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

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but double-walled tanks have been built in recent years at both Hanford and Savannah River
to reduce the possibility of leakage of waste into the environment (DOE/EIS-0063 1980 and
DOE/EIS-0062 1980). The defense program wastes were neutralized before storage (by the
addition of hydroxides) and are stored in carbon steel tanks. The commercial wastes pro-
duced at the West Valley Plant in New York are also stored in this way. More recent plans
involve storage of acidic waste in stainless steel tanks. Such tanks have been built (but
not used) at the Barnwell Plant in South Carolina. The design concept here (see DOE/ET-
0028, Section 5.1) is similar to that used at Barnwell.
The tanks employ double containment, consisting of a primary stainless steel container
within a stainless steel liner. Both containers are supported by and encased in a rein-
forced concrete vault. The tanks in this design are 17 m (54 ft) in diameter and 6 m
(20 ft) high and have a net storage volume of 1140 m 3 (300,000 gal) with 10% freeboard.
Each such tank has the capacity to store the concentrated high-level liquid waste resulting
from reprocessing spent fuel containing 2000 MTHM. Seven tanks are required to provide
capacity for 5-yr storage of the high-level waste produced at a 2,000 MT fuel reprocessing
plant (four tanks filled, one filling, one emptying and one tank held as a spare). The
radioactive decay heat is removed by cooling water, which passes through coils installed in
the tanks; the heat is then dissipated via a cooling tower. The contents of the tank are
continuously mixed by airlift circulators and by ballast tanks that provide an intermittent
flushing action.
The tank off gases are treated to remove any volatilized iodine and particulate radio-
nuclides that might be entrained in the gas stream. Estimated radionuclide emissions are
given in Table 4.4.2.
TABLE 4.4.2. Estimated Radionuclide Releases During Tank
Storage of Liquid High-Level Waste
Fraction( a ) Released Each
Fission Products Year During Storage
H 8 x 10 -3
Kr 0
I 5 x 10 -7
Ru
All Others
Actinides
U
Pu
All Others
1 x 10 -12
1 x 10 -13
5 x 10- 16
5 x 10- 16
1 x 10 -13
(a) Fraction of activity in spent fuel
released to atmosphere. See Table 4.2.4
for the activity in spent fuel.