Safe disposal of spent nuclear fuel

Spent nuclear fuel can be converted into a new ceramic wasteform, SYNROC-F, which consists of a pyrochlore-type phase CaUTi//2O//7, hollandite Ba(Al, Ti)//2**3** plus Ti//6**4** plus O//1//6 and rutile, approximately 90:5:5 wt%, and has a spent fuel-loading of approx. 50%. Partition experiments show that the large cations e. g. Cs, Ba are immobilized in hollandite, whilst the pyrochlore phase is host to Sr, rare earths, and uranium. SYNROC-F is fabricated using the same technology currently utilized for SYNROC-C. It is much more resistant to leaching and groundwater attack than untreated spent fuel, moreover its constituent phases are analogous to natural minerals which have survived in a variety of geochemical conditions for millions of years. Because of its continued integrity at high temperatures, SYNROC-F can be buried without the costly and complex canisters and overpacking necessary for the direct disposal of spent fuel, and does not require intermediate surface storage. Furthermore, it can be buried irretrievably in widely scattered deep drill-holes, a disposal strategy which offers reduced environmental hazards and negligible risks of proliferation.