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AssigneeFramatome
InventorsAlain Blocquel, Joseph Lara
Estimating the term…
A method and device for removal of a specimen (30), especially a parallelepipedal specimen, from within the internal wall of the vessel of a nuclear reactor which is at the end of its service and whose core has previously been dismantled, but which retains a high residual radioactivity. A rotating platform (10) carrying tools (23, 24) for cutting out by electrical discharge is inserted into the vessel (1), maintained under protective water (7). A first electrode produces a recess in a direction perpendicular to the internal wall (21) of the vessel, delimiting the external contour of the specimen, and a second electrode cuts the rear of the latter to a specified depth, before the withdrawal thereof from the wall. The specimen thus obtained is then extracted from the vessel.
Method for the removal of at least one sample or specimen (30) of specified shape from within the wall (2) of a generally cylindrical nuclear reactor vessel (1) having a vertical axis and an open top (3) and being maintained under protective water (7), from an internal wall surface (21) of said vessel, said method comprising the steps of
Device for the removal of at least one sample or specimen (3) of specified shape from within the wall (2) of a generally cylindrical nuclear reactor vessel (1) having a vertical axis and an open top (3) and being maintained under protective water( 7), from an internal wall surface (21) of said vessel, said device comprising a support (9) for a rotating platform (1) provided with means (17) of immobilization with respect to the internal wall (21) of the vessel (1) in the vicinity of a zone from which the metal of the vessel is to be removed, a first tool (23) for machining by electrical discharge, said first tool comprising a first hollow electrode &27) of rectangular cross-section, carried by a positioning mandrel (26) adapted to impose on the electrode a forward or reverse movement perpendicular to the wall in order to create a continuous recess (31) delimiting, on four sides, the external contour of a parallelepipedal specimen (3), a second tool (24) for machining, also by electrical discharge, said second tool comprising a second plate-shaped electrode (28) comprising a rectangular central housing having dimensions equal to the dimensions of the transverse cross-section of the parallelepipedal specimen to be removed, said second electrode being carried by another positioning mandrel adapted to insert said second electrode into one of the sides of the recess created by said first electrode, then for displacing said second electrode perpendicular to the direction of its forward movement towards the side opposite the recess and then for withdrawing the specimen thus cut out with said second electrode, means associated with the rotating platform for successively indexing the position of the mandrels carrying said first and second electrodes with respect to the zone for removing the specimen, thereby permitting the release of one of the mandrels when the other actuates the displacements of the associated specimen, and means (43, 44) for withdrawing the cut-out specimen from the second electrode and extracting it from the vessel.
Device according to clam 2, wherein the rotating platform (10) rests plane on plane on said support (9), said support being displaced in the vessel (1) along the vertical axis (3) of said vessel and comprising means of immobilization opposite the zone for removing the specimen.
Dependencies are inferred from the claim text.