their ventilation systems. Tertiary or final confinement should be the building
structure and its ventilation system.
Primary Confinement System. UEU cladding or storage containers typically
provide primary confinement during normal operation, anticipated operational
occurrences, and accidents. Cladding or storage containers are used to provide
a corrosion-resistant confinement for the fuel assemblies and other UEU to
prevent an uncontrolled release of radioactive material. Special design features
should be considered to introduce, remove, and handle UEU safely. These
handling systems and equipment should protect against the dropping of storage
containers, UEU assemblies, and other items onto the stored UEU.
Secondary Confinement System. The compartments and their ventilation
systems comprise the secondary confinement system. Penetrations of the
secondary confinement barrier should have positive seals to prevent the
migration of contamination. The use of positive seals should be considered for
penetration of enclosures within the facility building to provide proper ventilation
flow paths and to prevent the migration of contamination within the facility.
The need for special ventilation systems for confinement purposes should be
determined based on the safety analysis. In general, each compartment should
be supplied with ventilation air from the building ventilation system. Separate
exhaust ventilation should be 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 ventilation system
comprise the tertiary confinement system. Penetrations of the building
confinement barriers should have positive seals to prevent the migration of
Uranium Processing and Handling Facilities. The following provisions are
typical for a uranium processing and handling facility (UPHF) confinement