Management of High Level Wastes (HLW)

High Level Wastes are those wastes in which the temperature may rise significantly as a result of their radioactivity so that this factor has to be taken into account in the design of waste forms and storage or disposal facilities. Such wastes arise as the result of burning nuclear fuel in reactors, which typically involves the production of heat-generating minor actinides and fission products. A proportion of HLW is the heat generating waste that remains from the reprocessing of spent fuel. The industry standard for the treatment of such HLW liquors is to further concentrate by reduced pressure evaporation for interim storage in double contained stainless steel tanks. Such tanks are heavily shielded with multiple cooling and agitation systems. Direct disposal of spent fuel offers an alternative to reprocessing. A storage period of some 50 years is considered necessary to allow for heat dissipation and to take advantage from natural radioactive decay, thus simplifying future disposal. If direct disposal of spent nuclear fuel is the chosen management option, there is currently no HLW disposal facility in the world available to accept this material.