Swelling of microstructure of neutron-irradiated titanium-modified type 316 stainless steel

The analysis of the behavior of fuel pins irradiated in the same Rapsodie subassembly, shows that titanium has a marked beneficial effect on the swelling resistance of cold-worked Type 316 stainless steel in a wide temperature range. This effect is particularly visible at high temperature since cold-worked Type 316 titanium does not swell above 5500C up to a dose of 100 French displacements per atom (dpa F)( about74 dpa NRT). The results obtained on samples irradiated in a Rapsodie experimental rig give us confirmation of the good behavior of cold-worked Type 316 titanium stainless steel that swells less and at lower temperature than other steels of the Type 316 series such as solution-annealed Type 316 titanium or aged solution-annealed Type 316 titanium. The swelling differences between some of these materials can be associated with different microstructures that are also very different from the ones obtained on the unirradiated steels aged for the same time and temperature conditions