Method of cleaning metal sodium handling equipment

Purpose: To clean and remove metal sodium in a short time from a metal sodium handling equipment. Method: Since the temperature rise due to the generation of heat upon reaction of steams and metal sodium has to be maintained at such a lower temperature usually about less than 100degC in view of the corrosion of material, the amount of the steams supplied is kept restricted to require long cleaning time. In view of the above, metal sodium is discharged from the equipment while being replaced with nitrogen gas and, thereafter, steam-containing helium gas is charged into the equipment to eliminate residual sodium. That is, helium having preferable heat conductivity (about 6-9 times greater than that of nitrogen and argon) is used as a medium capable of easy removing of reaction heat and preventing local temperature rise is used. Further, since helium has small molecular weight, it can rapidly prevail also to the upper portion of the equipment without stagnating in the lower portion thereof and can be eliminated in a short period of time. (Horiuchi, T. )