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

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4.57<br />

4.4.2.2 Water Basin Storage <strong>of</strong> Solidified High-Level <strong>Waste</strong> (Example Method)<br />

Solidified high-level waste packages (described in Section 4.3.2) can be stored in<br />

water basins in much the same manner as that described in Section 4.4.1.1 for the water<br />

basin storage <strong>of</strong> spent fuel. In the facility for water basin storage <strong>of</strong> solidified high-<br />

level-waste examined here (see DOE/ET-0028, Section 5.4.1), the singly encapsulated (in<br />

stainless steel) waste is received for storage from an adjacent waste solidification<br />

facility. The waste canisters are stacked in double-tiered racks in water basins, each <strong>of</strong><br />

which is designed to hold the waste from reprocessing spent fuel containing 1,500 MTHM.<br />

Each basin is equipped with a water purification system and a heat exchanger system to<br />

remove the decay heat, which is dissipated to the atmosphere via a cooling tower. Eight<br />

such basins are included in the facility design. Radionuclide emissions estimated for water<br />

basin storage <strong>of</strong> vitrified high-level waste are given in Table 4.4.3.<br />

4.4.2.3 Sealed Cask Storage <strong>of</strong> Solidified High-Level <strong>Waste</strong><br />

The sealed storage cask concept for extended storage <strong>of</strong> solidified high-level waste<br />

involves encapsulating the waste canister in a high-integrity, sealed metal storage cask and<br />

then placing the doubly encapsulated waste in a reinforced concrete radiation shield. The<br />

assembly is then placed on a base in a large outdoor storage yard. Air circulates by<br />

natural convection between the radiation shield and the sealed cask to remove the heat being<br />

generated by the waste. This concept has been studied extensively (ARHCO 1976).<br />

A facility to implement this concept was designed to accommodate 0.3 x 3 m waste canis-<br />

ters generating about 4.4 kW <strong>of</strong> decay heat (see DOE/ET-0028, Section 5.4.2). The facility's<br />

initial capacity is 2,000 canisters <strong>of</strong> waste; it can be expanded in 2,000 canister modules<br />

to an ultimate capacity <strong>of</strong> 20,000 canisters.<br />

TABLE 4.4.3. Estimated Radionuclide Releases During Water Basin<br />

Storage <strong>of</strong> Vitrified High-Level <strong>Waste</strong><br />

Fraction( a ) Released Each<br />

Fission Products Year During Storage<br />

H 0<br />

Kr 0<br />

I 0<br />

Cs<br />

2 x 10 -13<br />

All Others<br />

2 x 10 -14<br />

Actinides<br />

U 1 x 10- 16<br />

Pu<br />

All Others<br />

1 x 10 -16<br />

2 x 10 -14<br />

(a) Fraction <strong>of</strong> activity in spent fuel<br />

released to atmosphere. See Table 4.2.4<br />

for the activity in spent fuel.

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