Confinement Devices - Continued - STD-1128-98master0322

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

Each glove box should be equipped with an audible alarm that can be tripped to

signal radiological problems. Individuals should be able to activate the alarm

without removing their arms from the glove box. The alarm should sound in a

continuously occupied area where it should, as a minimum, identify the room in

which the alarm originated.

A HEPA filter should be installed on the air inlet to the glove box if required to

prevent the backflow of contamination. Prefilters should be installed upstream of

the HEPA filter where appropriate. The exhaust outlet for each glove box should

have HEPA filters to keep the ventilation ductwork clean. This filter should not be

counted as a formal HEPA stage and need not meet all the test capabilities for

HEPA filtration; however, it should be tested prior to installation. Push-through

filter change-out systems should be used if possible. The HEPA filters downstream

of the glove box should be readily accessible for filter change-out and testable.

Glove-box air inlets and inlet filters should be protected or oriented to prevent

inadvertent entry of water into the box (e.g., a fire-sprinkler system discharge or

water-line leak).

Glove boxes should be designed to operate at a negative pressure (0.75 0.25 in.

water gage (WG)) with respect to the room in which they are operated. Differential

pressure gauges should be installed on each glove box or integrally connected

series of glove boxes. During abnormal conditions, control devices to prevent

excessive pressure or vacuum should be either positive-acting or automatic or both.

The ventilation system should be designed to provide and maintain the design

negative pressure during normal operations and the design flow through a breach.

There should be exhaust capacity on demand that will promptly cause an inflow of

air greater than 125 linear ft/min through a breach of at least a single glove-box

penetration of the largest size possible. Filters, scrubbers, demisters, and other

air-cleaning devices should be provided to reduce the quantities of toxic or noxious

gases and airborne particulates that enter the ventilation system prior to its entry

into the exhaust system.

Each glove box or integrally connected series of glove boxes should be equipped

with an audible alarm that alerts personnel when a system pressure or vacuum loss

is occurring. The alarm should be set at -0.5-in. WG relative to the room in which

the glove box is located.

The number of penetrations for glove-box services should be minimized. The

fittings should provide a positive seal to prevent the migration of radioactive

material. For the same reason, penetrations for rotating shafts should not be

permitted except where rotating shafts have seals. Seals for rotating shafts are very

reliable and are preferred to motors inside the glove box.

Vacuum systems connected to a glove-box should be designed to prevent an

evacuation and possible implosion of the glove box.

Any gas-supply system connected directly to a glove box should be designed to

prevent pressurization, flow in excess of the exhaust capacity, and backflow.

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