Development of fuel failure detection system for a high temperature gas cooled reactor. III

Part II reference unavailable. A precision-type precipitator has been developed for high-sensitivity detection of fuel failure in a high-temperature gas-cooled reactor. The fuel failure detection (FFD) method is based on selective detection of short-life fission products to eliminate the background effect caused by long-life fission products in the primary circuit. Although this precipitator has a limited length of wire in the body equal to that of the conventional type, it can control the movement of the wire precisely, preventing the collection of fission products on the same part of the wire in each round. Unlike the conventional type, the precision precipitator can greatly reduce the background counts of the precipitation wire. This is very effective for selective detection of short-life fission products in the primary coolant helium gas. Tests showed background counts from 10% to below 0.4%. Therefore, an extremely slight change in the amount of fission products released from coated particles can be detected by the FFD system at a failure rate of 10^-5