Radionuclides in target station coolant in the China Spallation Neutron Source.

The China Spallation Neutron Source (CSNS) is the first pulsed neutron source in China for multidisciplinary research. After operation with 80 kW proton beam for 4 months, 3 circuits of target station coolant, light water 1/2/3 were sampled, and radionuclides in coolants were measured. The results showed that, activity concentration of H-3 in coolant can be up to the magnitude of 1.00E+06 Bq/L, and the H-3 amount in light water 1 was the highest and the amount in light water 3 was the lowest, agreeing with the radiation field exposed by coolants. For Be-7, due to the complicated filtering and trapping process, amount of Be-7 in coolant differed from a minimum of 7.15E+01 Bq/L to a maximum of 4.58E+03 Bq/L. Comparison of the results with former measurements and simulated results were conducted. Permitted volumes for coolant discharge were presented. And the work time in the equipment room of cooling system after the beam is shut off is safe. Results in this research could provide reference data and measurement methods for similar accelerator devices.