Behavior of particulate impurities in sodium system; Tests by mesh-type and magnetic-type filters

Sasaki, Shuichi; not registered; Himeno, Yoshiaki; not registered; Iguchi, Tatsuro*

In an sodium test facility, particulate impurities are accumulated with time progresses when it has been operated for long period of times at elevated temperatures. Similar event may also be happen in coolant systems of LMFBR. In particular, deposition of radioactive corrosion products in sodium components and in pipings of a primary coolant system of the reactor may causes in high radiation background around them. But, the fact is that behavior of particulate corrosion products in sodium system is not well understood. No information is available, except few experimental findings. To meet the requirement, a series of tests have been conducted placing their emphasis on determinations of particle sizes, elements compositions, and concentration of particulate in flowing sodium system. Mesh-type and magnetic-type filters were used for these purposes. Results here obtained are summerized as follows. (1)Particulate concentrations of the present sodium loop ranged from 15 ppb depending strongly upon flow velocity in main sodium curculation piping. This suggests that concentration is being controlled by settling of particles. (2)Particle sizes determined ranged from sub-micron to 50 m, while their mean radius was 2-3 m. (3)Main compositional elements of particulates were Fe (18-48%), Cr (4.4-18%), Mn (4-9%), Ni(2-3%), and Si(3-4%). (4)Both the present mesh-type and magnetic-type filters worked effectively for collecting and trapping particulates in the loop sodium.