METHOD FOR PRODUCING A CLADDING TUBE OF A FUEL ROD IN A PRESSURISED WATER REACTOR, A CLADDING TUBE AND A CORRESPONDING FUEL BUNDLE

摘要

The external surface of the fuel rod consists of a ZrNb alloy, which only forms a thin oxide layer with a thickness of Y = a • exp(b • A) that is devoid of cracks, even at a burn-up (A) of over 75 MWd/kg U. Secondary phases containing niobium, which are distributed over the core volume in the zirconium matrix, decrease the corrosion exponent (b). In addition, the ZrNb alloy is then thermally treated by quenching to remain consistently below 800 °C in such a way that for all subsequent treatment steps, the sum of all the recrystallisation parameters Xi = 1018 • ti • exp(-Q/nRTi), where (n = 1.9; Q/R = 80.000 K; ti = combustion duration in hours, Ti = combustion temperature in K), lies between 0.01h and 8h. Narrower limits can be calculated from the designated burn-up of the fuel rod.