Plant Surfaces - doe-std-1128-98

DOE-STD-1128-98

4.2.1 Plant Surfaces

Good housekeeping practices are essential in keeping plant surfaces clean. Periodic

housekeeping should be performed within contaminated areas to minimize the

buildup of contamination and contaminated waste. Periodic decontamination both

within contaminated glove boxes and in the general work area should be conducted to

minimize removable contamination.

In some instances, it may be appropriate to apply fixatives to minimize the movement

of plutonium contamination. However, it is generally desirable to attempt

decontamination first. If decontaminating is not successful or perhaps, not

appropriate for the job scope, a fixative may be appropriate. If a fixative is used,

typically a paint, two layers of fixative should be used, with the bottom coat yellow

and the top coat a different color. When the yellow begins to show through the top

coat, additional fixative should be applied. Also, for areas which have had a fixative

applied over plutonium contamination, a routine contamination survey should be

conducted to assure that no contamination has become movable over time.

In some cases a strippable coating may be used to allow easy decontamination at the

completion of a job. These strippable coatings are sometimes used to decontaminate

areas. An aerosol fixative is also available that can be pumped into a room, glovebox,

or other work space, that coats all exposed surfaces, including the underside of

components. This allows work to proceed without disturbing contamination.

Note: The use of fixatives may require the approval of Facility Criticality Safety

personnel because fixatives may concentrate or moderate fissionable material.

Outside areas may also require a fixative to minimize the spread of contamination.

Historically, some outside contaminated areas have been covered with asphalt to fix

contamination. This is not a desirable material to use because it creates a mixed

hazardous waste as well as significantly increasing the volume of contaminated

material for disposal. Two substances that currently are used as an interim fixative

for outside soil/surface contamination areas are (1) a derivative of pine tar (toll oil),

which forms a non-toxic surface fixative that is hard and appears to have a relatively

durable surface and (2) a mixture of white glue and water (enduro seal), which is

easily sprayed on and sets rapidly to a firm surface. A water to glue ratio of about 25

to 1 appears to perform well in preliminary tests. Both of these fixatives are only

interim measures because of eventual degradation from the elements. For more

localized areas where a permanent fixative/cover is needed, a sprayable concrete

(Shotcrete) is available. A disadvantage of this material is cracking, which defeats the

sealing surface. Another material that can be used as a carpeting for outside

contamination is a spray-on two-part polymer that provides a flexible, semidurable

cover.

4-7