSE TO COMPLY WTTH THIS LT* L' s' f" "'M"'MATUo7HiiNFO1%
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LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION ESEAN$$uis's"ENNETc"N!'rE'N*$[f[D TO THE PAPERWOFIK REDUCTION PROJECT (315041D4), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.
FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR R
MBER PILGRIM NUCLEAR POWER STATION 05000-293 U
95
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TEXT (tt more space is required, use additional copies of NRC Form 366A)(17)
COMPONENTS CODES t
Control, Differential, Pressure (PISD-50408)
PDC l
Indicator, Differential, Pressure (PISD-50408)
PD1 Relief Valve (AO-5040B, X-2128)
RV Fuse FU Fuse Block (Fuse Clip)
FUB SYSTEMS Containment Vacuum Relief System BF Containment Environmental Monitoring System IK Reactor Building NG t
NRC FORM 386A l!b-92)