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