Neutronic performance of CANDU reactor fuelling with ThC 2 / 233 UC 2

233 U isotope is used as a booster fissile fuel material in the form of mixed ThC 2 / 233 UC 2 fuel in a Canada Deuterium Uranium (CANDU) fuel bundle in order to assure the initial criticality at startup. Three different fuel compositions have been used: (1) 97% ThC 2 +3% 233 UC 2 , (2) 98% ThC 2 +2% 233 UC 2 and (3) 99% ThC 2 +1% 233 UC 2 . The temporal variation of the criticality k ∞ and the burn‐up values of the reactor have been calculated by full‐power operation for a period of 20 years. The criticality starts by k ∞ =1.541, 1.355 and 0.995 for modes of (1), (2) and (3) fuel compositions, respectively. A sharp decrease in the criticality has been observed in the first 2 years as a consequence of rapid 233 U burnout fuelling with (1) and (2) modes. The criticality becomes quasi‐constant after the second year and remains above k ∞ ∼1.06 for 20 years. After the second year, the CANDU reactor begins to operate practically as a thorium burner. Very high burnup could be achieved with the same fuel materials (up to 500 000 MWday t −1 ), provided that the fuel rod claddings would be replaced periodically (after every 500 00 or 100 000 MWday t −1 ). The reactor criticality will be sufficient for fuelling with (1) and (2) modes until a great fraction of the thorium fuel is burnt up. This would reduce fuel fabrication costs and nuclear waste mass for final disposal per unit energy drastically. Copyright © 2010 John Wiley & Sons, Ltd.