Measurement of fast neutron induced fission cross section of minor-actinide

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In fuel cycles with recycled actinide, core characteristics are largely influenced by minor actinide (MA:Np, Am, Cm). Accurate nuclear data of MA such as fission cross section are required to estimate the effect of MA with high accuracy.In this study fast neutron induced fission cross section of MA is measured using Dynamitron Accelerator in Tohoku University. The experimental method and the samples, which were developed or introduced during the last year, were improved in this fiscal year: (1)Development of a sealed fission chamber, (2)Intensification of Li neutron target, (3)Improvement of time-resolution of Time-of-flight (TOF) electronic circuit, (4)Introduction of Np237 samples with large sample mass and (5)Introduction of a U235 sample with high purity. Using these improved tools and samples, the fission cross section ratio of NP237 relative to U235 was measured between 5 to 100keV, and the fission cross section of Np237 was deduced. On the other hand, samples of Am241 and Am243 were obtained from Japan Atomic Energy Research Institute (JAERI) after investigating fission cross section of two americium isotopes (Am241 and Am243) which are important for core physics calculation of fast reactors.