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

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The storage yard is monitored to detect any radionuclide leakage from the storage
units. Radionuclide emissions are assumed to be negligible since leakage of the doubly
encapsulated waste is believed to be highly improbable. Canisters that do leak can be
retrieved and repackaged.
4.4.2.4 Other Solidified High-Level Waste Storage Concepts
Solidified high-level waste could be stored in an air-cooled vault facility similar to
that described in Section 4.4.1.3 for the storage of spent fuel. In fact, the conceptual
facility for spent fuel storage is an adaptation of a concept for storage of solidified
high-level waste (ARHCO 1976). Double containment of the radionuclides in the high-level
waste could be provided by overpacking the primary canister. The design for a solidified
waste facility would be tailored to the high-level waste canister size and heat generation
rate.
Dry well storage of solidified high-level waste could also be employed. This would
resemble the dry well storage of spent fuel described in Section 4.4.1.4. Well size and
spacing would be different for the solidified waste than for the spent fuel, depending on
waste canister size and heat generation rate. Double containment of the waste by overpack-
ing the primary canister could also be utilized for this storage concept.
4.4.3 TRU Waste Storage
The packages of treated TRU waste described in Section 4.3.1 for the once-through case
and in Section 4.3.3 for the reprocessing case could require storage for an interim period
before a repository is available.
The packaged wastes are considered in one of two categories depending on the radiation
level. Packages that have surface dose rates no higher than 200 millirem/hr are "contact-
handled," i.e., workers can handle them without extensive shielding. Packages with higher
surface dose rates require shielding and/or remote handling to protect operating personnel;
these packages are "remotely handled."
The TRU waste packages with the highest surface dose rates are the canisters containing
the fuel residues (the fuel hulls and hardware). Some disassembled failed equipment is also
assumed to be packaged in identical canisters. Two alternative interim-storage facility
concepts for these canisters are described here (see also DOE/ET-0028, Section 5.2): vault
storage and dry-well (near-surface) storage. The dry well concept is used as the example
method in this Statement.
Other remotely handled TRU wastes are packaged in steel 55-gal drums. Vault storage
and dry well storage facility concepts for these wastes are described here (see also
DOE/ET-0028, Section 5.3). Vault storage is used as the example method in this Statement.
The contact-handled wastes are packaged in steel boxes or drums. Unshielded indoor
storage and outdoor surface storage facility concepts are described for these wastes. The
outdoor surface storage concept is the example concept used in this Statement.