is because the heat generated during the curing of the epoxy resin is radiated through the yoke made of iron this suggests that a resin which exhibits a temperature rise to 100 u00b0 c or lower when allowed to cure alone cannot cause a temperature rise to a level higher than 60 u00b0 c when allowed to cure in a magnet coupling ring and hence does not cause any unfavorable effect on the characteristics of the magnet the magnet pump of the present invention having a magnet coupling described hereinbefore can suitably be used in the coolant circulation system of a nuclear reactor equipment offering advantages such as prevention of leakage of liquid having u03b3 rays and easy and safe periodical inspection the magnet pump of the invention when the magnets of the magnetic coupling is of neodymium iron type magnet can suitably be used in the coolant circulation system for circulating coolant carrying neutron beams in such a case the pump offers an advantage that the degradation of the magnet due to irradiation with the neutron beams is avoided in addition to the above mentioned advantages a description will be given of a practical example of the invention referring to fig2 pieces of magnetized magnet of neodymium iron type each being 34 mm wide 25 mm long and 10 mm thick were bonded to the outer peripheral surface of an inner ring yoke of 228 mm diameter and 150 mm long then a non magnetic cylindrical cover of hastelloy of 1 mm thick was bonded by plasma welding to the inner ring yoke the inner ring yoke was beforehand provided with eight resin.