BURST CARTRIDGE DETECTION - A STUDY OF MIXING IN A CALDER CHANNEL

摘要

If the gaseous fission products associated with can failure are not fully mixed with the coolant, a low concentration at the sampling hole could make the damage less sensitive to detection. To investigate this effect, nitrous oxide was injected into the air flow in a model Calder channel and then detected downstream with an infra-red gas analyser. Mixing along the fuel elements was found to be slow, and the distribution by no means complete even after half the length of a channel, but this is largely compensated by good mixing between the end of the top fuel element and the sampling position. In the worst case, when failure occurs near the outlet end of a channel, the sensitivity may be reduced by a factor of 2. This is unlikely to have a serious effect on efficiency of detection.