Pressurized water reactor fuel assembly with a guide tube and method for producing the guide tube

摘要

A pressurized water reactor fuel assembly with a guide tube and a method for producing a guide tube for control elements are provided. Such guide tubes in pressurized water nuclear reactors which are composed of zirconium alloys (zircaloy-2 and zircaloy-4) show sharp radiation-induced growth in the axial direction at the commencement of their use in the reactor core. The sharp initial growth of the tubes is compensated by an inherent contraction of the tubes. For this purpose, the guide tubes are given internal stresses which are reduced by tube contraction as a result of a radiation-induced supply of energy. During production, guide tubes which are too short are first produced and subsequently lengthened by at least 0.3% to a final dimension in a last production step. In order to lengthen the tube, it may be stretched on a straightening bench.