The future underwater Neutron Imaging System of the Jules Horowitz MTR: An equipment improving the scientific quality of irradiation programs

Standard NDE techniques used in support to the irradiation process on fuels and materials in a Material Test Reactor (MTR) comprise i) photonic imaging: gamma scanning and gamma tomography, X-ray imaging and X-ray tomography, and ii) neutron imaging: neutron radiography. Due to different interactions of photons and neutrons with matter, these examinations means are not sensitive to the same chemical elements or isotopes and consequently don't reveal the same details and don't provide the same information. Two identical underwater photonic imaging benches, coupling gamma scanning and X-tomography, will be installed respectively in the reactor pool and in the storage pool of the JHR, capable of welcoming and checking an irradiation device containing the experimental sample. An underwater neutron imaging bench will be also implanted in the reactor pool and will gamma-X tomography bench in hot cell in air will check samples after dismounting from the sample holder. As a complement of a previous paper more focussed on photonic imaging benches and presented at the IGORR 13 conference, this paper presents in details the Neutron Imaging System (NIS) of the JHR. After a reviewing of the scientific information for nuclear fuel programs specifically gained thanks to this bench, the scientific needs in the fuel domain will be developed (sample geometries, specification of performances...). After that, the characteristics and the integration issues of the system in the reactor pool will be detailed. A focus will be carried out on the design of a performing detection system. Simulation of images obtained on objects reproducing real sample configurations will be shown. Finally, other aspects linked to the bench operation and planning will conclude the paper