Pool Boiling Critical Heat Flux of Accident Tolerant Fuel Cladding Materials

摘要

The Fukushima Daiichi accident in Japan in 2011, initiated by a tsunami, has led to a global effort to develop more accident tolerant fuel (ATF) for light water reactors (LWRs) [1]. Currently, LWRs must accommodate design basis accidents (DBAs) with capabilities to maintain viable long-term cooling for an extended period of time even under beyond design basis accidents (BDBAs) [2].As a part of ATF program, the University of Wisconsin-Madison is investigating a variety of ATF cladding materials including Zirlo®, Cr coated Zirlo®, FeCrAl coated Zirlo®, and CVD (chemical vapor deposition) SiC. As a part of this larger study we are studying critical heat flux (CHF) limits of these cladding concepts in pool boiling conditions. For these studies, the cladding materials were first subjected to pressurized water corrosion environment to promote the formation of prototypical surface corrosion product layer that would form under normal reactor operating conditions. The samples were then tested in a pool boiling facility under atmospheric pressure conditions. Fig. 1 shows the schematic supersonic velocities onto the surface of a substrate (the cladding in this case) to form a coating. Surface roughness and morphology evaluations and contact angle measurements were performed to understand the CHF behavior of the ATF candidate coating materials.