Measurement and evaluation of the radioactive corrosion product behavior in the primary sodium loops of "JOYO" (III)

Chatani, Keiji; not registered ; Ito, Chikara   ; Setyadi*; not registered; not registered

Deposition density and gamma dose rate of the radioactive corrosion product(CP) have been measured along the primary sodium loop in Experimental Fast Reactor "JOYO" during every annual inspection in order to make clear the CP behavior and to verify the CP behavior analysis code "PSYCHE". As a result of the previous seven CP measurements, it is made clear that major CP nuclides deposited in the primary sodium loops are Mn on the cold leg (CL) piping (from the outlet of the Intermediate Heat Exchanger (IHX) to the inlet of the reactor vessel (R/V)) and Co on the hot leg (HL) piping (from the outlet of the R/V to the inlet of the IHX), and so on. In this study the CP behavior has been evaluated by using the measurement results during the 10th annual inspection. The results of this study are summarized as follows: (1)The distribution of the measured CP deposition density and gamma dose rate show the same tendency observed previously and no unusual phenomenon is observed. (2)The buildup of Mn and Co is seemed to reach saturation because the average CP deposition density and the averaged dose rate is the same value as measured in the 9th annual inspection. (a)Deposition density of Mn is 30kBq/cm for HL piping, 60 kBq/cm at CL(1) piping (from the outlet of the IHX to the inlet of the pump) and 130 kBq/cm at CL(2) piping (from the outlet of the pump to the inlet of the R/V). Deposition density of Co is 9 kBq/cm at HL piping, 3kBq/cm at CL(1) piping and 9 kBq/cm at CL(2) piping. (b)Dose rate is 0.5mSV/h at HL piping, 0.6mSV/h at CL(1) piping and 1 mSV/h at CL(2) piping. (3)As a comparison between "PSYCHE" calculation(C) and measurement(E), C/E ratio is 0.9 to 1.5 for CP deposition density, and 1.6 for dose rate. The agreement between calculation and measurement is fairly good.