Experimental fast reactor JOYO operational experience; The operational experiences of JOYO secondary sodium purification system

not registered; Terano, Toshihiro; not registered; Onuki, Osamu; not registered; Okubo, Toshiyuki; not registered

This paper describes operational experiences of JOYO Secondary Sodium Purification System which were obtained from April 1990 to March 1995. And, the operational problem of Secondary Sodium Purification System with MK-III core conversion were mentioned in this report. The experience results were as follows. (1)The number of cases of the secondary purification system trouble was 12. Those troubles, however, did not affect to the operation of the plant. (2)As the result of investigation about possibility of using secondary cold trap after MK-III core conversion, amount of trapped impurity was estimated 9.4kg as of January, 1994. In addition, 25.2kg was the estimated amount of trapped impurity at sodium initial purification after MK-III core conversion. It was subtantial excess of original design(18kg). (3)The change of heat transfer characteristics of secondary cold trap economizer occurred about two years after the modification of cold trap control tempereture. It seemed to be led by condition change of sticking impurity to heat transfer tubes which was followed by the modification of set up temperature. When set up temperature had been kept low, heat transfer characteristics was better. (4)A large quantity of sodium vapor was identified on the secondary argon gas system pressure control header. The influence of engulfing of argon gas at over flow line of Secondary Sodium Purification System is concerned.