Confinement - STD-1128-98master0311

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

further enhance equipment reliability, the emergency equipment should, to the extent

practicable, be the same equipment used for routine operations.

Emergency-power requirements that need to be satisfied and the means to provide the power

should be identified in the design effort.

Emergency radiological equipment should be installed or located in areas that permit

periodic inspection, testing, calibration, and maintenance.

Additional emergency-preparedness guidance is provided in Section 9.0.

C.2.2 Confinement

The confinement system is a series of physical barriers that, together with a ventilation

system, minimizes the potential for release of radioactive material into work areas and the

environment under normal and abnormal conditions. The primary design objective for the

confinement system should be to minimize exposure of the public and plant personnel to

airborne contamination. Plutonium should be separated from the ambient environment by at

least two barriers and from an operator by at least one barrier.

Primary confinement refers to the barrier that is or can be directly exposed to plutonium,

e.g., sealed process equipment (pipes, tanks, hoppers), glove boxes, confinement boxes,

open-faced hoods, conveyors, caissons, and cells and their ventilation systems. The primary

confinement barrier prevents the dispersion of plutonium through either sealed construction

or atmospheric pressure differential or a combination of both. For example, process

equipment that is not sealed but contains plutonium material in process should be enclosed

in glove boxes or other confinement barriers. Fuel-rod cladding, bags, and other sealed

containers can be considered primary confinement. The chemical reactivity and the heat-

generation effect of the plutonium compound should be considered when selecting primary

confinement material.

The primary confinement barrier protects operators from contamination under normal

operating conditions. This type of barrier is likely to be breached under accident conditions

(e.g., glove rupture, damaged seals, improper bag-out operations, or leaks of flanged joints).

The primary confinement (with the exceptions of fuel rods, sealed sources, or sealed cans)

should be maintained at a negative air pressure with respect to the secondary confinement in

which it is located, and it should be exhausted through a ventilation system that uses HEPA

filters. The barrier and its accessory equipment should be designed to prevent accidental

flooding. All primary confinement piping joints should be tested for leak tightness.

Penetrations in the primary confinement barrier, such as conduit, ports, ducts, pipes, and

windows, should be protected against the release of radioactive material.

Where necessary, recycle ventilation systems may be used in process enclosures, hot cells,

and canyons. Inert gas systems should be designed as recycle systems, unless it is

impracticable to do so. Recycled inert gas systems should be maintained completely within

the primary barrier system. Extreme caution should be exercised in the use of recycle

systems for contaminated or potentially contaminated air. A recirculation system should not

direct air to an area where the actual or potential contamination is less than the area from

which the air originated. The decision to use a recirculation system in a contaminated area

C-5