Nuclear Technology / Volume 168 / Number 2 / November 2009 / Pages 264-269
Neutron Data / Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (Part 2) / Decontamination/Decommissioning
Large spallation sources are intended to be constructed in Europe (EURISOL nuclear physics facility and European Spallation Source). These facilities accumulate more than 20 tonnes of irradiated mercury in the target, which has to be treated as highly radioactive and chemotoxic waste. Because solids are the only appropriate (immobile) form for this radiotoxic and toxic type of waste, solidification is required for irradiated mercury. Our irradiation experimental studies on mercury waste revealed that mercury sulfide is a reasonable solid for disposal and shows larger stability in assumed accidents with water ingress in a repository compared to amalgams. For preparation of mercury sulfide, a wet process is more suitable than a dry one. It is easier to perform under hot cell conditions and allows complete Hg conversion. Embedding HgS in a cementitious matrix increases its stability.