Guide tubes for pressurized water reactor fuel assemblies with minimized radiation-induced growth and associated manufacturing process

摘要

The invention concerns guide tubes (6) for zirconium alloy control elements (zircaloy-2 and zircaloy-4) in pressurized water nuclear reactors, said guide tubes displaying intense radiation-induced growth in the axial direction at the beginning of their use in the reactor core. The intense initial growth of the tubes is compensated by the inherent contraction of the tubes. To that end, guide tubes (6) are proposed whose internal stresses can be reduced by pipe contraction owing to the radiation-induced delivery of energy. In order to produce such tubes, a guide tube (6) which is too short is first produced and is then lengthened by at least 0.3 % to its final dimension in a final production step. In order to lengthen the tube, the invention proposes in particular stretching on a straightening bench.