Recent progress in research and development on the neutron resonance densitometry for particle-like debris of melted fuel

Harada, Hideo   ; Kitatani, Fumito  ; Koizumi, Mitsuo ; Tsuchiya, Harufumi ; Takamine, Jun ; Kureta, Masatoshi   ; Iimura, Hideki  ; Seya, Michio; Becker, B.*; Kopecky, S.*; Mondelaers, W.*; Schillebeeckx, P.*

Neutron resonance densitometry (NRD) has been proposed to quantify nuclear materials in particle-like debris of melted fuel formed in severe accidents of nuclear reactors such as Fukushima Daiichi Nuclear Power Plants. NRD is a method combining NRTA (neutron resonance transmission analysis) and NRCA (neutron resonance capture analysis). It relies on neutron TOF (time of flight) technique using a pulsed white neutron source. The use of a special -ray spectrometer for NRCA and an evaluation of the achievable accuracy are discussed. The discussion is based on results of Monte Carlo simulations combined experimental data from measurements carried out at GELINA. In this contribution, progress made in the development of NRD for the characterization of nuclear materials mixed with highly radioactive nuclides is presented, together with the basic concept and principles.