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{{Adams
#REDIRECT [[IR 05000277/2010010]]
| number = ML111890441
| issue date = 07/08/2011
| title = IR 05000277-10-010 on 11/01/2010 - 05/27/2011, Peach Bottom, ISFSI Inspection
| author name = Joustra J A
| author affiliation = NRC/RGN-I/DNMS/DB
| addressee name = Pacilio M J
| addressee affiliation = Exelon Nuclear, Exelon Generation Co, LLC
| docket = 05000277
| license number = DPR-044
| contact person =
| document report number = IR-10-010
| document type = Inspection Report, Letter
| page count = 12
}}
See also: [[followed by::IR 05000277/2010010]]
 
=Text=
{{#Wiki_filter:UNITED STATESNUCLEAR REGULATORY COM MISSIONREGION I475 ALLENDALE ROADKING OF PRUSSIA, PENNSYLVANIA 19406-1415July 8,2011Docket No. 05000277 License No. DPR-44MichaelJ. PacilioSenior Vice President, Exelon Generation Company, LLCPresident and Chief Nuclear Officer, Exelon Nuclear4300 Winfield RoadWarrenville. lL 60555SUBJECT:PEACH BOTTOM ATOMIC POWER STATION - NRC ISFSI INSPECTIONREPORT 05000277 1201 00 1 0Dear Mr. Pacilio:On November 1 , 2010 through May 27 ,2011 , Mark Roberts, John Nicholson, and StephenHammann of this office conducted a safety inspection at the Peach Bottom Atomic PowerStation of activities authorized by the above listed NRC license. The inspection was limited to areview of routine and non-routine (helium leak of cask #1) activities associated with dry fuelstorage at the Peach Bottom Atomic Power Station and its Independent Spent Fuel StorageInstallation (lSFSI). The findings of the inspection were discussed with Garey Strathes, andother members of your staff of your organization, at the conclusion of the inspection. Theenclosed report presents the results of this inspection.The inspection examined activities conducted under your license as they relate to compliancewith the Commission's rules and regulations and with the conditions of your license. Theinspectors reviewed selected procedures and records, observed activities, and interviewedpersonnel.Based on the results of thisno findings of significance were identified.In accordance with 10 CFR Part 2.390 of the NRC's "Rules of Practice," a copy of this letter, itsenclosure, and your response (if any) will be available electronically for public inspection in theNRC Public Document Room or from the Publicly Available Records component of the NRC'sdocument system (ADAMS). ADAMS is accessible from the NRC Web Site athttp ://vr,rww. nrc. qov/readi no-rm/adams. html (the Pu blic Electric Reading Room).
M. PacilloThank you for your cooperation during this inspection.Enclosure:lnspection Report No. 05000277 l2O1OO1Occ: dencl: Distribution via List ServDecommissioning BranchDivision of Nuclear Materials Safety
M. PacilloThank you for your cooperation during this inspection.Enclosure:f nspection Report No. 05000277 12010010cc: Mencl: Distribution via List ServDistribution w/encl: (via E-mail)W. Dean, RA (RIORAMAIL Resource)D. Lew, DRA (RIORAMAlL Resource)D. Roberts, DRP (RIDRPMAlL Resource)J. Clifford, DRP (RIDRPMAlL Resource)C. Miller, DRS (RlDRSMailResource)P. Wilson, DRS (RlDRSMail Resource)P. Krohn, DRPA. Rosebrook, DRPE. Torres, DRPE. Benner, NMSSJ. Joustra, DNMSR. Lorson, DNMSD. Collins, DNMSM. Roberts, DNMSS. Hammann, DNMSJ. Nicholson, DNMSD. Screnci, PAON. Sheehan. PAOSincerely,/RA/ Kathy Modes for:Judith A. Joustra, ChiefDecommissioning BranchDivision of Nuclear Materials SafetyS. lbarrola. DRPF. Bower, DRP, SRIA. Ziedonis, DRP, RlS. Schmitt, DRP, OAS. Bush-Goddard, Rl OEDORidsNrrPMPeachBottom ResourceRidsNrDorlLpl 1 -2 ResourceROPreoorts ResourceDOCUMENT NAME: G :\WordDocs\Current\lnsp Letter\LDPR-44.201 00 1 0'docSUNSI Review Complete: MRoberts ML111890441After declaring this document 'An Official Agency Record' it will be released to the Public.acoDvofthisdocument,indicateinthebox:'C'=CopyWoattach/encl "E"=copywanacn/encl "N"=OFFICEDNMS/RI I NDNMS/RIDNMS/RIDNMS/RINAMEMRoberts/mcrJNicholsonimcr for:SHammann/sthJJoustra/kdm forDATE071081201107t08t201107t08t20110710812011OFFICIAL RECORD COPY
lnspection No.Docket No.License No.Licensee:Location:Inspection Dates:lnspectors:Approved By:U.S. NUCLEAR REGULATORY COMMISSIONREGION IINSPECTION REPORT45400277t201001005000277DPR-44Exelon NuclearPeach Bottom Atomic Power Station1848 Lay RoadDelta, PA.17314November 1,2010 - May 27,2011Mark Roberts, Senior Health PhysicistDecommissioning BranchDivision of Nuclear Materials SafetyStephen Hammann, Senior Health PhysicistDecommissioning BranchDivision of Nuclear Materials SafetyJohn Nicholson, Health PhysicistDecommissioning BranchDivision of Nuclear Materials SafetyFred Bower, Peach Bottom Senior Resident InspectorBranch 4Division of Reactor ProjectsAdam Ziedonis, Peach Bottom Resident lnspectorBranch 4Division of Reactor ProjectsJudith A. Joustra, ChiefDecommissioning BranchDivision of Nuclear Materials SafetyDocument Name: G:\WordDocs\Current\lnsp Report\RDPR-44.201 001 0.doc
EXECUTIVE SUMMARYExelon NuclearPeach Bottom Atomic Power StationNRC lnspection Report No. 0500027712010010The inspection was a review of spent fuel storage activities at the Peach Bottom Atomic PowerStation and the Independent Spent Fuel Storage lnstallation (lSFSl) at the site. The inspectionincluded a review of activities during a routine spent fuel storage campaign and thetroubleshooting, unloading, root cause evaluation, and corrective action development of aloaded spent fuel storage cask that had developed a helium leak in the main lid seal. The reportcovers announced safety inspection visits conducted by three regional inspectors with supportfrom two NRC resident inspectors. The inspection included an evaluation of the licensee'sprograms for radiation protection, maintenance, and operations as they related to routinepreparation, loading, and transport of a spent fuel cask and the non-routine activities associatedwith troubleshooting the helium leak, opening and unloading a loaded cask, conducting a causalanalysis for the leaking cask, and developing and implementing corrective actions.The licensee safely implemented its maintenance, radiation protection, and operations programsto support routine and non-routine activities associated with dry fuel storage.Based on the results of this inspection, no findings were identified.lnspection Report No. 05000277 12010010G:\WordDocs\Current\lnsp Report\RDPR-44.201 001 0.doc
1.0a.b.REPORT DETAILSHelium Leak ldentification on ISFSI Gask #1lnspection ScopeThe inspectors reviewed the activities related to the response to a low pressure alarmcondition on spent fuel storage cask TN-68-01. The inspectors interviewed personneland reviewed the licensee's relevant documents.Observations and FindinqsExelon Nuclear utilizes the Transnuclear, Inc. (Transnuclear) TN-68 cask storage systemat the Peach Bottom site for storage of spent fuel assemblies at its lSFSl. TheTN-68casks are vertical stainless steel casks with bolted lids. A metal (aluminum-clad) O-ringseal with an inner and an outer sealing surface is fitted into a groove in the bottom of thecask lid. After loading a cask in the fuel pool with spent fuel assemblies, the cask lid isbolted on and residual moisture is removed from the cask. When the lid bolts aretorqued into the lid, the two sealing surfaces of the metal O-ring are compressed againstthe top of the cask to form two seals. Access to the cask once the lid is in place isthrough a pair of vent and drain ports. The cask is back-filled with helium and the drainand vent ports are bolted on. The vent and drain port covers also have metal O-ringseals with inner and outer sealing surfaces. The helium backfill provides an inert storageenvironment. A helium overpressure tank, positioned on a small port on the cask lid,supplies helium overpressure to the space between the cask seals. The combinedhelium leak rate for all closure seals and the overpressure system is continuouslymonitored for indications of helium leakage and compliance with the Certificate ofCompliance (COC) technical specifications. A bolted on carbon steel protective cover,with an elastomer O-ring seal, provides environmental protection for the cask lid andhelium pressurization system. Currently approximately 50 casks are stored at the PeachBottom lSFSl.On October 11,2010, a cask seal overpressure monitoring system low pressure alarmwas received for Cask TN-68-01. This cask was initially loaded with spent fuelassemblies on June 12,2000, and was in storage at the lSFSl. Preliminary helium leak-testing was conducted at the lSFSl. In order to perform further troubleshooting of the lowpressure alarm, the overpressure monitoring system was re-pressurized and the caskwas moved to the Unit 2 Containment Building. Testing conducted on October 27,2010,identified that a helium leak existed in the cask main lid sealing area at a leak rategreater than allowed by the ISFSI cask COC technical specifications.No findings of significance were identified.ConclusionsThe licensee identified and responded to a cask seal overpressure monitoring systemlow pressure alarm for Cask TN-68-01. The cask was safely moved to the Unit 2Containment Building where testing confirmed a helium leak in the cask main lid sealingarea at a leak rate greater than allowed by the ISFSI cask COC technical specifications.1 Inspection Report No. 0500027712010010G:\WordDocs\Current\l nsp Report\RDPR-44.20 1 00 1 0.docc.
2.0Helium Leak Troubleshooting on ISFSI Gask #1Inspection ScopeThe inspectors reviewed the activities related to troubleshooting the low pressure alarmcondition on cask TN-68-01. The inspectors observed troubleshooting activitiesperformed on the cask, interviewed personnel, and reviewed the licensee's relevantdocuments.Observations and FindinqsThe licensee, in consultation with Transnuclear, re-torqued each of the 48 cask lid boltsprogressively to a level of 900 foot-pounds. The bolt torque sequence was provided byTransnuclear. Torquing was repeated until there was no visual movement of any bolthead. The licensee then performed a sequence of helium leak tests and identified thatthe outer sealing surface of the main cask lid seal was leaking. The cask inner seal andthe seals on the vent and drain ports were confirmed to be functional. Although thelicensee was able to reduce the helium leak-rate to levels below the requirements of theCOC technical specifications, they decided that they did not want to return the cask tolong-term storage at the lSFSl. Plans were then developed to breach the cask andunload the spent fuel assemblies back into the spent fuel pool in order to performadditional inspections on the cask lid and seals.No findings of significance were identified.ConclusionsThe licensee conducted helium leak test troubleshooting of a loaded spent fuel storagecask and confirmed that the outer sealing surface of the main cask lid seal was leaking.Plans were developed to breach the cask and unload the spent fuel assemblies back intothe spent fuel pool in order to perform additional inspections on the cask seals.Spent Fuel Unloading Activities for ISFSI Cask #1lnspection ScopeThe inspectors reviewed the licensee's activities associated with opening the cask,returning the cask to the spent fuel pool, and unloading the spent fuel back into the spentfuel poolfuel storage racks. The inspectors interviewed licensee personnel, reviewedplanning documents, and directly observed activities associated with opening, moving,and unloading the spent fuel cask.Observations and FindinosThe licensee had confirmed through testing that each of the fuel assemblies that wereloaded into the cask were not leaking, when the cask was initially loaded. However,because the condition of the fuel assemblies in the cask were unknown after ten years ofstorage, licensee staff took conservative measures in coordinating maintenance andradiation protection activities to safely breach the cask. In addition to their own practical2 Inspection Report No. 0500027712010010G:\WordDocs\Cunent\l nsp Report\RDPR-4 4.201 001 O.doca.b.3.0a.c.b.
c.experience gained from loading spent fuel casks, the licensee used operating experiencegained from another operating nuclear power plant licensee that breached loaded fuelcasks with a similar helium leak problem. Major concerns that were considered if the fuelintegrity had not been maintained were the potential for elevated radiation levels at thedrain and vent port covers, high activity discrete radioactive particles, and release offission product gasses. Pre-job briefings by maintenance and radiation protectionpersonnelwere thorough and appropriately emphasized the areas of major concern.Radiation protection surveys did not identify significantly elevated radiation levels ordiscrete radioactive particles. Radiological surveys and sampling and analysis of theatmosphere in the cask did not identify any release of fission product gasses once thecask was breached. The cask was then placed in the Unit 2 fuel pool for removal of thelid and unloading the fuel assemblies. The cask lid and cask were returned to Unit 2 fuelfloor for inspection and evaluation.No findings of significance were identified.ConclusionsThe licensee safely implemented its plan for breaching the spent fuel cask, placing thecask in the spent fuel pool, removing the cask lid, unloading spent fuel from the cask,and returning the cask lid and cask to the fuel floor for inspection. No unusual orunexpected conditions were identified.Evaluation and Gorrective Action Activitieslnspection ScopeThe inspectors reviewed the licensee's activities associated with the cask sealevaluation, extent of condition implications, and corrective actions that had beenimplemented and proposed. The inspection consisted of field observations, review oflicensee documentation, and interviews with responsible personnel.Observations and FindinqsLicensee and cask vendor personnel inspected the cask, cask lid, cask lid seals, ventand drain cover seals, protective cover, and the sealing surfaces on the protective cover.The inspections of the protective cover were performed during the initial caskdisassembly on the fuel floor. The inspections of the cask, lid, and seals were conductedafter the unloaded cask was returned to the fuel floor. The initial evaluation revealedcorrosion of the main lid outer seal, lower-than-expected torque on some of the main lidbolts, and corrosion on the threads of the lid bolts. The inner seal remained intact, andtherefore the cask's primary containment was not compromised. Observations when theprotective cover was removed found streaks of rust on the underside of the cover, apronounced pattern of rust directly under the access plate, and water or signs of moisturearound most of the bolt lid holes and bolts. The elastomer O-ring seal on the bottom ofthe protective cover was found to be completely intact and sealed against the top of thecask lid.lnspection Report No. 05000277 12010010G :\WordDocs\Current\l nsp Report\RDPR-44.201 001 0.doc4.0a.b.
c.In order to determine the root cause of the event, the licensee initiated a root causeevaluation that included licensee and vendor personnel. The evaluation team concludedthat the mechanical cause of the helium leak was determined to be galvanic corrosion ofthe main lid's outer seal due to the presence of moisture at the interface of thealuminum-clad seal and the stainless steel cask body. The presence of the moisture atthe interface of the two dissimilar metals set up a galvanic cell that caused the aluminumto corrode and allow helium to leak through the outer seal of the metal O-ring. Thehelium leak test detection system performed its intended function.The evaluation team identified two root causes for the event; both associated with theperformance of the protective cover that was intended to prevent water infiltration. Thefirst root cause was determined to be an inadequate design for sealing the access platein the protective cover. The second root cause was the lack of any verification of theintegrity of the water-tight cover. Based on the identified root causes, the licenseedeveloped two primary corrective actions and additional corrective actions to preventrecurrence of the event. The two primary corrective actions, both intended to maintainthe integrity of the protective cover, include improving the design of the access plate anddeveloping a verification method for the integrity of the protective cover seals. Thelicensee and cask vendor are currently working on a redesign of the protective cover anddeveloping a method for testing the integrity of the cover. Installation and testing forCask #1 is planned for mid-2012. Additional corrective actions include a change to thetorquing process for the lid bolts and ensuring that the access plate gasket andprotective cover O-ring are inspected at installation. These changes are incorporated inthe current procedure revision.As part of the extent-of-condition review, the licensee has planned inspections for waterinfiltration under the protective cover for the remaining casks that have been previouslyloaded. Casks with a similar protective cover design (casks #2 - #9) are scheduled fortesting in August 201 1 followed by testing of the remaining casks (#10 - #52) that hadprevious design changes of the protective covers. Replacement of covers is expected tobe based on the test results.No findings of significance were identified.ConclusionsThe licensee conducted evaluations to determine the root cause of the helium-leak eventand concluded that the mechanical cause of the event was corrosion of the lid seal fromwater infiltration through the protective cover. The licensee identified two root causes ofthe event, both related to performance of the protective cover. Long-term correctiveactions to redesign the access plate to the protective cover and develop an enhancedcask monitoring method are in the design stages by the licensee and cask vendor andare expected to be completed and implemented in mid-2012. Short{erm correctiveactions including procedure changes for bolt torquing and verification steps forconfirming the integrity of the elastomer seals on the protective cover and protectivecover access plate have been implemented. As part of its extent of condition review, thelicensee has planned testing of the protective covers of the remaining loaded casks.lnspection Report No. 05000277 12010010G :\WordDocs\Current\lnsp Report\RDPR-44.20 1 001 0.doc
5.0a.b.ISFSI Routine Loading CampaignInspection ScopeThe inspectors observed a routine ISFSI loading campaign from May 23,2011 to May27,2011. The inspection consisted of field observations, review of licensedocumentation, and interviews with responsible personnel.Observations and FindinosThe inspectors observed a portion of the cask preparation activities and movement of thecask from the preparation area into the spent fuel pool. The inspectors then observedthe loading of spent fuel into the cask by the licensee's fuel handlers. The fuelassemblies were properly identified and verified before being moved into the cask. Thelicensee's reactor engineers did a further verification that the correct fuel assemblies hadbeen loaded by making a video recording of the fully-loaded cask and viewing therecording for the identification numbers of the fuel assemblies. The inspectors alsoviewed portions of the video recording to spot check that the correct spent fuelassemblies were in the correct locations. The inspectors observed the placement of thelid on the cask, the removal of the cask from the spent fuel pool and subsequent drainingof the cask and decontamination of the cask. Inspectors also observed placement of theneutron shield, gamma shield and protective cover on the cask as well as part of theoverpressure system installation. Inspectors toured the ISFSI pad and the GentralAlarmStation and viewed the alarm system for the cask overpressure system. All ISFSIprocedures and procedures for ISFSl-related activities were examined. The personnelinvolved in the various ISFSI activities were interviewed and found to be knowledgeableand experienced. The pre-job briefings were thorough and covered all aspects of theactivity to be performed.No findings of significance were identified.ConclusionsThe licensee successfully performed the cask loading and storage on the ISFSI pad.The licensee has a documented ISFSI program and trained personnel needed to meetthe criteria set forth in the Certificate of Compliance (CoC), Final Safety Analysis Report(FSAR), and NRC regulations for an lSFSl.Exit Meetinq SummarvThe inspection results were discussed with Garey Stathes, Site Manager and members of hisstaff on May 27,2011, at the conclusion of on-site inspection activities.ATTACHMENT: SUPPLEMENTAL INFORMATIONlnspection Report No. 05000277 12010010G:\WordDocs\Current\lnsp Report\RDPR-44.201 00 1 0.docc.5
SUPPLEMENTAL INFORMATIONPARTIAL LIST OF PERSONS CONTACTEDLicenseeJim Armstrong, Regulatory Assurance ManagerJimmy Carter, Reactor Services Manager - Oyster CreekBrian Cummings, Site Reactor Services ManagerMark Dedrich, ISFSI Project ManagerNick Dube, Reactor Services SupervisorDave Foss, Regulatory AssuranceStuart Gray, Fuel Handling DirectorSteve Hess, NOS ManagerCarl Kelly, Reactor Services SupervisorDan Kern, Lead Radiation Protection TechnicianBrian Kozemchak, Work Group SupervisorPat Navin, Operations DirectorSarah Shewmaker, Reactor EngineerRon Smith, Regulatory AssuranceGarey Stathes, Plant ManagerMike Summers, Reactor Services SupervisorINSPECTION PROCEDURES USED60855 Operation of an Independent Spent Fuel Storage Installation60855.1 Operation of an Independent Spent Fuel Storage Installation at Operating PlantsITEMS OPEN. CLOSED. AND DISCUSSEDNoneLIST OF DOCUMENTS REVIEWED50.59 Evaluation No. PB-2010-02-E50.59 Screening No. PB-2010-019-57 2.48 Screening PB-201 1 -40-S72.75 (g) Cask Event Report, December 1,2010AR 01 131123 Report, ISFSI Cask #1 - Potential Helium LeakAR 01201309 Report, ISFSI Cask #1 - Prepare for StorageAR 01202466 Report, Site Align With ISFSI CoC and FSAR ReviewAR 01207763 Report, lnspect ISFSI Casks 2-9 for Water IntrusionAR01207767 Report, Inspect ISFSI Casks 10-20 forWater IntrusionAR01207768 Report, lnspect ISFSI Casks 21-52 for Water IntrusionAR01214782 Report, ISFSI Cask 45 Main Lid Binding On Guide PinsAR 01219452 Report, ISFSI Cask TN-68-47 0 Degree Upper Trunnion GaugeECR PB 10-00061 000, Incorporate TN-68 Amendment 1ECR PB 11-00099 000, Process Rev. 5 of TN-68 Dry Storage Cask FSAR6 lnspection Report No. 0500027712010010G:\WordDocs\Current\lnsp Report\RDPR-44.201 00'l 0.doc
ECR PB 11-00250 000, Removal of ISFSI Cask Alignment Pin for Lid InstallationFH-35, Control of Material Movement in the Fuel PoollR 1131123 ISFSI Cask #1 Helium Leakage - Root CauseLetter TN to PB, Subject: Guidance for Rework of Damaged TN-68-47-0 Upper TrunnionLS-AA-104-1001, 50.59 Review Coversheet FormLS-AA-1 04-1 002, 50.59 Applicability Review FormLS-AA-1 04-1004, 50.59 Evaluation Form PB-201 0-02-EMA-AA-71 6-008, Foreign Material Exclusion RequirementsMicro ALARA Ptan 10-085, ISFSI Cask 1 (TN-68-1), Transport to/from pad, Troubleshoot,Repair & Associated SupportMicro ALARA Plan 10-086, ISFSI Cask 1 (TN-68-1), Insert into SFP, Unload and/or repair mainlid sealRT-W-071-901-2,ISFSI Cask and Storage Area InspectionSF-150, Control of Cask Placement and Location on ISFSI PadSF-210, Preparation For An lndependent Spent Fuel Storage lnstallation CampaignSF-220, Spent Fuel Casks TN-68-01 through TN-68-47 Loading and Transport OperationsSF-250, Varian 979-70 Helium Leak Detector Operations and CalibrationSF-290, Spent Fuel Cask Transport and Unloading OperationsSF-300, TN-68 Cask Spent FuelAssemblies Storage Selection and Document RequirementsSF-420, Radiation Protection Requirements During Spent Fuel Cask Loading and TransportOperationsSF-490, Radiation Protection Requirements During Spent Fuel Cask Unloading and TransportOperationsST-H-071-804-2, ISFSI Casks TN-68-48 through TN-68-52 Surface Dose Rate andContaminationTN-68 Generic Technical SpecificationsTN Drawing9T2-30-1TN Drawing 972-70-2LIST OF ACRONYMS USEDADAMS Agency Wide Document Access and Management SystemCFR Code of Federa.l RegulationsCOC Certificate of ComplianceFSAR Final Safety Analysis ReportISFSI Independent Spent Fuel Storage InstallationNRC Nuclear Regulatory Commissionlnspection Report No. 05000277 12010010G :\Word Docs\Current\l nsp Report\RDPR-44.20 1 00 1 0.doc
 
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