| 摘要 |
<p>Process for making a tube-guide for a nuclear reactor, to guide a cluster of control rods carrying neutron-absorbing pencils which are lowered into the reactor to slow down the nuclear reaction, ensures that the control cluster can descend in the tube-guide and be lifted without friction and without undergoing blockage. The tube-guide comprises a lower part consisting of a sub-assembly of sleeves held together by positioning plates and an upper part consisting of guide-plates which define with the sleeves paths of descent for the neutron-absorbing pencils carried by a head. The upper and lower parts of the tube-guide are retained inside an envelope formed of two halves bent longitudinally at 90 degrees and joined. The envelope has holes on its periphery, at the site of each plate, arranged to receive with play points provided on the periphery of the plates. Process consists of placing the halves of the envelope enclosing the previously assembled and welded sub-assembly and the guide-plates in a cage formed of two half-shells and having ribs placed opposite the plates to support them. Expansile mandrels are introduced into the plates to press their four sides against the corresp. periphery of the ribs in the cage. The plates are then welded to the envelope by establishing a weld point between each point of the plate and its corresp. hole according to a programme to avoid tension effects in the tube-guide. The four-metre long tube guide can be assembled and welded so that all friction between the pencils and the guidage surface is eliminated.</p> |
