Radioactive decay assessments
By their very nature, all radioactive atoms undergo a process of radioactive decay. The quantity of radioactivity present at any one time varies depending on the radioactive half-life of the individual radionuclide concerned. In some cases the radionuclides decay to a stable form and in other cases they decay to other radioactive species which are then subject to further decay processes.
Often people just want a quick assessment of how much radioactivity is present at a specified date but the only information they have is the quantity of radioactivity present at some date in the past. For this type of simple assessment then simple decay calculations can be performed.
However for more complex radioactive decay assessments it is important to take into account the progeny of the decay process and their subsequent radioactive decays. These decay assessments become increasingly more complex as the number of radionuclides present at the start of the decay period, or the number of daughter progeny, increases. A simple situation is illustrated here with the ingrowth of Ba-137m, and its subsequent decay, as a result of the decay of Cs-137.
For some radionuclide mixes, the dose rates from the mixture can increase as the material decays due to the ingrowth of radionuclides that emit gamma or X-ray radiations rather than being alpha emitters. A good knowledge of how radionuclide mixtures evolve is essential in long term planning of radiological protection arrangements in facilities.
RP Alba Ltd personnel have performed a range of specialised radioactive decay assessments for clients for highly complex radionuclide mixes. These assessments have been performed for the characterisation of existing materials and the long term management (including long term disposal) of high activity wastes.
RP Alba Ltd uses RadDecay software and other models to fully account for all potential radionuclides. The decay chains can be calculated for as many as 20 generations of progeny and identical daughter nuclides generated along different branches of the decay chains are alternately combined.
If you have complex radionuclide mixtures and wish to know how it evolves over time into different radionuclide mixtures then we can perform these assessments for you. As a follow on, upon the determination of the radionuclide mixture at the date of interest we can then provide estimates of the likely radiation dose rates emanating from these radionuclide mixtures as part of an assessment of estimate doses to potential exposed groups (PEGs).
If you need help with the characterisation of your radioactive materials/waste or require assistance with the assessment of your radionuclide mixtures as they evolve over time then please contact us to discuss how we can help you.