Investigation into the Influence of Microstructural Parameters of Fuel Pellets on Their Stability under the Effect of Thermal Shocks

摘要

The parameters of tests and the main results of investigations into the behavior of WER- and RBMK-type domestic fuel pellets under the effect of thermal shocks are investigated. Fine-grain pellets with a high level of closed porosity are shown to be more resistant to failure, which can appear in the pellets during startup and while maneuvering over the reactor power, as well as if there is cladding failure of the fuel cell. The pellet strength decreases as the grain size increases to >25 μm. The residual failure resistance of pellets simultaneously decreases, which leads to a loss in their integrity.