2017 | AFC ACCOMPLISHMENTS 117 fuel coolant interaction) is not a credible scenario for any deployed nuclear reactor technology, though dispersal of high temperature fuel particulate is of interest for accident progression involving high burnup fuels. In transient testing such as will be performed at the Transient Reactor Test (TREAT) facility, FCI events represent the limiting condi- tion for experiment-induced loading on experiment containments.This research intends to renew expertise and develop analytic capabilities to evaluate FCI and possible thermal- mechanical energy conversion. Project Description: Fuel-coolant interactions (FCI) play a critical role in the safety evaluations of nuclear systems and have been the subject of considerable research, including beyond the nuclear industry. FCI events occur when cladding fails allowing direct interac- tion of fuel and coolant.With an extremely large temperature gradient driver, FCI may result in highly energetic behavior with rapid pres- surization and thermal-to-mechanical energy conversion.This research is focused on developing technical expertise and analytic tools to eval- uate FCI behaviors. For the purposes of this discussion, FCI events in nuclear systems are classified as the result of two different power-to- cooling mismatch conditions: (1) rapid, high energy overpower events (reactivity initiated accident) with possible cladding failure resulting in fuel dispersed directly into a range of coolant conditions; and (2) loss of sufficient cooling (loss of coolant accident) leading to cladding failures and possible fuel dispersal. In the most severe propagation of events, fuel melting and molten fuel coolant interaction (MFCI) may occur.The primary focus of this research is developing a capability required to design and perform transient The potential for energetic interaction between fuel ejected at high temperature and the surrounding coolant is a critical fuel safety issue and that has evaded effective analytical treatment for 50 years.