Experiments and data evaluations on MA in Japan

Current experimental activities on the cross-section measurements of the (n,γ) reaction on minor actinide are carried out by JAEA, TIT, KURRI and Nagoya groups (using neutrons from reactors at JRR3 and JRR4 and pulsed neutrons from the 30 MV Linac at KURRI, as well as the Pelletron at TIT). New data of the (n,) reaction cross-sections on 237Np, 241Am and 243Am have been obtained at 1 < En < 100 eV with a 4π Ge spectrometer. The data were analyzed and a new result for the cross-section of 241Am(n,γ)242gAm at thermal energy (activation method) is in press - a Gd filter with a cut-off energy of 0.1 eV had been used to correct for a resonance at En = 0.3 eV. Progress with the new beam line at the J-PARC 3 GeV spallation neutron source and the installation of new measurement system for the (n,γ) reaction cross-section at the 4 MV Pelletron at JAEA were described. Beam commissioning at the J-PARC beam line will start in 2008, and the performance of the measurement system at the Pelletron was fully assessed. Work on the JENDL Actinide file (JENDL/AC) was outlined, and the file will be released in 2008. All data in JENDL-3.3 from Ac to Fm over a neutron energy from 10-5 eV to 20 MeV have been reviewed by means of a new nuclear reaction model code (CCONE). Consequently, almost all of the data in JENDL-3.3 were revised, based on available experimental data, new theoretical calculations, resonance parameters and cross-sections. Secondary spectra for all nuclides were calculated with the CCONE code, and the least-squares method (GMA code) was used for the evaluation of fission cross-sections