WEP045 　粒子源　 8月8日 大展示ホール 13:10 - 15:10

Feasibility of on-site nuclear material identification in Fukushima Daiichi fuel debris by X-band electron linac-based compact neutron source

○Yudhitya Kusumawati, Yuki Mitsuya (The University of Tokyo), Tomooki Shiba (Japan Atomic Energy Agency), Mitsuru Uesaka (The University of Tokyo)

Unaccountable nuclear fuel debris in reactor core area of Fukushima Daiichi became subject of safeguards and criticality safety, and mapping of nuclear debris activity through on-site screening is necessary to provide reliable data for debris removal plan. Screening activity consists of dual energy X-Ray CT and Neutron Resonance Transmission Analysis that complements each other, and the latter can identify isotopes in a material. By using compact pulsed neutron source constructed from 3.95 MeV X-Band electron linac, coupled with Tungsten as electron-to-photon converter and Beryllium as photon-to-neutron converter, short-distance neutron Time of Flight measurement can be performed. The measurement result of this system shows up to 100 eV neutron energy spectrum can be obtained from a 2.5-meter distance through Helium-3 neutron detector. Neutron resonance transmission experiment using Tungsten as dummy for Uranium shows that energy absorption in the resonance neutron area of Uranium-238 from 1-100 eV can be observed, as well as multiple elements detection. With its compact size and short Time of Flight path, this system can be implemented in on-site nuclear debris screening system.