Christopher TigheExperimental Officer for Accelerator Mass Spectrometry
Testing new methods of non-destructive radioactive assay of uncharacterised soil samples for use at the Dounreay decommissioning facility to increase throughput of current methods employed at the site.Currently, Dounreay employs alpha counting methods to characterise soil samples. This is a low throughput, high time and personnel intensive procedure that takes up to three weeks for the processing of one sample. This area is a clear bottleneck in the organisation's soil analysis, highlighting the need for the adoption of new methods.Chief amongst the new methods we are researching is the measurement of fast neutrons emitted from samples utilising liquid scintillation detectors and mixed-field analysers with the advent of improvements to the speed of digital measurement techniques. This involves the counting of the net number of neutrons emitted from a sample with a high efficiency detector array. The neutron numbers can then be compared to literature values of expected amounts of fuel cycle isotopes and their respective neutron emissions over the detection time.Gamma detection of the samples can also be employed as a method of corroborating the number of neutrons measured against the expected gamma output of the sample and the practical gamma output of the sample to derive any potential discrepancies between the theoretical and practical values.