Regulatory Guide 1.13

Spent Fuel Storage Facility Design Basis

ML13350A371
Person / Time
Issue date:	12/31/1975
From:	NRC/OSD
To:
References
RG-1.013, Rev. 1
Download: ML13350A371 (3)

U.S. NUCLEAR REGULATORY COMMISSIONREGULATORY GUIDEOFFICE OF STANDARDS DEVELOPMENTRevision 1December 1975REGULATORY GUIDE 1.13SPENT FUEL STORAGE FACILITY DESIGN BASIS

A. INTRODUCTION

1. Loss of Water from Storage Pool*1.General Design LrtIerilon oi, rue, atoragt andi Unless protective measures are taken, loss of waterHandling Criteria for Nuclear Power Plants," of Appen- from a fuel storage pool could cause ove~htating of thedix A, "General Dsign Critria for Nuclear Power spent luel and resultant damage to ftef-cladding integ-Plants," to 10 CFR Part 50, "Licensing of Production i l l ee .,*'c to..... ..... ." .. .... rity and could result in release of rapoactiv.piaterials toand Utilzation Facilities," requires that fuel storage and the environment, Natural events as .a q orhandling systemls be designed to assure adequate safety s..... coue aamage "uia ue or.... ... .. m~~hgh winds, coul damamge arcyounder norm al and postulated accident conditions. It also bytthe g nera ion. o .._c-r directly or....... ... .. by the generation of t&igihnilS or highl windsrequires that these systems be designed with appropriate hiuld winso cause ,,,d,-,,, ,,, to fasn th,containment, confinement, and filtering systems and be could also c.un s he fa` ,eto. withsta..n to fall noctdesigned to prevent significant recduction in the L.oolant polcesiwith c f-caloJfwithsta t occur-inventory of the storage facility under accident condi- wen w......ithu. of.w.tertig tgrty..... , .ulo u~cwz¢ tC9 Oceras.tions. This guide describes a method acceptable to the wud "he.. c cn.NRC staff for implementing this criterion.Drftiling olheavy loads, such as a 100-ton fuel cask,DISCUSSIONW " w ro y

B. DISCUSSION

w o probability, cannot be ruled out in plant." t ents where such loads are positioned or movedIt is important that futel handling and storage iIt di to: lin-r over the fuel pool. Possible solutions to thisbe designed to"potential problem include (1) preventing, preferably bya. Prevent lotdesign rather than interlocks, heavy loads from beinga. P t lo lifted over the pool; (2) using a highly reliable handlingwould uncover fuel. sys:em designed to prevent dropping of heavy loads as aresult of any single failure; or (3) designing the pool tob. Protect the fuel from mechanical damage. withstand dropping of the load without significantS. .... leakage from the pool area in which fuel is stored.Ic. Provide the capa y .limiting the potentialoffsite exposures in the ificant release ofradioactivity fro .If spe el rage cilities are not located withinthe priý a , ontainment or provided withadequate ective features, radioactive materials couldbe released the environs as a result of either loss ofwater from the storage pool or mechanical damage tofuel within the pool.'*Lines indicate substantive changes from previous issue.Even if the measures described above to prevent lossof leak-tight integrity are followed, small leaks may stilloccur as a result of structural failure or other unfcresetnevents. For example, equipment failures in systemsconnected to the pool could result in loss of water fromthe pool if such loss is not prevented by design. Apermanent fuel-pool-coolant makeup system with amoderate capability, and with suitable redundancy orbackup, could prevent the fuel from being uncovered ifI I IUSNRC REGULATORY GUIDESRegutlatory Guides are issued to describ. and make Available to the Publicmalthods accopthble to the NRC %talf of implementing specific pensl OL theCommntision s regulations, to delineate techniques used by the stall in Ovltueting speciitc problems or postulated accidents, or to provide guidance to appli.cnlto. Regulatory Guides ate not substitute* for regulations. and compliancewith them is not required Methods and solutions different from those set out inthe guides will be acceptable it they provide a basie for the findings requisite to, thd isluAnCe or continuance of a permit or license by the CommistionDemrents and suggestions fo, inmprovements ,n these guides are encouragedt alt times, and guides will be tevised. as AppOoprrate. to accommodate cornemals and to retlect new inoormation or emper.ence H*owever. cOmments onthis guide, of received within about two months Alter ilt issuance. will be par,titcilarly usetul in evaluating the need lot .n early revisiontComments should be sent to the Secretary of the Commission, U.S. NuclearRegulatory Commission, Washington. D.C. 205. Attentionm Doclsting andService Section.The guides ate issued in the following ton broad divisions1 Power Reactors2. Research and Test ReactorsJ. Fuels end Materials Fi-cilities4. Eneronmental and SitingS Materials and Plant Protection6 Product*7. Transportation8, Occupational Health9 Antitrust Reviewto GeneralCopies of published guides may be obtained by wrraten request indicating thedivisions desitrd to the U S Nuclear Regulatory Commission. Washington. D C.2M,. Attention Oirector. Oltice of Staedards Development such leaks should occur. Early detection of pool leakageand fuel damage could be provided by pool-water-levelmonitors and radiation monitors designed to alarm bothlocally and in a continuously manned location. Timelyoperation of building filtration systems can be assuredby actuating these systems by a signal from localradiation monitors.2. Mechanical Damage to FuelThe release of radioactive material from fuel mayoccur during the refueling process, and at other times, asa result of fuel-cladding failures or mechanical damagecaused by the dropping of fuel elements or the droppingof objects onto fuel elements.Missiles generated by high winds can also be apotential cause of mechanical damage to fuel. Designingthe fuel storage facility to prevent such missiles fromcontacting the fuel would eliminate this concern.A relatively small amount of mechanical damage tothe fuel might cause significant offiite doses if no dosereduction features are provided. Use of a controlledleakage building surrounding the fNel storage pool, withassociated capability to limit releases of radioactivematerial resulting from a refueling accident, appearsfeasible and would do much to eliminate this concern.

C. REGULATORY POSITION

I. The spent fuel storage facility (including itsstructures and equipment except as noted in paragraph 6below) should be designed to Category I seismic require-ments.2. The facility should be designed (a) to keep tor-nadic winds and missiles generated by these winds fromcausing significant loss of watertight integrity of the fuelstorage pool and (b) to keep missiles generated byI tornadic winds from contacting fuel within the pool..3. Interlocks should be provided to prevent cranesfrom passing over stored fuel (or near stored fuel in amanner such that if a crane failed, the load could tipover on stored fuel) when fuel handling is not inprogress. During fuel handling operations, the interlocksmay be bypassed and administrative control used toprevent the crane from carrying loads that are notnecessary for fuel handling over the stored fuel or otherprohibited areas. The facility should be designed tominimize the need for bypassing such interlocks.4. A controlled leakage building should enclose thefuel pool. The building should be equipped with anappropriate ventilation and filtration system to limit thepotential release of radioactive iodine and other radio-active materials. The building need not be designed towithstand extremely high winds, but leakage should besuitably controlled during refueling operations. Thedesign of the ventilation and filtration system should bebased on the assumption that the cladding of all of thefuel rods in one fuel bundle might be breached. Theinventory of radioactive materials available for leakagefrom the building should be based on the assumptionsgiven in Regulatory Guide 1.25, "Assumptions Used forEvaluating the Potential Radiological Consequences of aFuel Handling Accident in the Fuel Handling andStorage Facility for Boiling and Pressurized WaterReactors" (Safety Guide 25).5. The spent fuel storage facility should have at leastone of the following provisions with respect to thehandling of heavy loads, including the refueling cask:a. Cranes capable of carrying heavy loads shouldbe prevented, preferably by design rather than byinterlocks, from moving into the vicinity of the pool; orb. Cranes should be designed to provide sirgle-.failure-proof handling of heavy loads, so that a singlefailure will not result in loss of capability of thecrane-handling system to perform its safety function; or-c. The fuel pool should be designed to withstand,without leakage that could uncover the fuel, the impactof the heaviest load to be carried by the crane from themaximum height to which it can be lifted. If thisapproach is used, design provisions should be made toprevent the crane, when carrying heavy loads, frommoving in the vicinity of stored fuel.6. Drains, permanently connected mechanical orhydraulic systems, and other features that by malopera-tion or failure, could cause loss of coolant that woulauncover fuel should not be installed or included in thedesign. Systems for maintaining water quality andquantity should be designed so that any maloperation orfailure of such systems (including failures resulting fromthe Safe Shutdown Earthquake) will not cause fuel to bejuncovered. These systems need not otherwise meetCategory I seismic requirements.7. Reliable and frequently tested monitoring equip-ment should be provided to alarm both locally and in acontinuously manned- location if the water level in thefuel storage pool falls below a predetermined level or ifhigh local-radiation levels are experienced. The high-radiation-level instrumenttation should also actuate thefiltration system.8. A seismic Category I makeup system should beprovided to add coolant to the pool. Appropriateredundancy or a backup system for filling the pool froma reliable source, such as a lake, river, or onsite seismicCategory I water-storage facility, should be provided. Ifa backup system is used, it need not be a permanentlyinst.lled system. The capacity of the makeup systemsshould be such that water can be supplied at a ratel011.13-2 determined by consideration of the leakage rate that

D. IMPLEMENTATION

would be expected as the result of damage to the fuelstorage pool from the dropping of loads, from earth- Any of the alternatives in Regulatory Position C.5 ofquakes, or from missiles originating in high winds.* Revision I may be applied at the option of applicantsfor construction perinits and operating licenses for all*The staff is considering the development of additional guidance plants, regardless of the date of application.concerning protection against missiles that might be generatedby plant failures such as turbine failures. For the present, theprotection of the fuel pool against such missiles will beevaluated on a case-by-case basis.1.13-3