h i g h l i g h t s g r a p h i c a l a b s t r a c t Interaction tests are performed between U 0.7 Pu 0.3 O 2 fuel and Pb 0.45 Bi 0.55 liquid metal coolant. Oxygen concentration in liquid metal, stoichiometry of the MOX and interaction temperature are studied. No chemical reaction detected. Less than 0.01% to 0.65% of the pellets is released into the coolant depending to the conditions.
a b s t r a c tIn the frame of the MYRRHA reactor project, the interaction between fuel pellets and the reactor coolant is essential for safety evaluations, e.g. in case of a pin breach. Therefore, interaction tests between uraniumeplutonium mixed oxide (MOX) pellets and molten lead bismuth eutectic (LBE) have been performed and three parameters were studied, namely the interaction temperature (500 C and 800 C), the oxygen content in LBE and the stoichiometry of the MOX (U 0.7 Pu 0.3 O 2Àx and U 0.7 Pu 0.3 O 2.00 ). After 50 h of interaction in closed containers, the pellet integrity was preserved in all cases. Whatever the conditions, neither interaction compounds (crystalline or amorphous) nor lead and bismuth diffusion into the surface regions of the MOX pellets has been detected. In most of the conditions, actinide releases into LBE were very limited (in the range of 0.01e0.15 mg), with a homogeneous release of the different actinides present in the MOX. Detected values were significantly higher in the 800 C and low LBE oxygen content tests for both U 0.7 Pu 0.3 O 2Àx and U 0.7 Pu 0.3 O 2.00 , with 1e2 mg of actinide released in these conditions.