Distribution of ¹⁶N and ¹⁹O in the Reactor Pool Water of the THOR Facility

Radioactive ¹⁶N and ¹⁹O in the Tsing Hua Open-Pool Reactor, produced from ¹⁶O(n,p)¹⁶N and ¹⁸O(n,γ)¹⁹O reactions, respectively, have been measured using a rapid sampling device and gamma-ray spectroscopic systems. The radioactivity of the 7-s half-life ¹⁶N and 27-s half-life ¹⁹O in the pool water are monitored in the power range from 1 W to 1 MW. The three-dimensional concentration of these radionuclides in the water coolant is also contour mapped down to the detection limit of 10 Bq/ℓ. The spatial distribution of the short-lived radionuclides in the reactor pool, resulting from both the neutron flux distribution and heat transfer characteristics external to the core, is discussed for reactor operation at various power levels.