In-pile and post-irradiation creep of type 304 stainless steel under different neutron spectra

In addition to post-irradiation creep tests, in-pile creep tests were perfo rmed using newly developed technology with in situ measurement under differ ent neutron spectra. The in-pile creep properties of type 304 stainless ste el at 550 degreesC appear to depend on neutron spectrum, but a spectral eff ect on post-irradiation creep properties is not clearly seen. The rupture t ime of in-pile creep under a high thermal neutron flux condition is the sho rtest. The order of the rupture time following the high thermal flux condit ion is post-irradiation creep, in-pile creep with a thermal neutron shield condition and finally creep of unirradiated material, all in increasing ord er. It is suggested that the acceleration of creep deformation and fracture observed in irradiation creep tests may be related to enhancement of therm al creep in terms of FMD increased under a high thermal neutron flux in add ition to increased helium embrittlement. (C) 2000 Elsevier Science B.V. All rights reserved.