Preliminary thermal hydraulic analysis of various accident tolerant fuels and claddings for control rod ejection accidents in LWRs

The present study assesses the effect of various accident tolerant fuel (ATF) materials on thermal hydraulic behaviors of Light Water Reactors (LWRs) in a Reactivity-Initiated-Accident (RIA). The study focuses on the impact of ATF thermal physical properties and cladding boiling heat transfer enhancement. The results show that without the heat transfer enhancement, peak cladding temperature (PCT) can be reduced by the utilization of FeCrAl, SA3-PyC150-A and HNLS/ML-A claddings but peak fuel centerline temperature (PFCT) rises at the same time. However, the reverse situation happens to the utilization of UO2 + BeO and UO2 + SiC composite fuels. In addition, to identify the potential impact of nucleate and film boiling heat transfer coefficient and critical heat flux (CHF), a sensitivity analysis to these parameters is conducted. The results show PCT is particularly affected by CHF. PFCT can be reduced and heat transfer deterioration is eliminated by the application of 90UO2 + 10SiC assembled with all the three ATF claddings as well as 90UO2 + 10BeO assembled with HNLS/ML-A cladding when 10% boiling heat transfer enhancement is added.