Unirradiated Enriched Uranium Storage Facilities

DOE-HDBK-1132-99

The need for special ventilation systems for confinement purposes should be

based on results of the safety analysis. In general, each compartment should

be supplied with ventilation air from the building ventilation system. Each

compartment should also be provided with separate exhaust ventilation handled

by a system with sufficient capacity to provide adequate ventilation flow in the

event of a credible breach in the compartment confinement barrier. Pressure in

the compartments should be negative with respect to the building ventilation

system.

Tertiary Confinement System. The facility building and its ventilation system

comprise the tertiary confinement system. Penetrations of the building

confinement barriers should have positive seals to prevent the migration of

contamination. Air locks or enclosed vestibules should also be provided for

access through confinement barriers.

1.2.2

Unirradiated Enriched Uranium Storage Facilities. The following provisions

are typical for an unirradiated enriched uranium storage facility (UEUSF)

confinement system. The actual confinement system requirements for a

specific UEUSF should be determined on a case-by-case basis.

The degree of confinement required is generally based on the most restrictive

hazards anticipated. Therefore, the type, quantity, and form (physical and

chemical) of the materials to be stored should be considered. For materials in a

form not readily dispersible, a single confinement barrier may be sufficient.

However, for more readily dispersible materials, such as liquids and powders,

and for materials with inherent dispersal mechanisms, such as pressurized

cases and pyrophoric forms, multiple confinement barriers should be

considered.

Generally, for the most restrictive case anticipated, the use of three confinement

systems should be considered. The primary confinement should be the

unirradiated enriched uranium (UEU) cladding or the storage container (e.g.,

canning). Secondary confinement should be established by compartments with

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