Keywords:Pressurized Water Reactor, Fast Breeding Reactor, Tightly Packed Fuel Assembly
The concept of PWR type breeding core with tightly packed fuel assembly for decreasing a moderator to fuel volume ratio is investigated. MOX, depleted uranium and Enriched uranium fuel is used. The breeding PWR core which has short compound system doubling time (CSDT) and meet the provisional criteria of minimum departure from nuclear boiling ratio (MDNBR) and negative void reactivity is investigated. This concept is developed with coupled neutronics and thermal-hydraulics core calculations. The neutronics calculation are carried out using SRAC2006, ASMBURN and COREBN codes, which are based on a collision probability method, a macroscopic cross section interpolation method and a neutron diffusion approximation. The thermal-hydraulics calculation consists of the single channel analysis of the maximum and the average power channel. The results indicate relationship between the power density increase to decrease CSDT and the pressure loss increase by core flow rate increase to meet the MDNBR criteria. Furthermore, changing blanket fuel from depleted uranium to enriched uranium is found to be effective to significantly reduce CSDT to less than 100 years.