Activity monitoring and transport studies around the primary heat transport system of RAPS-I

The build-up of activity on the out-of-core locations of the primary heat transport system of RAPS-1 has been studied. The following pattern of activity was found: (i) 60CO and 58Co were the main deposited activities, (ii) buildup of activity was more on colder sections than on hotter sections of the pipe and (iii) relative increase of 58Co and 60Co were more on north side as compared to that on corresponding locations on the south side (during 1973-74). Subsequent findings revealed that: (i) the contamination levels continue to be more on boiler outlet pipe (colder sections) than that on boiler inlet pipe (hotter sections), (ii) initially the relative increase of 58Co and 60Co and ratio 58Co/60Co were found to be more on one bank of boilers (north side) as compared to the corresponding locations on the other bank of boilers (south side) indicating a small differential in the total coolant flow through the two banks and (iii) a discontinuity was observed around 170 EF PD of operation. It is concluded that the activity of the coolant and of the surfaces of the primary heat transport circuit due to corrosion products seems to be a complex function of various parameters of the reactor system such as temperature, pressure, pH, coolant flow rate, etc. (K.B.)