LBLOCA Analysis of OPR1000 with Deployment of Severe Accident Tolerable SiC Fuel Cladding

Abstract

Since the Fukushima Daiichi nuclear power plant accident in 2011, replacement of current zircaloy fuel cladding with severe accident tolerable cladding materials has been invoked to mitigate potential severe accidents. A strong candidate is silicon carbide (SiC), which is chemically inert and makes little reaction with various reactor coolants. Melting point of SiC is exceptionally high enough (~2500 K) to resist any kind of thermal attack. SiC is also known as an effective moderator in the thermal reactor applications. Therefore the deployment SiC as a fuel cladding is expected to bring many advantages as compared to the current zircaloy cladding. In order to realize the aforementioned advantages, many research efforts have been made in the nuclear engineering fields. Meanwhile, it is of interest to see a possible thermal-hydraulic performance of the SiC tube hypothesizing the full length application for the light water reactor such as Optimized Power Reactor 1000 MWe (OPR1000) operating in Korea. As a preliminary study, LBLOCA analysis of the OPR1000 were conducted using a system safety code, MARS-KS by simply replacing the current zircaloy cladding with SiC without changing cladding dimensions. A simple approach of maintaining same thermal-hydraulic configurations of current OPR1000 was adopted. Instead, up-to-date thermo-physical properties of SiC were adopted from Snead et al.'s study. It is shown that at the initiation of the LBLOCA, blowdown peak cladding temperature (PCT) occurs within 10 seconds and the magnitude is about 1142 K. With SiC cladding, however, the blowdown PCT was reduced by as much as 68 K. In addition to the lower blowdown PCT, some reduction of reflood PCT with SiC tube was also observed, which suggests that adoption of SiC cladding will benefit in increasing the transient safety margin given the design basis accidents.