Present status of our investigations for the development of high-temperature resistant activation detectors

Investigations have been carried out on the development of activation probes for fluence measurements in high-temperature reactor experiments, i.e. probes where the losses of the activated nuclide remain under 1% even at temperatures above 12000C and exposure periods of 200 days. It was found that probe systems are promising which consist of a high-temperature resistant alloy of the activation probe material with a metal at high solubility, clad in a capsule of a material of very low solubility. Out-of-pile experiments with probes of this type consisting of an (V-1%Co)-alloy welded at 14300C and after a heat treatment period of 104 days. In addition, some exploratory heat treatment experiments showed that SiC-coated (Al2O3 + CoO) particles may be suitable as high-temperature resistant activation probes up to 15000C