Enclosures (as primary confinement) cont'd

DOE-HDBK-1132-99

The following additional considerations should be addressed in designing

enclosures:

Where practical, equipment not functionally required to operate directly

in the presence of radioactive materials should be located outside the

enclosure. Equipment that must be located within the enclosure should

be designed to allow for in-place maintenance and/or replacement.

The design and operation of support and protection systems, such as

fire protection, should not promote the failure of the enclosure system

integrity or the loss of confinement.

Noncombustible or fire-resistant, corrosion-resistant materials should be

used for enclosures and, to the maximum extent practicable, for any

required radiation shielding. In no case should the total combustible

loading located in a fire area exceed the fire resistance rating of the

structural envelope. (See National Fire Protection Association (NFPA)

Fire Protection Handbook for guidance on the relationship of

combustible loading versus fire resistance rating.)

In conjunction with their ventilation systems, enclosures should be

capable of maintaining confinement (i.e., negative pressure with respect

to the surrounding operating area).

To reduce migration of contamination, closure devices or permanent

seals should be provided on entrances to and exits from piping, ducts, or

conduits penetrating confinement barriers. Such closures or seals

should have an integrity equal to or greater than the barrier itself.

Where pertinent to safety, enclosure design should consider heat

generation in the enclosure. Such heat sources may be from processes,

lighting, chemical reactions, and the decay of radioactive material.

Consideration of radioactive material as a heat source is particularly

applicable to storage enclosures.

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