Information Notice 1990-08, KR-85 Hazards From Decayed Fuel
UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555February 1. 1990NRC INFORMATION NOTICE NO. 90-08: KR-85 HAZARDS FROM DECAYED FUEL
Addressees
- All holders of operating licenses or construction permits for nuclear powerreactors and holders of licenses for permanently shutdown facilities withfuel on site.
Purpose
- This information notice alerts addressees to potential problems resulting from*the .accidental release of Kr-85 from decayed fuel. It is expected that recipients will review the Information for applicability to their facilities andconsider actions, as appropriate, to avoid similar problems. However, sugges-tions co'ntained in this information notice do not constitute NRC 'requirements;therefore, no specific action or written response is required.Desripionof Circumstances:During the licensing reviews for the Oconee independent spent fuel storageInstallation,, and in the decommissioning of the La Crosse and Dresden Unit 1power reactors, the NRC staff analyzed the radiological hazards associated.with the gases In decayed spent fuel. The age of the nuclear power industryand the lack of a permanent repository for spent fuel have resulted in theaccumulation of decayed'spent fuel.* Decayed spent fuel is manipulated afterlong shutdowns of operating reactors, during spent fuel pool re-racking, duringmo~vement to alternate reactor sites or independent spent fuel storage instal-lations, and during decommissioning. Analysis of hypothetical accidentsinvolving decayed spent fuel has focused attention on potential difficultiesthat'could be associated with the exposure of onsi1te personnel to an accidentalrelease of Kr-85. IKr-85 is a noble gas fission product that is present in thegaps between the fuel pellets and the cladding. It has a 10.76-year half-life,and, as a result of the considerably shorter half-lveso ital l tegaseous fission products (1-129 being the exception, but in low abundance),,Kr-85 becomes Increasingly the dominant nuclide in the accident source termfor gap releases as decay times increase. After 2 weeks of decay, Kr-85 isa significant nuclide in the source term, and after 190 days of decay, it isthe predominant gaseous nuclide for a gap release. The unusual decay character-istics of K~r-85 give cause for focusing attention on the onsite consequencesof a gap release from decayed fuel.,-9001260198 40--
IN 90-08February 1, 1990 Discussion:Kr-85 emits beta radiation with a maximum energy of 0.67 MeY for 99.6 percent ofthe decays and 0.51 MeV gamma radiation. for 0.4 percent of the decays. Conse-quently, direkt exposure to this gas would result in a dose to the skin approxi-mately 100 times the whole-body dose. Analysis of the relative consequences (interms of radiological doses) of a cask-drop accident as a function of decay timeof the fuel is illustrated in Figure 1. In the event of a serious accidentinvolving decayed spent fuel, protective actions would be needed for personnelon site, while offsite doses (assuming an exclusion area radius of 1 mile fromthe plant site) would be well below the Environmental Protection Agency'sProtective Action Guides. Accordingly, it is important to be able to properlysurvey and monitor for Kr-85, and to assess the skin dose to workers who couldbe exposed to Kr-85 in the event of an accident with decayed spent fuel.Licensees may wish to reevaluate whether Emergency Action Levels specified inthe emergency plan and procedures governing decayed fuel-handling, activitiesappropriately focus on concern for onsite workers and Kr-85 releases in areas'where decayed spent fuel accidents could occur, for example, the'spent fuelpool working floor. Furthermore, licensees may wish to determine if emergencyplans and corresponding implementing procedures address the means for limitingradiological exposures of onsite personnel who are in other areas of the plant.Among other things, moving onsite personnel away from the plume and shuttingoff building air intakes downwind from the source may be appropriate.This information notice requires no specific action or written response. If youhave any questions about the information in this notice, please contact one ofthe technical contacts listed below or the appropriate NRR project manager.Charles E. Ross Di ctorDivision'of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts: Charles S. Hinson, NRR(301) 492-3142Robert A. Meck, RES(301) 492-3737
Attachments:
1. Figure 1, Dose Consequences of aSpent Fuel Drop Accident2. List of Recently Issued NRC Information Notices N N..Atitchment 1IN 90-08 IFebruary 1, 1990 DOSE CONSEQUENCESOFA SPENTFUELDROPACCIDENT-103102ArMR SHUTDOWNFigure 1 Attachment 2in 90-08February 1, 1990Page I of ILIST OF RECENTLT ISSUEDNRC INFORMATION NOTICES}stanntinaV
- _Notice No.BJ-23,Supp. 2..I m ..-90-O7*90-0690-05 -90-0490-0390-0290-01_- --- 89-90 -_89-89SubjectPotential for Gas Binding.of Ngh-Prussura SsfetyInJection Pumps During aLoss-of-Coolant AccidentNew information RgardingInsulation Materal1Performance and DebrisBlockage of PWR Contain.ment SumpsPotential for Loss ofShutdown Cooling Whileat Low Reactor CoolantLevelsInter-Systes Discharge ofReactor CoolantCracking of the Upper Shell-to-TransitIon Cone 6irthWelds in Steam GeneratorsMalfunction of Borg-WarnerBolted Sonnet Check ValvesCaused by Failure of theSwing ArmPotential Degradation ofSecondary ContainsentImportance of ProperResponse to Self-IdentifledViolations by LicenseesPressurizr-Safty lLift Setpoint Shift.Eient NotificatinWorkshestsDate orIssuance1/31/901/30/90Issued toAll holders of OLsor CPs for PWRs.All holders of OLtsor CPs for nuclearpower reactors.1/29/90 All holders of OLsor CPs for nuclearpower reactors.1/29/901/26/901/23/90All holders of OLsor CPs for nuclearpower reactors.All holders'of OLsor CPs for Westinghouse-designed and CoatustionEngineering-designednuclear power reactors.All holders of OLsor CPs for nuclearpower reactors.1/22/90 All holders of OLs.or CPa for BWRs.1/12/90 All holders of NRCmaterials licenses.12t/28/81 All olbders or OLsor CPs for Prs.12/26/839 All holders of OLsor CPs for nuclearpower reactors:'OL
- Operating LicenseCP
- Construction PermitUNITED STATESNUCLEAR REGULATORY COMMISSIONWASHINGTON, D.C. 20555'!OFFICIAL BUSINESSPENALTY FOR PRIVATE USE. UOOIPOSTAGE It FEES PAIDIjusNAcj
-11 --1IN 90-08February 1, 1990 Discussion:Kr-85 emits beta radiation with a maximum energy of 0.67 MeY for 99.6 percent ofthe decays and 0.51 MeY gamma radiation for 0.4 percent of the decays. Conse-quently, direct exposure to this gas would result in a dose to the skin approxi-nately 100 times the whole-body dose. Analysis of the relative consequences (interms of radiological doses) of a cask-drop accident as a function of decay timeof the fuel is illustrated in Figure 1. In the event of a serious accidentinvolving decayed spent fuel, protective actions would be needed for personnelon site, while offsite doses (assuming an exclusion area radius of 1 mile fromthe plant site) would be well below the Environmental Protection Agency'sProtective Action Guides. Accordingly, it is important to be able to properlysurvey and monitor for Kr-85, and to assess the skin dose to workers who couldbe exposed to Kr-85 in the event of an accident with decayed spent fuel.Licensees may wish to reevaluate whether Emergency Action Levels specified inthe emergency plan and procedures governing decayed fuel-handling activitiesappropriately focus on concern for onsite workers and Kr-85 releases in areaswhere decayed spent fuel accidents could occur, for example, the spent fuelpool working floor. Furthermore, licensees may wish to determine if emergencyplans and corresponding implementing procedures address the means for limitingradiological exposures of onsite personnel who are in other areas of the plant.Among other things, moving onsite personnel away from the plume and shuttingoff building air intakes downwind from the source may be appropriate.This information notice requires no specific action or written response. If youhave any questions about the information in this notice, please contact one ofthe technical contacts listed below or the appropriate NRR project manager.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts: Charles S. Hinson, NRR(301) 492-3142Robert A. Meck, RES(301) 492-3737
Attachments:
1. Figure 1, Dose Consequences of aSpent Fuel Drop Accident2. List of Recently Issued NRC Information Notices*See Previous ConcurrenceRPB:DREP SC:RPB:DREP SC:RPB:DREP DREP D:DREP RPB:ARM C/OG :DOEA:NRCSHinson* JEWigginton* LJCunningham* LCohen* FJCongel* TechEd* CHBerlinger*01/11/90 01/11/90 01/17/90 01/17/90 01/24/90 01/25/90 01/25/90D9/DOCUMENT NAME:INFORMATION NOTICE MECK ef r, .-IIN 90-XXJanuary xx, 1990 DISTRIBUTION:FJCongel I .9LJCunningham, NRRTHEssig, NRRJEWigginton, NRRRAErickson, NRRRJBarrett, NRRRLAnderson, TTCCSHinson, NRRLKCohen, NRRCHBerlinger, NRRCERossi, NRRCentral FilesRPB R/F*See Previous ConcurrenceRPB:DREPCSHInson*01/11/90SC:RPB:DREPJEWigginton*01/11/90SC:RPB:DREPLJCunnlnghal*01/17/90DREPLCohen*01/17/90D:DREPFJCongel*01/24/90RPB:ARMTechEd*01/25/90C/d@CB:DOEA:NRRCHBerlingerO1/jVi90D/DOEA:NRRCERossi01/ /90DOCUMENT NAME:INFORMATION NOTICE MECK
- *}. 'IN 90-XXJanuary xx, 1990 No specific action or written response is required by this information notice.If you have any questions about this matter, please contact one of the technicalcontacts listed below or the Regional Administrator of the appropriate regionaloffice.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts:Charles S. Hinson, NRR(301) 492-3142Robert A. Heck, RES(301) 492-3737
Attachments:
1.2.Figure 1List of Recently Issued NRC Information NoticesRPB:DREP SC lPJgBREPCSHinsoIMJ pginton01/ll /so ° /90D/DOEA:NRRCERossi01/ /904 Cu Ingham LCohen01/7/90 1/%A 190D:DRE 2 PB:MfFJConge Tol1zq/90 01&5/90onrC/OGCB:DOEA:NRRCHBerlinger01/ /90