Study on the Effective Parameters for Increasing the Life Time and Efficiency of UO2 Fuel Pellets

Nuclear fission of uranium atoms starts when a nuclear pellet is placed into the rod and then inside the nuclear reactor. Thus, the number of the produced atoms would be more than those of fission uranium atoms. No problem exists with solid products, but the gas products following the swelling of the pellets enter the gap between the pellet and rod. This causes destruction of the rod and the reactor safety reduction. It is better to exit the rod from the reactor before the event. Attempts are made to increase the life time and the generated energy with nuclear pellets to achieve higher efficiency. For this purpose, after the identification of the obstacles, the efficiency of the nuclear fuel pellets is increased by some modifications. This work is a review of the world activities to identify the obstacles and solutions provided for modifying the nuclear fuel pellets. The results demonstrate that the most important features of a nuclear fuel influence on the life time and efficiency of UO2 feul pellets are the largeness of grains along with intergranular porosities with controlled size, good creep and thermal conductivity properties.