Uranium mining, milling, processing and fuel fabrication

FIGURE 1 | The nuclear fuel chain

MiningMilling

Conversion Enrichment

F ue l Fabrication

Reactor Use

Repro-cessing

StorageDisposal

Uranium Tailings Depleted Uranium U3O8

~VLLW ~LLW

Uranium Ore

Natural Uranium UF₆

Enriched Uranium UO₂

Uranium Fuel UOX

Spent Uranium Fuel Reprocessed Uranium U Nitrate Reprocessed Uranium UF6

RE-RepU UO2

Separated Plutonium PuO2 Depleted Uranium UO2

MOX Fuel RE-RepU Fuel

Decommissioning Waste LLW VLLW

Operational Waste ILW LLW

Spent RE-RepU Fuel

HLW

Depleted RE-RepU U3O8

Reprocessed Uranium U3O8 ~LLW

Spent Uranium Fuel

Vitrified Waste Structure Waste Process Waste Separated Plutonium PuO2 MOX Scrap Spent MOX

HLW

HLW

HLW ~ILW

HLW HLW ILW ILW

Source: WISE-Paris.

The waste that arises at these various stages can be gaseous, liquid or solid. For some forms of gaseous waste, for instance radon in underground uranium mines, measurements are rarely attempted, and management consists in reducing exposures rather than measuring or capturing existing levels, even though gases like radon are extremely harmful. In some cases, radioactivity is filtered out of exhaust gases and injected with liquid effluents into the sea, which is another form of reducing immediate exposure, without reducing toxicity at the source. Solid forms of waste are generally the most stable and easiest to manage, and a substantial aim in policy is therefore commonly to convert less stable waste forms into more manageable solid forms. For example, reprocessing of spent fuel produces a waste stream of boiling and radioactive nitric acid, which is then subject to evaporation and turned into a vitrified (glass) product.

Along the four stages of the nuclear fuel chain, a variety of waste types occur:

URANIUM MINING, MILLING, PROCESSING AND FUEL FABRICATION

An important waste and major health risk is radon gas in underground uranium mines. Radon gas is an alpha emitter and decays to solid polonium, which has similar characteristics. Another source of radioactivity from uranium mining of any kind is the persistent presence of uranium, which decays into radon, in mine tailings: waste heaps of discarded rock material from mining operations. These tailings take up very large volumes and can cause significant health problems, especially in developing countries, where management practices are sometimes poor. Because radon is released as a gas, it is not possible to directly capture it. The other stages of uranium processing (conversion, enrichment and fuel fabrication) produce very limited amounts of waste.