The neutron nuclear data community in Japan wished to have a domestic evaluated nuclear data library in spite of the fact that many evaluated data libraries or files are available. The purpose of preparing JENDL is to meet the demands of national projects, to make a contribution to the international cooperation, and to develop the potentiality to improve the evaluated data.
Since 1970, evaluation work on nuclear data has gradually increased. This brought about a decision to start compilation of the first version of JENDL (JENDL-1) to include mainly the data of nuclides needed for the fast breeder reactors.
The data recommended to JENDL-1 are divided into five categories: 1) data recommended from working-group members of the JNDC through their own evaluation, 2) data recommended from the compilation group for JENDL-1 through their own evaluation, 3) data recommended through investigation of the existing evaluated data under a contract with JAERI, 4) data recommended through evaluation made by the persons in charge of evaluated data under a contract with JAERI, 5) the data of ENDF/B-IV recommended by persons in charge under a contract with JAERI.
Data of some quantities for almost all nuclides were estimated from the calculations with nuclear model codes. These quantities are background cross sections in the resonance region, inelastic scattering cross sections for each excited level of the residual nucleus, angular distributions of elastically scattered neutrons, and some of the threshold reaction cross sections.
The following nuclides were selected for JENDL-1 before starting the compilation work. The nuclides in parentheses were excluded because the ENDF/B-IV data for these nuclides were judged to be the best at that time. Therefore, the data of ENDF/B-IV are recommended for those nuclides when they are needed.
H, 6Li, (7Li,) 10B, (11B), 12C, (16O), 23Na, 27Al, Si, Cr, 50Cr, 52Cr, 53Cr, 54Cr, 55Mn, Fe, 54Fe, 56Fe, 58Fe, Ni, 58Ni, 60Ni, 61Ni, 62Ni, 64Ni, Cu, 63Cu, 65Cu, 90Sr, 93Zr, Mo, 92Mo, 94Mo, 95Mo, 96Mo, 97Mo, 98Mo, 100Mo, 99Tc, 101Ru, 102Ru, 104Ru, 106Ru, 103Rh, 105Pd, 107Pd, 109Ag, 129I, 131Xe, 133Cs, 135Cs, 137Cs, 144Ce, 143Nd, 144Nd, 145Nd, 147Pm, 147Sm, 149Sm, 151Sm, 153Eu, 181Ta, 232Th, 233Pa, 234U, 235U, 238U, 239Np, 239Pu, 240Pu, 241Pu, 241Am.