Quality Assurance and Quality Control in Fabrication of Cladding Tubes

摘要

Zircaloy 2 and 4 are the most important Zirconium alloys for use as fuel cladding material in light and heavy water reactors. In fast breeder reactors the cladding tubes are of a modified 16/16 - Cr-Ni-type with improved mechanical, long - term creep rate and rupture - life versus temperature properties. Starting with hot-extruded tube shells the fabrication of Zircaloy cladding tubes is done by 3 - 4 cold reduction steps in tube reducers or rolling machines followed by heat treatments in vacuum. To obtain the specified properties a precise combination of final area reduction and final annealing is absolutely necessary. The fabrication route of stainless steel claddings and guide tubes is similar to the Zircaloy production, exceptionally the last cold-forming steps are made on cold-drawing henches, hecause of economic reasons. After each cold reduction the material is annealed at recrystalisation temperatures under protective atmosoheres. For obtaining the same final tube properties for a longer nroduction neriod the implementation of a quality assurance and control system naturally independent of the production is necessary. The application of this system regarding some of the important properties of fuel cladding tubes is reported. (Atomindex citation 14:746683)