Tono Natural Analogue Project (TAP)

Ota, Kunio 

Tono Natural Analogue Project has been conducted for about two decades at the Tono uranium deposit, central Japan, which has demonstrated to date that uranium mineralisation has been preserved for over millions of years in the host sedimentary formation despite repeated uplift/burial, faulting and marine transgressions/regressions. A couple of key factors (eg sorption, redox-buffering reactions, permeability etc) for the long-term stability of the deposit have been identified. A new approach to developing improved SA models based on the geological history not only reproduce the observed uranium retardation, but can also be of sure in indicating the relevant geological factors. The persistence of geochemical anomaly over millions of years in the Tono area is certainly a good illustration of "site stability" and the site stability requirements for the Tono uranium deposit is considered as an analogy to those for a HLW repository in Japan.