A study on the sodium leak accidents for the structural material in liquid metal reactor

LMR(Liquid Metal reactor) in many countries have made a lot of leak accidents during the operation over a long time. This problem is caused by the characteristics of the special operation condition such as the high operation temperature, the high neutron flux region and the sodium condition different from LWR(Light Water Reactor). This report has investigated the state of the leak accidents for the reactor types of LMR in many countries and arranged the causes and locations of the leak accidents. The most important cause of the leak accidents during the operation in LMR was the defects of the welds. This is because of that the residual stress existed in the welds make the welded structure occur the crack under the external small loading easily. The other important causes were the corrosion, fabrication defects and thermal fatigue. Also, the most frequent locations of the leaks were the circuits of the secondary system and the steam generator