A new fast neutron scattering technique for local void fraction measurement in two-phase flow

A new non-intrusive fast neutron scattering technique for local void fraction distribution in two-phase flow is presented. The theory upon which the technique is based is discussed, illustrating the capabilities and limitations of the technique. Single scattering of neutrons is formulated into a set of non-linear equations relating the local void fraction distribution to measured neutron fluences at different energies and angles of scattering. The inverse problem of solving these equations to reconstruct phase distribution is explained and demonstrated with examples. The techniques used for measuring the fluence and energy of the scattering neutrons are outlined, and experimental measurements are shown. Simulations of the measurements are compared with actual data