Abstract: A method is provided for the quantitative determination of fissile material content in small size particles present in samples. The samples are sandwiched in organic sheets and then submitted to a defined thermal neutron fluence whereupon fission products of the fissile material in the sample create in the sheets fission tracks which are rendered visible by etching the sheets. Then the size of selected particles having created such tracks is. determined by means of a microscope and thereafter these visible tracks of the selected particles are compared to pre-established standard tracks obtained by the same process from particles of different stepped known size and enrichment ratio.

Abstract: The device disclosed comprises a high-pressure autoclave in which a moulded blank of the sample is heated by means of laser beams to the melting point and then rapidly cooled. The sample is maintained in a processing position (2) in an autoclave (1) without contact by means of an acoustic levitation device (12). Laser beams are directed through windows (19) in the autoclave onto the processing position and heat the sample. The molten sample then passes between two mutually impacting dies (20,21) by which it is crushed and thus rapidly cooled.