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

COMMISSION

REGULATORY

GUIDE OFFICE OF STANDARDS

DEVELOPMENT

Revision 1 December 1975 REGULATORY

GUIDE 1.13 SPENT 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 water Handling Criteria for Nuclear Power Plants," of Appen- from a fuel storage pool could cause ove~htating of the dix 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 to and Utilzation Facilities," requires that fuel storage and the environment, Natural events as .a q or handling systemls be designed to assure adequate safety s..... coue aamage "uia ue or.... ... .. m~~hgh winds, coul damamge arcyo under 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 winds requires 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 noct designed 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 moved It is important that futel handling and storage i It di to: lin-r over the fuel pool. Possible solutions to this be designed to"potential problem include (1) preventing, preferably by a. Prevent lotdesign rather than interlocks, heavy loads from being a. P t lo lifted over the pool; (2) using a highly reliable handling would uncover fuel. sys:em designed to prevent dropping of heavy loads as a result of any single failure; or (3) designing the pool to b. Protect the fuel from mechanical damage. withstand dropping of the load without significant S. .... leakage from the pool area in which fuel is stored.I c. Provide the capa y .limiting the potential offsite exposures in the ificant release of radioactivity fro .If spe el rage cilities are not located within the priý a , ontainment or provided with adequate ective features, radioactive materials could be released the environs as a result of either loss of water from the storage pool or mechanical damage to fuel within the pool.'*Lines indicate substantive changes from previous issue.Even if the measures described above to prevent loss of leak-tight integrity are followed, small leaks may still occur as a result of structural failure or other unfcresetn events. For example, equipment failures in systems connected to the pool could result in loss of water from the pool if such loss is not prevented by design. A permanent fuel-pool-coolant makeup system with a moderate capability, and with suitable redundancy or backup, could prevent the fuel from being uncovered if I I I USNRC REGULATORY

GUIDES Regutlatory Guides are issued to describ. and make Available to the Public malthods accopthble to the NRC %talf of implementing specific pensl OL the Commntision s regulations, to delineate techniques used by the stall in Ovltu eting speciitc problems or postulated accidents, or to provide guidance to appli.cnlto. Regulatory Guides ate not substitute*

for regulations.

and compliance with them is not required Methods and solutions different from those set out in the 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 Commistion Demrents and suggestions fo, inmprovements ,n these guides are encouraged t alt times, and guides will be tevised. as AppOoprrate.

to accommodate corn emals and to retlect new inoormation or emper.ence H*owever.

cOmments on this guide, of received within about two months Alter ilt issuance.

will be par, titcilarly usetul in evaluating the need lot .n early revisiont Comments should be sent to the Secretary of the Commission, U.S. Nuclear Regulatory Commission, Washington.

D.C. 205. Attentionm Doclsting and Service Section.The guides ate issued in the following ton broad divisions 1 Power Reactors 2. Research and Test Reactors J. Fuels end Materials Fi-cilities

4. Eneronmental and Siting S Materials and Plant Protection

6 Product*

7. Transportation

8, Occupational Health 9 Antitrust Review to General Copies of published guides may be obtained by wrraten request indicating the divisions 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 leakage and fuel damage could be provided by pool-water-level monitors and radiation monitors designed to alarm both locally and in a continuously manned location.

Timely operation of building filtration systems can be assured by actuating these systems by a signal from local radiation monitors.2. Mechanical Damage to Fuel The release of radioactive material from fuel may occur during the refueling process, and at other times, as a result of fuel-cladding failures or mechanical damage caused by the dropping of fuel elements or the dropping of objects onto fuel elements.Missiles generated by high winds can also be a potential cause of mechanical damage to fuel. Designing the fuel storage facility to prevent such missiles from contacting the fuel would eliminate this concern.A relatively small amount of mechanical damage to the fuel might cause significant offiite doses if no dose reduction features are provided.

Use of a controlled leakage building surrounding the fNel storage pool, with associated capability to limit releases of radioactive material resulting from a refueling accident, appears feasible and would do much to eliminate this concern.C. REGULATORY

POSITION I. The spent fuel storage facility (including its structures and equipment except as noted in paragraph

6 below) 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 from causing significant loss of watertight integrity of the fuel storage pool and (b) to keep missiles generated by I tornadic winds from contacting fuel within the pool..3. Interlocks should be provided to prevent cranes from passing over stored fuel (or near stored fuel in a manner such that if a crane failed, the load could tip over on stored fuel) when fuel handling is not in progress.

During fuel handling operations, the interlocks may be bypassed and administrative control used to prevent the crane from carrying loads that are not necessary for fuel handling over the stored fuel or other prohibited areas. The facility should be designed to minimize the need for bypassing such interlocks.

4. A controlled leakage building should enclose the fuel pool. The building should be equipped with an appropriate ventilation and filtration system to limit the potential release of radioactive iodine and other radio-active materials.

The building need not be designed to withstand extremely high winds, but leakage should be suitably controlled during refueling operations.

The design of the ventilation and filtration system should be based on the assumption that the cladding of all of the fuel rods in one fuel bundle might be breached.

The inventory of radioactive materials available for leakage from the building should be based on the assumptions given in Regulatory Guide 1.25, "Assumptions Used for Evaluating the Potential Radiological Consequences of a Fuel Handling Accident in the Fuel Handling and Storage Facility for Boiling and Pressurized Water Reactors" (Safety Guide 25).5. The spent fuel storage facility should have at least one of the following provisions with respect to the handling of heavy loads, including the refueling cask: a. Cranes capable of carrying heavy loads should be prevented, preferably by design rather than by interlocks, from moving into the vicinity of the pool; or b. Cranes should be designed to provide sirgle-.failure-proof handling of heavy loads, so that a single failure will not result in loss of capability of the crane-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 impact of the heaviest load to be carried by the crane from the maximum height to which it can be lifted. If this approach is used, design provisions should be made to prevent the crane, when carrying heavy loads, from moving in the vicinity of stored fuel.6. Drains, permanently connected mechanical or hydraulic systems, and other features that by malopera-tion or failure, could cause loss of coolant that woula uncover fuel should not be installed or included in the design. Systems for maintaining water quality and quantity should be designed so that any maloperation or failure of such systems (including failures resulting from the Safe Shutdown Earthquake)

will not cause fuel to bej uncovered.

These systems need not otherwise meet Category I seismic requirements.

7. Reliable and frequently tested monitoring equip-ment should be provided to alarm both locally and in a continuously manned- location if the water level in the fuel storage pool falls below a predetermined level or if high local-radiation levels are experienced.

The high-radiation-level instrumenttation should also actuate the filtration system.8. A seismic Category I makeup system should be provided to add coolant to the pool. Appropriate redundancy or a backup system for filling the pool from a reliable source, such as a lake, river, or onsite seismic Category I water-storage facility, should be provided.

If a backup system is used, it need not be a permanently inst.lled system. The capacity of the makeup systems should be such that water can be supplied at a ratel 01 1.13-2 determined by consideration of the leakage rate that

D. IMPLEMENTATION

would be expected as the result of damage to the fuel storage pool from the dropping of loads, from earth- Any of the alternatives in Regulatory Position C.5 of quakes, or from missiles originating in high winds.* Revision I may be applied at the option of applicants for 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 generated by plant failures such as turbine failures.

For the present, the protection of the fuel pool against such missiles will be evaluated on a case-by-case basis.1.13-3