Effect of helium production on swelling of F82H irradiated in HFIR

The effects of helium production and heat treatment on the swelling of F82H steel irradiated in the HFIR to 51 dpa have been investigated using 10B, 58Ni and 60Ni-doped specimens. The swelling of tempered F82H-std and F82H doped with 10B irradiated at 400°C ranged from 0.52% to 1.2%, while the swelling of the non-tempered F82H doped with 58Ni or 60Ni was less than 0.02%. At 300°C the swelling in all steels was insignificant. In the F82H + Ni, a high number of density carbides formed in the matrix at these temperatures. The production of helium atoms enhanced the swelling of the F82H steel. However, the non-tempered treatment for the F82H + Ni suppressed remarkably the swelling. The cause of low swelling in the F82H + Ni may be due to the occurrence of the high density of carbides acting as sinks or the decrease of mobility of vacancies interacting with carbon atoms in matrix.