Abstract: An arrangement for forming an optical image of the interior of an enclosure contained within a radiation shield the enclosure being one in which remote handling operations are carried out on radioactive material and the shield having a passage therethrough from an outer end to an inner end at the said enclosure, which arrangement includes at or adjacent to the inner end of the passage optical guiding means for guiding optical radiation from scenes within the enclosure along a path through the said passage, located at or adjacent to the outer end of the passage deflection means for deflecting optical radiation which has been guided along the said path and a photodetector arranged outside the shielded enclosure and outside the radiation shield to receive optical radiation which has been deflected by the deflection means.

Abstract: A fluid receptacle is provided with a retainer on the inner surface thereof for confining at least the reactive portion of a coated insert matrix within the receptacle during inversion thereof. The insert has a configuration permitting fluid to be poured into the receptacle and decanted from the receptacle by inversion of the receptacle with the reactive portion of the insert confined therein. The various decanting, washing and measuring operations involved in an assay may therefore be performed while the insert remains confined within the original receptacle, eliminating the need for additional receptacles and for manual assembly or disassembly operations during the assay.