Primary Confinement System

DOE-HDBK-1132-99

Primary Confinement System. The primary confinement system consists of

process systems equipment and the associated off-gas system. Process

equipment failures should not cause failure of the secondary confinement

system. Process equipment should operate under process conditions that

prevent or minimize the probability of explosive chemical reactions.

Secondary Confinement System. The secondary confinement system

consists of the process cell barriers and the ventilation systems associated with

the cells. Design should consider the following features:

Secondary confinement areas should be equipped with sensors that

detect abnormal releases of hazardous material from the primary

confinement boundary and provide appropriate alarms. Commensurate

with the potential hazard, the use of redundant sensors should be

considered.

Penetrations of the secondary confinement should have positive seals to

prevent the migration of contamination out of the secondary confinement

area.

The ventilation system should be designed to maintain a negative

differential pressure during the removal of cell covers and for normal in-

leakage at cell cover joints.

Process cells should be supplied with ventilation air from the building

ventilation system and with exhaust ventilation of sufficient capacity to

provide controlled ventilation flow as required in the event of a credible

breach in the secondary confinement barrier.

Pressure in the compartments should be negative with respect to the

building ventilation system.

I-32