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Beta particle energy spectra shift due to self-attenuation effects in environmental sources
Thomas Theakston Alton,Stephen David Monk,David Cheneler 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.7
In order to predict and control the environmental and health impacts of ionizing radiation in environmentalsources such as groundwater, it is necessary to identify the radionuclides present. Beta-emittingradionuclides are frequently identified by measuring their characteristic energy spectra. The presentwork shows that self-attenuation effects from volume sources result in a geometry-dependent shift inthe characteristic spectra, which needs to be taken into account in order to correctly identify the radionuclidespresent. These effects are shown to be compounded due to the subsequent shift in thephoton spectra produced by the detector, in this case an inorganic solid scintillator (CaF2:Eu) monitoredusing a silicon photomultiplier. Using tritiated water as an environmentally relevant, and notoriouslydifficult to monitor case study, analytical predictions for the shift in the energy spectra as a function ofdepth of source have been derived. These predictions have been validated using Geant4 simulations andexperimental results measured using bespoke instrumentation.
Radiation testing of low cost, commercial off the shelf microcontroller board
Fried, Tomas,Di Buono, Antonio,Cheneler, David,Cockbain, Neil,Dodds, Jonathan M.,Green, Peter R.,Lennox, Barry,Taylor, C. James,Monk, Stephen D. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.10
The impact of gamma radiation on a commercial off the shelf microcontroller board has been investigated. Three different tests have been performed to ascertain the radiation tolerance of the device from a nuclear decommissioning deployment perspective. The first test analyses the effect of radiation on the output voltage of the on-board voltage regulator during irradiation. The second test evaluated the effect of gamma radiation on the voltage characteristics of analogue and digital inputs and outputs. The final test analyses the functionality of the microcontroller when using an external, shielded voltage regulator instead of the on-board voltage regulator. The results suggest that a series of latch-ups occurs in the microcontroller during irradiation, causing increased current drain which can damage the voltage regulator if it does not have short-circuit protection. The analogue to digital conversion functionality appears to be more sensitive to gamma radiation than digital and analogue output functionality. Using an external, shielded voltage regulator can prove beneficial when used for certain applications. The collected data suggests that detaching the voltage regulator can extend the lifespan of the platform up to approximately 350 Gy.