Properties of steel in liquid sodium environment

An experimental sodium dual-circuit equipment was developed for the study of refractory steels designed for steam generators and valves of nuclear power plants with sodium cooled fast reactors; the equipment allows operation with a temperature drop in the main testing circuit. The equipment consists of the main circuit with a testing segment and a corrosion product absorber, and of an auxiliary purification circuit with a cool trap. The two circuits have a common storage tank, argon management and an evacuation system. The sodium flow rate in the area of measured samples is 1 m/s, the maximum temperature of sodium is 550 degC. Studied within the experimental programme were the thermodynamic aspects of the structural stability of carbide phases at increased temperature, during applied mechanical stress with the application of transport processes brought about by surface diffusion interaction with liquid sodium. Some results of the experiments are discussed, namely those which used samples of Cr2.25Mo1NiNb steel. Briefly outlined are the possibilities of applying the calculation model which was developed for the discussion and interpretation of obtained experimental results. (Z.M.). 9 figs., 3 refs