Patent Number: 053944488
Section: summary

FIELD OF THE INVENTION The invention relates to a method and device for processing elements activated by irradiation, and in particular fuel element jackets of a nuclear reactor of the graphite/gas type with a view to their removal. BACKGROUND OF THE INVENTION Nuclear reactors of the graphite/gas type, which are moderated by graphite and cooled by carbon dioxide gas, comprise fuel elements arranged in graphite jackets of tubular shape, comprising, at one of their ends, stainless steel wires which are implanted in the thickness of the graphite jacket and are mutually perpendicular. The stainless steel wires, "saddle wires", are intended to hold a graphite part termed the "saddle" in the central part of the jacket. After a certain length of use inside the core of the nuclear reactor, the fuel element jackets must be removed and replaced. Because of their time spent in the core of the nuclear reactor, the jackets are activated, so that it is necessary to take certain precautions to dispose of them. Although the graphite of the jackets is moderately activated, the same is not true of the stainless steel constituting the wires, which has very high activity because of the nature of its constituents. It is therefore desirable, in order to dispose of the jackets for fuel elements under satisfactory conditions, to separate the graphite from the stainless steel wires, so as to store and dispose of the two constituents of the jackets for fuel elements separately. One of the factors making it possible to facilitate separation of the graphite and of the stainless steel wires is that the stainless steel of the wires is a magnetic steel and that graphite is non-magnetic. To date no method and device are known which make it possible to process such jackets for fuel elements, with a view to their disposal, automatically and efficiently. More generally, no method and device are known which make it possible to process and dispose of activated elements comprising two constituents having substantially different magnetic characteristics and activation levels which are also different. SUMMARY OF THE INVENTION It is therefore an object of the invention to provide a method for processing elements activated by irradiation with a view to their removal, the activated elements comprising two constituents having different magnetic a first, one of the constituents, having high activity and the or second constituent having a substantially lower activity, this method making it possible to separate and store the two constituents of the activated elements separately, in an efficient and completely automatic manner. For this purpose: the activated elements are ground to obtain unit fragments, each consisting mainly of the first or of the second constituent, PA1 the fragments consisting mainly of the first constituent are separated and sent by magnetic means to a first discharge or packaging station, and the fragments consisting mainly of the second constituent are separated and sent by magnetic means towards a continuous handling means, PA1 detection by radioactivity measurement of the fragments consisting mainly of the first constituent is carried out on the continuous handling means, PA1 the fragments deposited on the continuous handling means are removed to a second discharge and storage station if no fragment of the first constituent is detected on the continuous handling means, and towards the first discharge and packaging station if at least one fragment of the first constituent is detected on the continuous handling means. PA1 a grinding mill, PA1 means for removing the product in divided form at the output of the grinding mill, PA1 a magnetic separator having an input part communicating with the removal means of the grinding mill in order to feed it and two output paths for the product in divided form, PA1 a first storage means into which a first output path of the separator emerges, PA1 a continuous handling means with two directions of motion, comprising a first end arranged below the second output path of the separator and above the first packaging means, PA1 a radioactivity detector arranged in proximity to the continuous handling means, and PA1 a second storage and removal means arranged below a second end of the continuous handling means to receive the divided products discharged by the continuous handling means in a first direction of motion. The invention also relates to a device for processing elements activated by irradiation, with a view to their disposal, comprising: