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{{Adams
#REDIRECT [[05000237/LER-2015-001]]
| number = ML15125A018
| issue date = 04/30/2015
| title = LER 15-001-01 for Dresden, Unit 2, Regarding Scram Due to Feedwater Level Control Issues
| author name = Marik S M
| author affiliation = Exelon Generation Co, LLC
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000237
| license number = DPR-019
| contact person =
| case reference number = 15-0033
| document report number = LER 15-001-01
| document type = Letter, Licensee Event Report (LER)
| page count = 4
}}
 
=Text=
{{#Wiki_filter:Ad N Dresden Nuclear Power Station6500 North Dresden RoadAmw Exeton Generation Morris, ,L 60450 815 942 2920 Telephonewww.exeloncorp.com10 CFR 50.73SVPLTR # 15-0033April 30, 2015U. S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555-0001Dresden Nuclear Power Station, Unit 2Renewed Facility Operating License No. DPR-1 9NRC Docket No. 50-237
 
==Subject:==
Licensee Event Report 237/2015-001-01, Unit 2 Scram due to Feedwater LevelControl IssuesEnclosed is Licensee Event Report 237/2015-001-01, "Unit 2 Scram due to Feedwater LevelControl Issues." This is an interim report which describes events which are being reported inaccordance with 10 CFR 50.73(a)(2)(iv)(A), any event or condition that resulted in manual orautomatic actuation of any of the systems listed in paragraph (a)(2)(iv)(B).There are no regulatory commitments contained in this submittal.Should you have any questions concerning this letter, please contact Mr. Bruce Franzenat (815) 416-2800.Respectfully,Shane M. MarikSite Vice PresidentDresden Nuclear Power StationEnclosure Licensee Event Report 237/2015-001-01cc: Regional Administrator -NRC Region IIINRC Senior Resident Inspector -Dresden Nuclear Power Station NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2011',02-2014)ý.,,,014) Estimated burden per response to comply with this mandatory collection request: 80 hours.Reported lessons learned are incorporated into the licensing process and ted back to industry.Send comments regarding burden estimate to the FOIA, Privacy and Information Collections( RBranch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or byLICENSEE EVENT REPORT (LER) interet e-mail to lntocollects.Resource@nrc.gov, and to the Desk Officer, Office ot Intormaton(See Page 2 for required number of and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget,digits/characters for each block) 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 NUMBER 3. PAGEDresden Nuclear Power Station, Unit 2 05000237 1 OF 34. TITLEUnit 2 Scram due to Feedwater Level Control Issues5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVEDMONT A YEAR YEAR SEQUENTIAL REV MOT A ER FACILITY NAME DOCKET NUMBERNUMBER NO. MONTH DAY YEAZFACILITY NAME DOCKET NUMBER01 1 05 2015- 001 -01 04 30 15I9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)[1 20.2201(b) [] 20.2203(a)(3)(i) E] 50.73(a)(2)(i)(C) E] 50.73(a)(2)(vii)El 20.2201(d) El 20.2203(a)(3)(ii) El 50.73(a)(2)(ii)(A) El 50.73(a)(2)(viii)(A)El 20.2203(a)(1) El 20.2203(a)(4) El 50.73(a)(2)(ii)(B) E] 50.73(a)(2)(viii)(B)__ 20.2203(a)(2)(i) E] 50.36(c)(1)(i)(A) El 50.73(a)(2)(iii) E] 50.73(a)(2)(ix)(A)10. POWER LEVEL El 20.2203(a)(2)(ii) El 50.36(c)(1)(ii)(A) Z 50.73(a)(2)(iv)(A) [E 50.73(a)(2)(x)El 20.2203(a)(2)(iii) El 50.36(c)(2) [] 50.73(a)(2)(v)(A) El 73.71 (a)(4)100 20.2203(a)(2)(iv) El 50.46(a)(3)(ii) El 50.73(a)(2)(v)(B) El 73.71 (a)(5)El 20.2203(a)(2)(v) El 50.73(a)(2)(i)(A) El 50.73(a)(2)(v)(C) El OTHEREl 20.2203(a)(2)(vi) E 50.73(a)(2)(i)(B) El 50.73(a)(2)(v)(D) Specityin Abstract belowor in__________________ ___________________ ____________________ ______________N____FoNRCForm66A12. LICENSEE CONTACT FOR THIS LERLICENSEE CONTACT TELEPHONE NUMBER (Include Area Code)Bruce Franzen -Regulatory Assurance Manager 1 815-416-280013. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORTCAUSE SYSTEM COMPONENT MANU. REPORTABLE CAU SE SYSTE OPNN MANU- REPORTABLEFACTURER TO EPIX FACTURER TO EPIXX JB CPU B045 Y14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED MONTH DAY YEARSUBMISSION[E YES (If yes, complete 15. EXPECTED SUBMISSION DATE) E NO DATEABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)On January 13, 2015, operators inserted a manual scram on Unit 2 due to increasing reactor water level. It was determined that theFeedwater Level Control (FLWC) system had failed. All control rods inserted, all systems responded as expected. The FWLCsystem was repaired and the unit was returned to operation on January 16, 2015On February 6, 2015, during maintenance activities to continue troubleshooting FWLC alarms, a reactor water level transient wasinduced. An automatic scram occurred due to low reactor vessel water level. During the transient, High Pressure Coolant Injection(HPCI) was initiated, but proceduralized operator response actions prevented injection. The Unit 2 and 2/3 Emergency Dieselgenerators started but did not load on to their respective busses as offsite power was not lost.During both events, main feedwater was maintained in accordance with station operating procedures.These events are being reported under 10 CFR 50.73(a)(2)(iv)(A) "Any event or condition that resulted in manual or automaticactuation of any of the systems listed in paragraph (a)(2)(iv)(B)... "The cause of these events has been determined to be spurious power interruption on a historically improperly landed power supplyribbon cable connection for the digital FWLC system. These events are considered of very low safety significance. Correctiveactions include repairs to the ribbon cable connection and improvements to the troubleshooting process implementation.NRC FORM 366 (02-2014)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017:02-2014)Estimated burden per response to comply wth 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 by-.... LICENSEE EVENT REPORT (LER) intemet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Informationand Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget,CONTINUATION SHEET Washington, DC 20503. If a means used to impose an intormation 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. PAGEYEAR SEQUENTIAL REVYEAR I N UMBER NO.Dresden Nuclear Power Station, Unit 2 05000237 2 OF 32015 001 -01NARRATIVEPLANT AND SYSTEM IDENTIFICATIONDresden Nuclear Power Station (DNPS), Unit 2, is a General Electric Company Boiling Water Reactor with alicensed maximum power level of 2957 megawatts thermal. The Energy Industry Identification System codesused in the text are identified as [XX].A. Plant Conditions Prior to Event:Unit: 02 Event Date: 01/13/15 and 02/16/15 Event Time: 1903 and 1227 CSTReactor Mode: 1 Mode Name: Power Operation Power Level: 100 percentB. Description of Event:On January 13, 2015, operators inserted a manual scram on Unit 2 due to increasing reactor waterlevel. It was determined that the Feed Water Level Control [JB] (FWLC) system had failed. All controlrods inserted, all system responded as expected. The FWLC system processor cards were replaceand the unit was returned to operation on January 16, 2015On February 6, 2015, during maintenance activities to continue troubleshooting additional FWLCalarms, the reactor water level increased as a result of a momentary interruption in the FWLC powersupply. Feedwater regulating valves were manually operated to control reactor water level, howeverthe transient resulted in an automatic scram due to low reactor vessel water level. During the transient,High Pressure Coolant Injection [BJ] (HPCI) was initiated, but proceduralized operator response actionsprevented injection. The Unit 2 and 2/3 Emergency Diesel generators [EK] started but did not load onto their respective busses as offsite power was not lost.During both events, main feed water [SJ] flow was maintained in accordance with station operatingprocedures.These events are being reported under 10 CFR 50.73(a)(2)(iv)(A) "Any event or condition that resultedin manual or automatic actuation of any of the systems listed in paragraph (a)(2)(iv)(B)...C. Cause of Event:The cause of these events was a spurious power interruption on a historically improperly landed powersupply ribbon cable connection for the digital FWLC system, which caused a momentary 5Vdc powersupply loss to the FWLC Multi-Function Processors (MFP). The loss of power resulted in a runback ofthe 2A Reactor Recirculation [AD] pump and a reactor level transient. The runback signal from FWLCwas caused by mis-positioned DIP switches on another FWLC digital circuit board.A second root cause for the scram on 02/06/15 was less than rigorous organizational challenge oftroubleshooting activities, and less than rigorous troubleshooting that allowed the conditions to remainundetected following the scram on 01/13/15. The troubleshooting was focused upon a pre-conceivedassumption of the issue and did not fully validate all potential causes nor challenge their disposition.NRC FORM 366A (02-2014)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION(02-2014) LICENSEE EVENT REPORT (LER)CONTINUATION SHEET1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGESEQUENTIAL I REVYEA NUMBER I NO.Dresden Nuclear Power Station, Unit 2 05000237 YEAR_ NUMBERNO.I3 OF 32015 001 01NARRATIVED. Safety Analysis:Following the actuations, all other systems responded as expected, therefore, this event isof low safety significance.E. Corrective Actions:1. The degraded five-ribbon cable was replaced per WO 01805706-03, with five single-ribbon cablesper the vendor's recommendations.2. Develop and present a Case Study from this RCR that specifically highlights the level of challengeneeded to ensure that a troubleshooting problem is thoroughly understood to the SeniorManagement Team, Engineering, and Maintenance.3. Improve the formality and rigorous use of the troubleshooting process by performing the following:* Brief lessons learned from RCR 2437067-02 at an Engineering All-Hands Meeting.* Brief the troubleshooting process with the Engineering management team.* Perform training on the Troubleshooting process emphasizing the correct mindset, beingopen-minded about other potential causes, and comprehensive. Train the engineeringpopulation on the troubleshooting issues associated with this root cause.* Increase oversight of the troubleshooting teams for the next six months with senior managerobservations of troubleshooting activities and troubleshooting briefs.4. Revise Unit 2 and Unit 3 Preventive maintenance Model WOs to document as-found/as-leftpositions of DIP switches and other positionable components if circuit cards are removed.5. Correct Unit 2 DIP Switch Positions.6. Perform a review of 100% of open Complex Troubleshooting Support/Refute Matrices and review100% of the matrices closed within last year.7. Station Manager/Site VP to review root cause with site senior management and emphasize thechallenges missed.8. Review existing event response procedures checklist for team initiation and review of roles andresponsibilities.F. Previous Occurrences:No previous occurrences of this event were determined through the investigation.G. Component Failure Data:Manufacturer Model S/N TypePTJED11391 ModuleBailey YIMMFP12 andPTJED1 1487 AssemblyNRC FORM 366A (02-2014)}}

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