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

6.67
Canisters
HLW 2,380
Cladding Hulls 2,300
End Fittings 1,520
Total 6,200
Cladding hulls and end fittings are not thermally hot. However, they would be handled in
the same manner as HLW for storage and disposal because of their high radiation levels and
the possibility of contamination by transuranic elements.
The shipping area of the port facilities would include a canister transfer pool and a
transfer cask storage area. To load the ship, the canisters would be moved from the cask and
transferred to the ship by crane. The dock facilities would accommodate two ships of the
class described below.
b. Seagoing Vessels. Because of the quantities of waste canisters to be disposed of,
subseabed disposal would require special dedicated ships (Bechtel 1979a). Each ship would
contain equipment for handling the canisters during loading, a water pool to store the can-
isters during transportation, the necessary equipment to emplace the canisters in the sedi-
ment, and water cooling and treatment facilities.
The waste ships could have double hulls and bottoms. Waste canisters would be secured in
the holds of the ships in basins filled with water. This concept of transporting fuel canis-
ters in a shipboard storage pool, while new, is considered entirely feasible and is assumed
for the reference study.
Disposal of spent fuel might require approximately 15 days to load a ship, 15 days for
the round trip from port to repository, and up to 50 days to emplace the canisters at the
subseabed site. Thus, a ship would make four trips a year. Based on transporting 1,275 can-
isters per trip, two ships would be required.
The sea-transportation requirements for HLW would be the same as those for spent fuel
assemblies. It is estimated that the same numbers and class of ships as described above
would be adequate for transporting HLW and cladding hulls. The same number of trips would be
required, but total turnaround time would be about 15 days less because fewer canisters would
be handled.
In addition to the ships used for the disposal operations, a survey ship would monitor
the emplacement of canisters and their positions relative to one another.
Emplacement. It is assumed that a free-fall penetrometer would provide one alternative
method for emplacing canisters in the seabed sediment (Bechtel 1979a). The canisters would
have a nose cone to aid penetration and tail fins for guidance. Alternatively, they might be
lowered to a predetermined depth and released, and would be designed to penetrate about 30
meters into the sediment. Laboratory tests indicate that the holes made as the canisters en-
tered the sediment would close spontaneously. Canister instrumentation would permit a moni-
toring crew to track each canister to ensure proper penetration into the sediment and spacing
between canisters.