Studies of the Microstructural Origins of PWR Fuel Assembly Growth: The Effect of Tensile Stress on Irradiation Defect Formation in Zircaloy-4

摘要

Heavy ion irradiation with in-situ TEM was applied to simulate neutron damage in the Zry-4. It was shown that all main parameters of the neutron irradiation-induced damage structures could be produced with heavy ion irradiation under the chosen conditions. In addition, the effect of external stress on -loop formation in Zry-4 was investigated by irradiation of 5 samples of different initial stress levels. For the two samples at highest initial stress level, 100 % and 75 % of the yield strength, it was found that there is a clear effect of the c-compo-nent of the initial stress on the - loop formation within the individual samples. The -loop density decreased with increasing positive deviatoric stress component in the c-direction. For the sample at 100 % yield strength level, -loop formation was significantly delayed for the two grains with their c-axes at 11° and 13° to the stress direction: Loop densities close to zero were observed at the high dose level where the comparable grains with a different grain orientation towards the c-axis showed the expected high -loop densities.