05000499/LER-1993-013
| ML20056E219 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 08/17/1993 |
| From: | Groth J, Pinzon J HOUSTON LIGHTING & POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LER-93-013-01, LER-93-13-1, ST-HL-AE-4546, NUDOCS 9308200303 | |
| Download: ML20056E219 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| 4992093013R00 - NRC Website | |
text
t The Light c o mp a n y ut h Texas Project Electric Generating Station P. O. Box 289 Wadsworth, Texas 77483 Houston Lighting & Power August 17, 1993 ST-HL-AE-4546 File No.: G26 10CFR50.73 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Unit 2 ;
Docket No. STN 50-499 Licensee Event Report 93-013 Inadvertent ESF Actuation due to a Component Cooling Water Pump Start Durina a Maintenance Work Activity Pursuant to 10CFR50.73, Houston Lighting & Power (HL&P) submits the attached Unit 2 Licensee Event Report 93-013 regarding an inadvertent Engineered Safety Features (ESP) actuation due to a Component Cooling Water (CCW) pump start during a maintenance work activity. This event did not have an adverse effect on the health and safety of the public. ,
If you should have any questions on this matter, please contact Mr. J. M. Pinzon at (512) 972-8027 or me at (512) 972-8664.
_ ,J.E 6 J. F. Groth Vice President, .
Nuclear Generation !
i JMP/pa
Attachment:
LER 93-013 (South Texas, Unit 2) i i
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L93013RO.U2 '/ g / _;
Project Manager on Behalf of the Participants in the South Texas Project /
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9308200303 930817 2 / )(f l PDR ADOCK 05000499 ;'
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I Houston Lighting & Power Company ST-HL-AE-4546 South Te,xas Project Electrk Generating Station File No.:G26 Page 2 l
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Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission Associate General Counsel i 611 Ryan Plaza Drive, Suite 400 Houston Lighting & Power Company i Arlington, TX 76011 P. O. Box 61867 I Houston, TX 77208 Lawrence E. Kokajko 2 Project Manager Institute of Nuclear Power-U.S. Nuclear Regulatory Commission Operations - Records Center Washington, DC 20555 13H15 700 Galleria Parkway David P. Loveless Sr. Resident Inspector c/o U. S. Nuclear Regulatory Dr. Joseph M. Hendrie Commission 50 Bellport Lane P. O. Box 910 Bellport, NY 11713 Bay City, TX 77404-910 D. K. Lacker .
J. R. Newman, Esquire Bureau of Radiation Control Newman & Holtzinger, P.C., STE 1000 Texas Department of Health 1615 L Street, N.W. 1100 West 49th Street ,
Washington, DC 20036 Austin, TX 78756-3189 D. E. Ward /T. M. Puckett U.S. Nuclear Regulatory Comm.
. Central Power and Light Company Attn: Document Control Desk P. O. Box 2121 Washington, D.C. 20555 1 Corpus Christi, TX 78403 J. C. Lanier/M. B. Lee City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704 l i
K. J. Fiedler/M. T. Hardt I City Public Service P. O. Box 1771 ;
San Antonio, TX 78296 I I
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L93013RO.U2 l 1
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CTtC FORM 366 U.S. NUCLEAR aE(alLATORY COMMISSION QPP30VED BY OMB No. 3150-01G4 (5-92) EXPIRES 5/31/95 EsflMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLiCil0N REQUEST: 50.0 HRS.
LICENSEE EVENT REPORT (LER) FORWARD COMMENTS REGARD!WG BURDEN ESilMATE 10
- THE INFORMATION AND RECORDS MAhAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, (See reverse for required number of digits / characters for each block) WASHINGTON, DC 20555-0001, AND TO THE FAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET. WASHINGTON. DC 20503.
IEblLITYNAME(1) DOCKET NUMBER (2) PAGE (3)
South Texas, Unit 2 05000 499 1 OF 4 TITLE (4) Inadvertent ESF Actuation due to a Component Cooling Water Pump Start nuring a Maintnnance Work Activity EVENT DATE (5) LER NWBFR (6) REPORT DATE (7) OTHER FAClllTIES INVDlVFD (8)
MaciTH DAY YEAR YEAR MONTH DAY YEAR NUMBER NUMBER 05000 FA CKET "
07 19 93 93 -- 013 -- 00 08 17 93 O 0O OPERAllNG THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR f: (Check one or more) (11) p' g MODE (9) 20.402(b) 20.405(c) X 50.73(a)(2)(iv) 73.71(b) pcy,gg 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)
LEVEL (10) 20.405(a)(1)(li) 50.36(c)(2) 50.73( e)(2)(vi i ) OTHER 20.405(a)(1)(iii) 50.73(a)(2)(i) 50.73(e)(2)(vi i i )( A) (Specif y in 20.405(a)(1)(tv) 50. 73( a)(2)( i i ) 50.73(a)(2)(viii)(B) Abst act low 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) ARC Form 366A) t!CENSFE CONTACT FOR THIS LER (17)
NAME TELEPH0kE NUMBER (include Area Code)
Jairo Pinzon - Senior Engineer (512) 972 - 8027 CmPLETE ONE LINF FOR EACH COMPONENT F AlltJRE DESCRIBFD IN THIS REPORT (13)
CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER [
l SUPPLEMENT AL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR i YES (If yes, co m lete EXPECTED SUE. MIS $10N DATE). K NO (5
ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)
On July 19, 1993, at 2044 hours0.0237 days <br />0.568 hours <br />0.00338 weeks <br />7.77742e-4 months <br />, Unit 2 was defueled in a refueling outage.
The "B" train (2B) Component Cooling Water (CCW) pump received an automatic actuation from the non-nuclear supply header low pressure signal. The low header pressure was caused when a Motor Operated Valve (MOV-0235) was
, opened to equalize pressure across the valve. Due to a downstream valve, MOV-0236, being closed and indications that the piping in between the valves had been filled, it was assumed that a low header pressure condition would not occur. When the valve was opened, the CCW pump auto started and the operator stationed at the valve reported flow noises. The causes of this event were attributed to less than adequate plant impact review by the
, Unit Supervisor, seat leakage past MOV-0236 and untimely implementation of a recommended action from previous events. Corrective actions include repairing MOV-0236, placing a time delay in the CCW pump automatic starting circuit, and revising the guidance for control of the CCW pump mode selector switch, u t FORM 3o6 (5- G ~
Nat Fora 366A u.s. c11 CLEAR REGULATO7 COMMISSIO APPROVED EY (MB No. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BtCDEN PEtt RE$PONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.
FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE LICENSEE EVENT REPORT (LER) INFORMATION AND RECORDS MANAGEMENT BRANCH (MNB8 TEXT CONTINUATION 7714), U.S. NUCLEAR REGULATORY COMMISSION, ,
WASHINGTON, DC 20555-0001 AND TO THE PAPERWORK '
REDUCTION PROJECT (31$0-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.
FACILITY NAME (1) DOCKET NUMBER (2) LER IKMBER (6h PAGE (3)
TEAR SEQUENTIAL REVISION South Texas, Unit 2 05000 499 2 OF 4 93 -- 013 -- 00 TEXT (if vere space is reauired. use additional copies of WC Form 366A) (17)
DESCRIPTION OF EVENT:
On July 19, 1993, Unit 2 was defueled in a refueling outage. At 2044 hours0.0237 days <br />0.568 hours <br />0.00338 weeks <br />7.77742e-4 months <br />, the "B" train (2B) Component Cooling Water (CCW) pump received an automatic actuation from the non-nuclear supply header low pressure signal.
Prior to the event the "A" train (2A) CCW pump was in service and the "C" train (2C) was out of service for maintenance. Maintenance had recently been completed on the non-nuclear safety (NNS) header which was drained.
Motor Operated Valves (MOVs), MOV-0235, "NNS LOADS INL ISOL" and MOV-0236,"NNS LOADS INL ISOL" (configured in series) were closed due to the NNS header not being filled and vented. These valves are normally open and close on a Safety Injcet.4 0.- signal or low CCW Surge Tank level.
Maintenance personnel requested work start permission to retorque the flange bolts to stop leakage on MOV-0235. A requirement to perform this work was to have system pressure on both sides of the valve. Operations personnel verified no other work was ongoing or Equipment Clearance Orders (ECOs) in effect that prevented them from opening MOV-0235. Control room personnel verified the downstream valve, MOV-0236, was closed and dispatched a Reactor Plant Operator (RPO) to ensure that the vent valve in between the MOVs was closed and that MOV-0235 was ready to be opened.
Previous MOVATs testing had been performed on MOV-0235. During MOVATs testing, the valve is required to be stroked, therefore the control room i staff assumed that the header between the MOVs was filled.
The control room operator opened MOV-0235. While MOV-0235 was opening, a momentary low pressure on the CCW common header occurred resulting in CCW pump 2B starting and associated alarms annunciating in the control room.
The RPO was dispatched to the pump to ensure proper operation. Control room personnel verified conditions allowed single CCW pump operation and ,
secured CCW pump 2B. With MOV-0235 open, work commenced to retorque the ~
With MOV-0235 open, a steady decrease in CCW surge tank level was observed. After work on MOV-0235 was completed, it was closed to investigate the leak. When MOV-0235 was closed the surge tank level decrease returned to nominal. Investigation revealed that MOV-0236 was leaking by its seat.
CAUSE OF EVENT:
The cause of this ! vent was an inadequate plant impact assessment of the evolution by the Unit Supervisor and seat leakage past MOV-0236 which allowed the header to depressurize.
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i RC FORM 366A U.S. C1JCLEAR REGULATOV CtmMISSIO APPROVED BY OMB No. 3150-0104 (542) EXP!3ES 5/31/95 ESTIMATED BU3 DEN PE3 F:ESPONSE TO COMPLY WITH TH15 INFORMATION COLLECTION REQUEST: 50.0 HRS.
IS R " "
LICENSEE EVENT REPORT (LER) [og"$yE"wo REC $^ "MA[ACEMENT BRANCH MN m 4), U.S. NUCLEAR REGULATORY COMMISSION, TEXT CONTINUATION WASHINGTON, DC 20555-0001 AND T3 THE PAPERWORK REDUCTION PROJICT (31$0-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON. DC 20503.
FACitITY KAME (1) DOCKET MtMBER (2) LER KMBER (61 PAGE (3)
SEQUENTIAL REVISION YEAR N!.wEER NLwBER South Texas, Unit 2 05000 499 3@ 4 93 -- 013 -- 00 TEXT (If more space is reouired, use additional copies o# hPC Form 366A) (17)
CAUSE OF EVENT: (Cont'd)
Contributing causes were the untimely implementation of a recommendation from previous events and inconsistent guidance on the control of the CCW/ECW Mode selector switch. As a result of previous ESF actuations an ESF Task force was formed. The task force recommended that a modification to add a time delay to the low pressure CCW pump automatic start signal be made. Had this time delay been installed this unnecessary actuation may not have occurred.
ANALYSIS OF EVENT:
The unplanned actuation of an Engineered Safety Feature (ESF) is reportable pursuant to 10CFR50.73 (a) (2) (iv) . The CCW system provides cooling to support ESF functions and receives ESF actuation signals, as such. The CCW pump start was the result of a non-safety grade, non-ESF signal due to a momentary low pressure condition on the CCW common header.
Since this was a non-ESF signal no other ESF equipment changed state.
There was no adverse impact on plant or public safety as a result of this event.
STP utilizes a three position mode selector switch for each train of CCW/ECW. When selected to STANDBY, an automatic CCW/ECW pump start signal is generated on a CCW common header (non-ESF) low pressure condition or an ECW low pressure condition on 2 of 3 ECW trains. These are non-ESF signals. With the mode selector switch in OFF these signals are bypassed.
Reliability is ensured by placing one train of CCW in service and at least one additional train placed in service or in the Stand-by mode.
CORRECTIVE ACTIONS:
- 1. A Service Request was initiated to correct the seat leakage past MOV-0236. This work activity will be completed in Unit 2 prior to startup from the current outage.
- 2. Guidance for the control of the mode selector switch is being reviewed for consistency. This action will be completed by November 1, 1993.
- 3. A modification to add a time delay to the low pressure CCW pump automatic start signal will be completed for each Unit prior to startup from the current outages. It can not be proven that a time delay would have prevented this actuation; however, in coincidence with the guidance on the use of the CCW/ECW Mode selector switch, it is believed that future CCW pump auto-starts could be minimized.
The Corrective Action Process is currently under review to ensure that corrective actions are appropriately developed and implemented.
$R FORM 366A U.S. C"JCLEAR REGULATORY COpMISSIC3 APPROVED BY OMB 100. 3150-0104 (5-92) EXPIRES 5/31/95 ESilMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.
FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE LICENSEE EVENT REPORT (LER) INFORMATION AND RECORDS MANAGEMENT BRANCH (MkEB TEXT CONTINUATION 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001 AND TO THE FAPERWORK REDUCTION PROJECT (3150-0104), OFilCE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.
FACitITY EAMF (1) DOC *TY t!LMBER (2) LER WLMBER (61 PAT (3)
YEAR SEQUENTIAL REVISION
"#" "" 4 OF 4 South Texas, Unit 2 05000 499 93 -- 013 -- 00 TEXT (if note space is reouired. use additional copies of NRC Form 366A) (17)
ADDITIONAL INFORMATION:
Unplanned ESF actuation involving CCW pump starts that have been reported to the NRC within the last two years were:
o Unit 1 LER 92-005 regarding an unplanned ESF actuation of a CCW pump due to an inadequate procedure, o Unit 1 LER 92-010 regarding an inadvertent ESF actuation of a CCW pump due to a lack of procedural guidance.
o Unit 1 LER 92-015 regarding an unplanned ESF actuation of a CCW pump due to operator inattention.
o Unit 1 LER 92-016 regarding an unplanned ESF actuation of a CCW pump due to an inadequate procedure.