Radioactive waste disposal bentonite

Radioactive waste disposal facilities are investigated for constmction in deep strata 50-1000m under the ground [1-5]. As shown in Fig. 2, the use of clayey materials such as bentonite, and cementitious materials, such as concrete and... 

We have developed and improved the numerical code THAMES to predict and assess the coupled THM behaviour in and around the EBS of the geological disposal of high-level radioactive waste. THAMES is a finite element code for analysis of coupled thermal, hydraulic and mechanical behaviour of a saturated-unsaturated medium. Then, we applied THAMES to calculate this task of the DECOVALEX III. In this task, the evolutions and the distributions of stress, relative humidity and temperature at the specified points in bentonite buffer material are required. 

The engineered barriers are composed of vitrified waste encapsulated in a canister, metal overpack and buffer material in a geological disposal system of high-level radioactive waste (HLW) adopted by INC (2000). Highly compacted bentonite is considered as the candidate buffer material for the system. Figure I shows the schematic view of the geological disposal system and expected processes after emplacement of the engineered barriers. 

Proposals for the geological disposal of heat emitting high-level radioactive wastes (HLW) have been put forward by many countries including Japan, Canada, Sweden, Switzeriand, USA, Spain and others. The disposal concepts invariably involve underground multi-barrier schemes where bentonite clay is chosen for a number of desirable attributes including its swelling potential and ability to trap the majority of released radionuclides (JNC 1999 Chapman and McCombie 2003). 

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