The resource-renewable boiling water reactor (RBWR) has been proposed as an innovative boiling water reactor (BWR) that has the capability to burn transuranium elements (TRUs) using a multi-recycling process by hardening the neutron energy spectrum. In this paper, RBWR core configurations with flat radial power distribution are investigated. In general, flat distribution of the radial power will be achieved if fuel bundles with a relatively large amount of fissile nuclides are arranged in a relatively low neutron flux area except for the outermost region of the core. There are two design policies of fuel bundle arrangement for flat distribution of the radial power. One is scatter loading using the local neutron flux gradient area is intentionally produced by arranging fuel bundles. The other is zone loading using the overall neutron flux gradient due to a leakage of neutrons to the radially outer side of the reactor core. For RBWR, both loading policies are adopted in succession. First, zone loading is adopted in the outer region of the reactor core in the radial direction. The fresh fuel bundles that have a relatively large amount of fissile nuclides are arranged in the radial outer region. Scatter loading is also adopted in the inner region of the reactor core in the radial direction. The inner region is divided into several layer rings that consist of a bundle in the angular direction. Layer rings for 2nd, 3rd, and 4th cycle fuel are arranged adjacently to each other. The radial power distribution at the end of cycle (EOC) is calculated using the whole core transport calculation, and it is confirmed that the radial power of RBWR is distributed in flat shape to be applied to the combined fuel arrangement of scatter loading and zone loading.
