Facility for reactor irradiations of metals at 78 °K; dose and recovery curves of electrical resistivity

Abstract

A liquid nitrogen irradiation loop was installed at the Research Reactor of N.R.C. 'Democritus' in Athens. This facility allows to irradiate metals with fast neutrons at 78 °K, where the electrical resistivities of these metals can be measured during irradiation. The irradiation facility as well as the electrical resistivity measuring cryostat, which allows annealing of the samples in the temperature range of 78 to 650 °K, are described in this paper. The annealing spectra of neutron irradiated Cu, Ni, Al, Fe and Fe(Si, C) were measured in order to prove the performance of the system and to get new recovery data mainly in the high temperature range. The details of these spectra are discussed with more emphasis of the fine structure to be seen. Stage II of Cu and Ni shows four well separated sub-stages indicating a rather complex recovery process.