ML14177A532: Difference between revisions

From kanterella
Jump to navigation Jump to search
(Created page by program invented by StriderTol)
(Created page by program invented by StriderTol)
 
(2 intermediate revisions by the same user not shown)
Line 1: Line 1:
{{Adams
#REDIRECT [[05000395/LER-2014-003]]
| number = ML14177A532
| issue date = 06/24/2014
| title = LER 14-003-00 for Virgil C. Summer, Unit 1 Regarding Component Cooling System Emergency Makeup a Valve Failed to Stroke Open Rendering Train of Component Cooling Inoperable
| author name = Gatlin T D
| author affiliation = SCANA Corp, South Carolina Electric & Gas Co
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000395
| license number = NPF-012
| contact person =
| document report number = LER 14-003-00
| document type = Letter, Licensee Event Report (LER)
| page count = 4
}}
 
=Text=
{{#Wiki_filter:IThomas D. GatlinVice President, Nuclear Operations803.345.4342A SCANA COMPANY June 24, 2014Document Control DeskU. S. Nuclear Regulatory CommissionWashington, DC 20555
 
==Dear Sir I Madam:==
 
==Subject:==
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS), UNIT 1DOCKET NO. 50-395OPERATING LICENSE NO. NPF-12LICENSEE EVENT REPORT (LER 2014-003-00)COMPONENT COOLING SYSTEM EMERGENCY MAKEUP "A" VALVEFAILED TO STROKE OPEN RENDERING TRAIN OF COMPONENTCOOLING INOPERABLEAttached is Licensee Event Report (LER) 2014-003-00, for the Virgil C. SummerNuclear Station (VCSNS). This report describes the surveillance test of a normallyclosed Valve -that failed to stroke open and was therefore unable to perform its designfunction. This report is submitted in accordance with 1OCFR50.73(a)(2)(i)(B).Should.you have any-questions, please call Mr. Bruce Thompson at (803) 931-5042..Very truly yours,Thomas D. GatlinWLT/TDG/wmAttachmentc: K. B. MarshS. A. ByrneJ. B. ArchieN. S. CarnsJ. H. HamiltonJ. W. WilliamsW. M. CherryV. M. McCreeS. A. WilliamsNRC Resident InspectorQA Manager -L. W. HarrisPaulette LedbetterJ. C. MelletteEPIX CoordinatorK. M. SuttonINPO Records CenterMarsh USA, Inc.Maintenance Rule EngineerNSRCRTS (CR-14-02282)File (818.07)PRSF (RC-14-0104)Virgil C. Summer Station
* Post Office Box 88 -Jenkinsville, SC .29065 F (803) 941-9776 ONRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 0113112017(02-2014) Estmated burden per response to comply with this mandatory collection request: 80 hours.Reported lessons learned are incorporated into the licensing process and fed back to industry.Send comments regarding burden estimate to the FOIA, Privacy and Information CollectionsBranch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or byLICENSEE EVENT R (LER) internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Informaton and(See Page 2 for required number of Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC20503. If a means used to impose an information collection does not display a currently valid 0MBdigits/characters for each block) control number, the NRC may not conduct or sponsor, and a person is not required to respond to,the information collection.1. FACILITY NAME 2. DOCKET NUMBER 3. PAGEV. C. SUMMER NUCLEAR STATION, UNIT 1 05000 395 1 OF4. TITLECOMPONENT COOLING SYSTEM EMERGENCY MAKEUP "A" VALVE FAILED TO STROKE OPEN RENDERING TRAINOF COMPONENT COOLING INOPERABLE5. EVENT DATE 6. LER NUMBERMONTH DAY YEAR YEAR SEQUENTIAL REVIjNUMBER NO.04 26 2014 2014 003 -008. OTHER FACILITIES INVOLVEDDOCKET NUMBER05000DOCKET NUMBER050009. OPERATING MODE11. THIS REPORT IS SUBMITTED PURSUANT TO THE10 CFR §: (Check all that apply)D 20.2201(b) [ 20.2203(a)(3)(i) [ 50.73(a)(2)(i)(C) [ 50.73(a)(2)(vii)6 20.2201(d) [ 20.2203(a)(3)(ii) [ 50.73(a)(2)(ii)(A) [] 50.73(a)(2)(viii)(A)[] 20.2203(a)(1) [ 20.2203(a)(4) [] 50.73(a)(2)(ii)(B) [] 50.73(a)(2)(viii)(B)__ 20.2203(a)(2)(i) [ 50.36(c)(1)(i)(A) 50.73(a)(2)(iii) El 50.73(a)(2)(ix)(A)10. POWER LEVEL E] 20.2203(a)(2)(ii) [ 50.36(c)(1)(ii)(A) 50.73(a)(2)(iv)(A) [ 50.73(a)(2)(x)[] 20.2203(a)(2)(iii) [ 50.36(c)(2) 50.73(a)(2)(v)(A) .73.71(a)(4)E] 20.2203(a)(2)(iv) El 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) Fli 73.71(a)(5)0%' 20.2203(a)(2)(v) E] 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C) OTHEREl 20.2203(a)(2)(vi) [ -50.73(a)(2)(i)(B) I] 50.73(a)(2)(v)(D) Specdfy in Abstrct bel6dor in12. 'CENSENRC Form 366A12. LICENSEE CONTACT FOR THIS LERLICENSEE CONTACTBruce Thompson, Manager Nuclear LicensingTELEPHONE NUMBER (Include Area Code).(803) 931-5042D YES (if yes, complete 15. EXPECTED SUBMISSION DATE) [] NOIABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)1.0 ABSTRACTOn April 26., 2014, while performing a surveillance test, the normally closed Component Cooling (CC) System emergency makeupvalve (XVG09627A-CC) failed to stroke open. During the second attempt XVG09627A-CC opened in 11.29 seconds, which exceededthe maximum allowed stroke time often (10) seconds. This surveillance test is performed each refueling outage and was lastsuccessfully tested during the fall 2012 refueling outage (RF20). The emergency makeup supply to the CC System is provided by theService Water (SW) System. The SW System functions as a source of emergency makeup in the event of a complete loss of the normalmakeup capability provided by the Demineralized Water System or if leakage exceeds the normal makeup capacity. The safety relatedfunction of XVG09627A-CC is to open to allow SW from the "A" Train to provide makeup to the "A" train CC system. By failing toopen, this valve was unable to perform its design function without additional operator action. Since the valve did not stroke open onApril 26, 2014, the station has concluded the valve may not have operated if required during the operating cycle. WhileXVG09627A-CC was unavailable, it was determined that XVG09627B-CC was also inoperable. A PRA risk evaluation determined theevent of both valves being inoperable is of low safety significance. The cause of this event is believed to be low valve manipulationfrequency, added frictional forces, and possible spring degradation. XVG09627A-CC has been rebuilt with new closure and trip springsand new packing that has a lower friction resistance. The pressure regulator closing force was also reduced. This report is submitted inaccordance with I OCFR50.73(a)(2)(i)(B).NRC FORM 366 (02-2014)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-104 EXPIRES: 011311201702-2014) Estimated burden per response to comply with this mandatory collection request: 80 hours.Reported lessons learned are incorporated into the licensing process and fed back to industry.Send comments regarding burden estimate to the FOIA, Privacy and Information Collections* I LICENSEE EVENT REPORT (LER) Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or byintemet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of InformationCONTINUATION SHEET and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget,Washington, DC 20503. If a means used to impose an information collection does not display acurrently valid OMB control number, the NRC may not conduct or sponsor, and a person is notrequired to respond to, the information collection.1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGEV. C. SUMMER NUCLEAR STATION, UNIT 1 YEAR SEQUENTIAL REVNUMBER NO.05000 395 2 OF 32014 -003 -00NARRATIVE2.0 EVENT DESCRIPTIONOn April 26, 2014, during VCS Refueling Outage (RF) 21, surveillance test procedure STPI30.005L was performed to vet'if, theComponent Cooling (CC) System [CC] emergency makeup valve (XVG09627A-CC) [V] would stroke open on demand. The valvewas actuated to the open position from the Main Control Board (MCB), but the valve remained closed as documented in surveillancetest task sheet STTS 1301142-001. An immediate retest resulted in the valve opening outside of the maximum allowed stroke time often (10) seconds. The valve was declared inoperable and action taken per Technical Specifications 4.0.5, 3.7.3, and 3.7.4. In the eventthe valve did not open in an actual event, an Operator would be dispatched to manually adjust the valve off of its seat.The valve is tested on a RO1 (every refueling outage) frequency when the systems are shutdown to prevent cross-contaminating thesystems.3.0 EVENT ANALYSISIn the event of a large CC system leak or a loss of the normal makeup capability of the Demineralized Water System, each CC Systemtrain has a service water (SW) emergency makeup supply valve. Excessive CC system leakage could be detected by pressurechanges, flow rate changes, increase in the frequency and/or duration of surge tank water makeup cycles, or visual inspection of thesystem. The emergency makeup supply valves are-designed to open automatically at one foot below the low-low surge tank levelalarm setpoint to supply makeup water to the affected loop.XVG09627A-CC is a normally closed, fail open, energize to open, four inch air operated valve (AOV) located between the SW supplylines and the CC system. The valve has an air accumulator to maintain the valve closed for approximately three hours on a loss ofinstrument air. The valve fails open on loss of accumulator air, but fails closed on loss of control signal, if sufficient accumulator air isavailable. Valve XVG09627A-CC must open in 10 seconds or less to maintain required CC Pump Net Positive Suction Head (NPSH),and to provide makeup flow for a system break or through-wall crack.One side of the XVG09627A-CC valve is located in a raw water (SW) environment. The operator uses air to close which allows thegate to be firmly thrust into the seat so there is no cross contamination between the SW and CC systems. The valve is only cycledduring refueling outages to maintain the isolation of the SW system from the CC system to ensure there is no cross-contamination.In the 18 months between refueling outages, corrosion products and sediment could build-up on the seat and disc face. With this addedlayer of corrosion product and sediment, there is an increased amount of force required to remove the disc from the seat. The packingused in the valve was an older style of graphite packing that can place a higher frictional force on the stem of the valve. Greater forceis required to remove the disc from the seat due to this added frictional force.Additionally, the valve is a spring open valve. It uses four springs to remove the valve from the seat. Since the valve's safety functionis to fail open, the springs are normally in a compressed state. When springs are in a fully compressed state for long periods of timethey begin to set due to the grain structure realignment. Spring set effectively reduces the overall energy (opening force) stored in thespring.NRC FORM 366A (02-2014) 411NRC FORM 366A LICENSEE EVENT REPORT (LER) u.S. NUCLEAR REGULATORY COMMISSION(02-2014)CONTINUATION SHEET1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGEV. C. SUMMER NUCLEAR STATION, UNIT 1 YEAR SEQUENTIAL I REVNUMBER NO.05000 395 3 OF 32014 -003 -00NARRATIVE4.0 SAFETY SIGNIFICANCEWhen the plant is in Modes 1-4, the train of CC associated with XVG09627A-CC is rendered inoperable when XVG09627A-CC isinoperable. The function of XVG09627A-CC to supply makeup inventory to thle CC system is not risk significant and is notmonitored in Mitigating Systems Performance Index (MSPI) basis.During the period of unavailability of XVG09627A-CC, it was discovered that XVG09627B-CC was also inoperable(LER 2014-001-00 documents this failure). The failed stroke test of both XVG09627A-CC and XVG09627B-CC implies that bothvalves were inoperable during this period of time. A PRA risk evaluation was performed to determine the change in risk with bothvalves being out of service simultaneously. With both valves out of service simultaneously, the resulting change in risk is as follows:The delta CDF is: 3.16E-08/yrThe delta LERF is: 2.70E-10/yrThe values for increased risk are well below the thresholds for safety significance (IE-06/yr and 1E-07/yr, respectively). Therefore,the event of both valves being inoperable is of low safety significance.Reporting requirement IOCFR50.73(a)(2)(v) was made in LER 2014-001-00 for both XVG09627A-CC and XVG09627B-CC beinginoperable at the same time.5.0 PREVIOUS OCCURRENCEThere have-been no previous occurrences of XVG09627A-CC failing to stroke open in the last three years.However, XVG09627B-CC failed to stroke open when surveillance testing was performed during the fall 2012 outage (RF20) and thespring 2014 odftage (RF21). LER 2013-002-00 and LER 2014-001-00 were submitted for these events.6.0 CORRECTIVE ACTIONSThe valve was disassembled, inspected and rebuilt using new closure and trip springs. The graphite packing was replaced with Teflonpacking. The air piston actuator assembly was rebuilt. All points on the valve linkage were lubricated. The pressure regulator closingforce was also reduced.The valve was stroke tested satisfactorily after being rebuilt.NRC FORM 366A (02-2014)}}

Latest revision as of 12:10, 13 July 2018

Redirect to:

Retrieved from "https://kanterella.com/w/index.php?title=ML14177A532&oldid=883707"