Tritiated Water Measurements with a ²D(γ,n)¹H Detector

Tritiated process water is monitored by detecting the D₂O component via the ²D(γ,n)¹H reaction. A probe containing a 1- to 7-mCi ²⁴Na (15-h) gamma source and six ³He neutron detectors produces and monitors the ²D(γ, n)¹H reaction. A variety of probe configurations were examined for D₂O detection sensitivity. The corresponding detection limits range from 6 to 280 µl for D₂O droplets and 1 to 13 µl/cm for D₂O streams, when 10-min neutron counting with a 1-mCi gamma source is used. Results from two field applications illustrate the utility of the monitor.