Development of a technique to study behavior of iron oxides in PWR secondary water

To develop an experimental technique to study behavior of iron oxides in PWR secondary water, investigation of suspended solids in PWR secondary system water was carried out and an experimental facility which can simulate PWR secondary conditions was fabricated. Obtained are as follows. (1) In PWR secondary water iron oxyhydroxide which is generated at low temperature (condensate) changed to magnetite with temperature and magnetite content in suspended solids increased with temperature. It means that reducing condition is getting stronger with temperature. Correlation between hydrazine concentration and magnetite content in the water was obtained. (2) In an experimental facility which simulates operating plant conditions, iron oxyhydroxide, which was injected in low temperature feedwater, reduced to magnetite with temperature. And magnetite content in suspended solids increased with hydrazine concentration in the water. Increasing tendency of magnetite content in this experiment was similar to that in operating plant. (3) As mentioned above, this experimental facility has ability to reproduce behavior of iron oxides in PWR secondary water. It was verified that this facility is effective in experiment which reproduce PWR secondary environment. Using this experimental facility, it is planned to proceed further investigation on the behavior of iron compounds in PWR secondary system. (J.P.N.)