Irradiation Creep Deformation of Modified 316 and 15Cr-20Ni Base Austenitic Fuel Elements Irradiated in FFTF

摘要

Irradiation creep of modified 316 (PNC316) and 15Cr-20Ni base austenitic stainless steels was determined using the diametral change of the fuel pins, which were irradiated under the fission gas pressurized condition in FFTF to a peak displacement damage of 107 dpa in PNC316 and 120 dpa in 15Cr-20Ni base. The creep compliance B_0 and creep-swelling coupling coefficient D were found to be 1.1 to3.0X10~(-6) MPa~(-1)dpa~(-1) and up to l.3 X 10~(-2) MPa~(-1) for instantaneous volumetric swelling rate, respectively. Those are almost the same level as those derived using the pressurized tubes irradiated in FFTF-MOTA. D values tend to decrease and disappear with developing void swelling.