Device for detecting radioactivity in a liquid metal coolant

Object: To considerably increase efficiency of neutron detection and at the same time, to facilitate maintenance and checking and to increase safety. Structure: A neutron detection system is provided in the outer periphery of a dual pipe line which extends upwardly from a cylinder type induction system magnet pump so that when a fissionable product is contained in the flowing coolant, a neutron released from said fissionable product is detected by the neutron detection system. In this case, the neutron detection system is mounted so as to surround the dual pipe line portion and can detect most of neutrons released over the range of 360 degrees. Since the neutron detection system and a coil in the cylinder type induction magnet pump are insertably mounted in the outer periphery of the dual pipe line portion wherein the coolant is flown from an outer passage towards an inner passage in a part of a piping line through which coolant flows, they can be merely pulled out and new ones may be fitted, in case of replacement. (Kawakami, Y.)