The Protected Plutonium Production (P 3 ) project has been initiated. The first stage of this project (P 3 -A) is based on the idea of protecting plutonium by 238 Pu isotope generated from 237 Np doped in the fresh uranium fuel. The present status of nuclear data relevant to the P 3 -concept reactor design is surveyed and data requirement is presented. + Present address: Engineering Development Co., Ltd., 3-1, Minatomirai 3-chome, Nishi-ku Yokohama 220-8401 Japan