Special features (e.g., air locks, enclosed vestibules) should be
considered for access through secondary and tertiary confinement
Tertiary Confinement System. The process building and associated
ventilation system comprise the tertiary confinement system. Penetrations of
the building confinement barriers should have positive seals to prevent the
migration of contamination.
Uranium Conversion and Recovery Facilities (UCRFs). To the extent
practical, the primary confinement system should be constructed of fire-resistant
materials, and the process equipment and process being confined should be
designed to prevent potential flammable or explosive conditions. Confinement
enclosures for flammable metals should be designed with self-contained fire
protection and extinguishing equipment; in some cases, inert atmospheres may
be desirable within the enclosures.
Work that could subject personnel to possible inhalation exposures should be
performed in process confinement enclosures. Gloveboxes should be the
preferred enclosure, but are not always practical. Alternative systems may have
to be considered.
When gloveboxes are used, their design and construction should allow
replacement of parts and/or relocation of the box(es) within the facility or
system(s) with a minimum of contamination or exposure.
To the extent practical, discrete processing steps should be performed in
individual process confinements to reduce the amount of hazardous material
that can be released by a single or local failure of the confinement system.
Process and auxiliary system differential pressure should be maintained to
inhibit backflow of hazardous materials into auxiliary systems.