An effect of heavy water in a Korean DEMO water cooled ceramic blanket (WCCB)

A conceptual design study for Korean DEMO Reactor (K-DEMO) based on the Korean Fusion Energy Development Promotion Law (FEDPL) enacted in 2007 is now in progress. The K-DEMO at the first stage in our development plan is not regarded as a final DEMO but rather a test facility for a commercial reactor. The target of a preliminary blanket concept design study at the first stage is to promote the performance of breeding blanket in preference to any other. A preliminary blanket concept under consideration in the K-DEMO is based on a water-cooled ceramic blanket with lithium orthosilicate (Li4SiO4) as breeder, beryllium (Be) as neutron multiplier, and reduced activation ferritic-martensitic (RAFM) steel as structural material. To investigate the possibility of utilization of heavy water (D2O) as a coolant of a breeding blanket for the K-DEMO, a comparative study of the two coolants, D2O and H2O has been conducted. Furthermore, the dependence of tritium breeding ratio (TBR) on volume ratios of water and breeder occupying a blanket, and the impact of D2O replacing H2O as a coolant on the K-DEMO blanket have also been investigated with the calculations on the basis of the Monte Carlo simulation MCNPX code. This paper presents the results of comparative study of the two coolants, D2O and H2O on our preliminary blanket concept for the K-DEMO.