Improvements in fission product detection systems

摘要

818,685. Nuclear reactors. PLESSEY CO. Ltd. Nov. 1, 1957 [Nov. 5, 1956], No. 33744/56. Class 39(4). Apparatus for determining the fission product content of a gas, comprises means for precipitating fission products from the gas onto a solid surface, means for permitting a continuous flow of the gas through the precipitation means, a beta ray counter device, and means for transporting the solid surface from the precipitating means to the counter device and vice versa. In Fig. 1 gas, which may be the coolant gas of a nuclear reactor, is passed via an inlet 6 and outlet 7 through a precipitation chamber wherein such of the gaseous fission product as decay to solid particles are deposited on a rod 8 under the influence of an electric field maintained between the rod 8 and the outer electrode 3 of the precipitation chamber. After exposure for a given time the rod 8 may be withdrawn by an actuator 2 so that the exposed part is placed adjacent an annular proportional counter 9 where its activity is measured ; the rod can then be moved back to the position shown in Fig. 1 for a further precipitation period, the count obtained during this period being used as a measure of the background radiation.