[2B03-05] Neutron Measurements

10:05 AM - 10:20 AM JST(1:05 AM - 1:20 AM UTC)

[2B03] Development of Directivity-Improved Neutron Detection Method

*Yasushi Nagumo¹, Katsunori Ueno¹, Takeshi Muramoto², Kenichi Otani², Junji Iwasa², Satoshi Okada² (1. Hitachi, 2. HGNE)

Keywords:

Fuel debris,Identification of nuclear fuel,Measurement for fast neutrons

In the fuel debris retrieval work at Fukushima Daiichi Nuclear Power Station, it is necessary to identify the position of nuclear fuel in the debris before the work to avoid the risk of recriticality. However, direct identification of the position is difficult in the current situation where the nature of the debris is not clear. Therefore, the method to measure fast neutrons from spontaneous fission of Cm-244 which is considered as an indicator of nuclear fuel has been developing. In the method, by arranging moderators in a specific direction to thermal neutron detectors, the position of the neutron source is identified. As a result of basic performance tests, it was possible to identify the position of the neutron source.