Patent Number: 
Section: claims

1. A device designed to be used for neutron imaging immersed in a medium containing specimens to be analyzed, comprising: a first converter comprising a first material capable of converting thermal neutron radiation into remnant beta radiation by its neutron activation and a second converter comprising a second material capable of absorbing thermal neutron radiation by capture and capable of converting a remnant beta radiation into light radiation, said second converter being in contact with said first converter, andfurther comprising a support comprising hydrogenated species on which said second converter is positioned, said support being transparent to said light radiation. 2. The device designed to be used in neutron imaging as claimed in claim 1, wherein the first material comprises dysprosium. 3. The device designed to be used in neutron imaging as claimed in claim 1, wherein said second converter comprises a scintillator material which is a compound containing gadolinium, which can be of the type (Tb doped) Gd2O2S. 4. The device designed to be used in neutron imaging as claimed in claim 3, wherein the scintillator material is mixed with an organic binder. 5. The device designed to be used in neutron imaging as claimed in claim 1, wherein the thickness of the first converter is of the order of a hundred microns. 6. The device designed to be used in neutron imaging as claimed in claim 1, wherein the thickness of the second converter is of the of the order of ten microns. 7. The device designed to be used in neutron imaging as claimed in claim 1, wherein the support comprises a transparent material, with hydrogenated species, of the polymethylmethacrylate type, where said support can have a thickness of the order of a few millimeters. 8. A leak-tight system designed to be used in neutron imaging immersed in a medium comprising a device as claimed in claim 1 and a vessel leak-tight to said medium, incorporating the first converter, the second converter, and the support. 9. A method for neutron imaging immersed in a medium and using a system as claimed in claim 8, comprising:immersing said system in a liquid medium comprising specimens to be analyzed;irradiating said system by a flux of neutrons;removing said system from said liquid medium;removing said converters from said leak-tight vessel; andrecording of the scintillation generated by the second converter. 10. The neutron imaging method as claimed in claim 9, wherein the specimens to be analyzed are nuclear fuels.