The selective removal of halide fission products from an aquecus solution by exchange with the halide in solid silver halide has been studied as the basis for a fuel-element leak detector. The retention of fission-product halides on a silver halide column was investigated as a function of coolant flow rate, halide anion, arid column size. Fission-product decontamination factors and predicted operating lifetimes were obtained for a number of reactor operating conditions. It was concluded that a

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... ensitive, rapid leak detector for a water-cooled reactor could be constructed from a silver bromide or iodide column monitored by a neutron detector to detect delayed neutrons from the halide fission products. The feasibility of gross gamma monitoring is dependent upon the intensity of the gamma background arising from absorbed fission products on the silver halide column. The equilibrium value of this background can be determined only through in-pile experiments. The discovery of a fuel-element failure is generally based on the detection of one or more fission products in the reactor coolant following a failure. In a typical leakdetection system, a volume of the coolant or some constituent in the coolant is isolated and the radioactivity is measured to determine if failure has occurred. Among the systems which have been proposed are those which measure gross gamma activity!^ ^'^/""j, delayed neutronsCl^^), or high-energy beta particlesC^) in an isolated volume of the coolant. These systems generally have poor sensitivity when used in water-cooled reactors since activation of the coolant and corrosion products yields a high counting background. The background may be lowered by permitting the short-lived coolant radioisotopes to decay before radioassay of the coolant, but this technique undesirably delays the detection of a fuel-element rupture. ^Refeiences at the end.