Regulatory Guide 1.13

Spent Fuel Storage Facility Design Basis,For Comment

ML003739943
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Issue date:	12/31/1975
From:	Office of Nuclear Regulatory Research
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RG-1.13, Rev 1
Download: ML003739943 (3)

U.S. NUCLEAR REGULATORY COMMISSION

REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.13 SPENT FUEL STORAGE FACILITY DESIGN BASIS

A. INTRODUCTION

General Desion C'riterinn A1

"Fuel

.

A

Revision 1 December 1975

1. Loss of Water from Storage Pool I

,

...

5d,,,,a anu Unless protective measures are taken, loss of water Handling Criteria for Nuclear Power Plants," of Appen- from a fuel storage pool could cause ove ting of the dix A, "General Design Criteria for Nuclear Power spent fuel and resultant damage to f ddg integ Plants," to 10 CFR Part 50, "Licensing of Production rity and could result in release of r

• oacti aterials to and Utilization Facilities," requires that fuel storage and the environment. Natural eve su as eav uakes or handling systems be designed to assure adequate safety th win t.

co ul eve as rectly or under normal and postulated accident conditions. It also high winds, could damage t

• ther directly or requires that these systems be designed with appropriate by the generation of s.

,q or high winds containment, confinement, and filtering systems and be could also cause stru e

an designed to prevent signifidant reduction in the coolant pool. Designing fa twithstand these occur inventory of the storage facility under accident condi- rences without of watertight integrity tions. This guide describes a method acceptable to the would all h

cerns.

NRC staff for implementing this criterion.

B. DISCUSSION

D

o eavy loads, such as a 1 00-ton fuel cask, IBin**

k~w probability, cannot be ruled out in plant nts where such loads are positioned or moved be designedmto:

that fuel handling and storage fac in over the fuel pool. Possible solutions to this b s dotential problem include (1) preventing, preferably by adesign rather than interlocks, heavy loads from being a. Prevent loss of water from the l.l lifted over the pool; (2) using a highly reliable handling would uncover fuel.

system 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

c. Provide the capa y

limiting the potential leakage from the pool area in which fuel is stored.

offsite exposures iieh gnificant release of radioactivity fro

.

Even if the measures described above to prevent loss

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tkof leak-tight integrity are followed, small leaks may still If spe el ag ecilities are not located within occur as a result of structural failure or other unforeseen the pri aiac t ontainment or provided with events. For example, equipment failures in systems adequate ective features, radioactive materials could connected to the pool could result in loss of water from be released the environs as a result of either loss of the pool if such loss is not prevented by design. A

water from the storage pool or mechanical damage to permanent fuel-pool-coolant makeup system with a fuel within the pool.

moderate capability, and with suitable redundancy or

• Lines indicate substantive changes from previous issue.

backup, could prevent the fuel from being uncovered if USNRC REGULATORY GUIDES

Comments should be sent... th c

Regulatory Guides are issued to describe and make available to the public methods acceptable to the NRC staff of implementing specific parts of the Commissions regulations, to delineate techniques used by the staff in evalu ating specific problems or postulated accidents, orto provide guidance to appli cents Regulatory Guides are not substitutes for regulations, and compliance with them is not required Methods and solutions different from those set out in the guides will be acceptable if they provide a basis for the findings requisite to the issuance or continuance of a permit or license by the Commission Comments and suggestions for improvements in these guides are encouraged at all times. and guides will be revised. as appropriate. to accommodate cow ments and to reflect new information or experience However, comments on Ihis guide. if received within about two months after its issuance, will be par iicularly useful in evaluating the need for an early revision e

.....................

,

lary o sne Commission. U.S. Nuclear Regulatory Commission. Washington. D.C. 2%56.

Attention: Docketing and Service Section, The guides are issued in the following ten broad divisions:

1. Power Reactors

2. Research and Test Reactors

3. -Fuels and Materials Facilities

4. Environmental and Siting

5. Materials and Plant Protection

6. Products

7. Transportation S. Occupational Health

9. Antitrust Review

10. General Copies of published guides may be obtained by written request indicating the divisions desired to the U.S. Nuclear Regulatory Commission. Washington. D.C.

20555. Attention: Director, Office of Standards Development.

such leaks should occur. Early detection of pool leakage and fiel 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 offsite doses if no dose reduction features are provided. Use of a controlled leakage building surrounding the fuel storage pool, with associated capability to limit releases of radioactive materiel resulting from a refueling *accident, appears feasible and would do much to eliminate this concern.

C. REGULATORY POSITION

1. 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.

I 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 single 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 would 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 bet 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 instrumentation 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 installed system. The capacity of the makeup systems should be such that water can be supplied at a rate

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 1 may be applied at the option of applicants for construction permits 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