Breaches in the primary confinement barrier that cannot be totally avoided or
ruled out (e.g., due to glove or seal failure) should be compensated for by
providing adequate inflow of air or safe collection of spilled liquid. Occasional
breaches required for anticipated maintenance should be made only under
carefully controlled conditions. Primary confinement should provide for storage
of in-process material elsewhere, temporary alternative barriers, and adequate
inflow of air to provide contamination control.
The supply and exhaust ventilation system should be sized to maintain in-facility
radiation doses at levels as low as reasonably achievable (ALARA) in the event
of the largest credible breach. Process equipment and the process itself should
be designed to minimize the probability of fire, explosion, or corrosion that might
breach the confinement barrier. When handling pyrophoric forms (e.g., chips,
filings, dust) of materials in the confinement enclosure, the guidance of DOE-
HDBK-1081, Primer on Spontaneous Heating and Pyrophoricity, should be
considered. Halon systems should not be used with pyrophoric metals due to
the oxidizing reaction between halon and hot metal.
Primary confinement barrier(s) should be provided between the process material
and any auxiliary system (e.g., a cooling system) to minimize risk of material
transfer to an unsafe location or introduction of an undesirable medium into the
process area. Differential pressure across the barrier(s) should be used where
The effectiveness of each confinement barrier should be checked analytically
against challenges it is expected to withstand without loss of function. This
applies to any form of the hazardous material (gas, liquid, or solid) and its
carrying medium (i.e., airborne or spilled in a liquid).
To protect the integrity of process confinement systems, fire protection systems
should include the following features:
Automatic and redundant fire detection devices.
A fire-extinguishing system that actuates automatically to--