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

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6.143<br />

<strong>Waste</strong> Form. The waste form would have to be a nondispersible, chemically stable solid.<br />

The composition <strong>of</strong> this waste has not been defined by the space program sponsors, but there<br />

are several possible candidate processes that might produce the proper form, as suggested in<br />

Figure 6.1.22.<br />

The waste form should contribute to overall system safety, especially for potential ac-<br />

cident sequences, and should also contribute to system optimization in terms <strong>of</strong> payload, ec-<br />

onomics, and materials compatibility. Desirable attributes are:<br />

* High HLW to inert content ratio<br />

* High thermal conductivity<br />

* Resistance to thermal shock<br />

* Thermochemical stability<br />

* Toughness<br />

* Low leachability<br />

* Applicable to both commercial and defense wastes<br />

* Resistance to oxidation<br />

e Low cost<br />

* Ease <strong>of</strong> fabrication.<br />

Because weight would be important in the launching operation, the waste forms should also<br />

maximize the amount <strong>of</strong> waste carried at each launch (waste loading). An iron/nickel-based<br />

cermet prepared by ORNL for other disposal options appears suitable, but would require<br />

further development.<br />

<strong>Waste</strong> Package. The reference waste package would consist <strong>of</strong> the spherical waste form<br />

surrounded by a metal cladding, a gamma shield, a steel honeycomb structure (for impact),<br />

insulation (for reentry), a graphite shield (for reentry), and the reentry vehicle itself,<br />

which would contain the waste during launch and Earth orbit in case <strong>of</strong> accident. Only conceptual<br />

definitions have been developed.<br />

<strong>Waste</strong> Partitioning. Certain space option alternative concepts would be enhanced if<br />

specific isotopes were removed from the waste, e.g., strontium or cesium. Alternatively,<br />

space disposal might be more appropriate for certain species, e.g., iodine, technetium, the<br />

actinides, or all three. Technology development would be needed to provide these partition-<br />

ing options.<br />

Facilities. The size, capacity, and functional requirements <strong>of</strong> the nuclear payload<br />

preparation facility are not defined. Major design tasks remain before this facility could<br />

be developed.

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