Management of Commercially Generated Radioactive Waste - U.S. ...

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A similar approach was examined as an alternative for the storage of the waste packaged
in 55-gal drums that requires remote handling. In this instance 5 drums are stored in each
caisson (0.66 m dia x 5.2 m deep). Most of the drums can be unloaded from the shipping
container and placed in storage using only a shielded mobile yard crane that has a vacuum
lifting device. Drums having high surface dose rates are transferred to the caisson using
a bottom loading cask. In this design, 504 storage spaces are provided in each module.
4.4.3.3 Unshielded Indoor Storage of CH-TRU
The packages of TRU waste that can be contact-handled can be stored indoors in an
unshielded facility. A conceptual facility examined as an alternative to outdoor storage
consists of a precast concrete building containing a number of individual storage cells.
Drums (55-gal) are stacked six high in horizontal layers; plywood sheets are placed between
the layers. Steel boxes are also used to package such wastes; a storage box occupies the
space of 12 drums. The boxes and drums are handled by mobile cranes and by fork-lift
trucks.
The basic module used in this design includes two cells, each of which will store
4,200 drums. When storage capacity beyond that provided by the basic module is required,
an expanded version of the basic module is used or multiples of the basic module are
employed.
4.4.3.4 Outdoor Storage of CH-TRU (Example Method)
Outdoor storage is the example concept of this Statement for contact-handled TRU
wastes. This approach is presently used at most government installations. Several varia-
tions are in use, involving below-grade as well as above-grade techniques and differing
amounts of weather protection. The most widely accepted method is to place the waste pack-
ages on some structural pad, and cover them first with an impermeable membrane, and then
with dirt.
In this design the drums and boxes of waste are placed on an above-ground asphalt slab
that is contained within a temporary air-supported structure to allow operations to continue
during inclement weather. The containers are arranged in horizontal layers; sheets of ply-
wood are placed over each layer before the next layer is added. Handling of the containers
is by mobile crane and by a drum grabber. As the storage area is filled, polyethylene
sheets are placed over the stacked containers and the stack is covered with dirt to a depth
of at least 0.9 m. Once a storage area is completely filled and covered with earth, the
air-supported structure is removed, and the dirt cover is either seeded or covered with a
bitumen layer.
The basic storage module for this concept has a storage capacity for 10,000 55-gal
drums of waste. Capacity can be expanded by either using an expanded version of the basic
module or by using multiples of the module.