Radiation resistant bolometers with Al2O3 and AlN substrates, anodized aluminium support frames, and improved electrical contacts

Recent work has been devoted to develop a simplified bolometer type device which would enable in-reactor testing of more radiation resistant substrates, meander materials, and electrical contacts. The bolometer configurations based on a thin sandwich structure, make possible more reliable electrical connections, as well as facilitating PIE. Different materials for use as the insulating support frame for the delicate sensor substrate have been examined. Initially machineable glass ceramic (MACOR) was considered, and trial supports fabricated to test different configurations and electrical contact designs, however the high boron content makes this material unsuitable for a nuclear environment. Similar support frames were then made from alumina, this being the perfect choice for the application. But alumina was rejected due to cost of machining and fragility. Finally support frames of anodized aluminium were tested. These gave more than adequate electrical insulation for operating temperatures up to at least 400 °C. Ionizing radiation at high temperature and dose has no effect on the sensor resistance values. Several prototypes are now awaiting final in-reactor (BR2) characterization at SCK-CEN, Mol.