Radiolytic hydrogen production in heterogenous systems with plant relevance: Generic computational and experimental models.

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Various model systems, both computational and experimental, are used to under-pin hydrogen-related safety cases on plant. One of the major challenges for both decommissioning and plutonium stewardship concerns the radiolytic generation of hydrogen in heterogenous systems. For decommissioning this relates to the radio-lytic production of hydrogen in sludges, e.g. in magnox ponds, and in ion exchange resins. For plutonium stewardship the key issue is the build-up of hydrogen, believed to be due to the thin layers of water undergoing alpha radiolysis creating hydrogen which can pressurise the storage cans.We will unify experimental and simulation approaches providing near-real time comparison between them. A framework for sequential radiolytic hydrogen generation experiments and comparator simulations will be developed for sludges, colloids and wet/dry powders. In experiment, parameters to be varied under computer control include liquid composition (inc pH), head/dissolved gas environment and temperature. As well as al-lowing us to simulate expected headspace/dissolved gas compositions and age samples, we will be able to program the system to investigate the radiolytic generation and recombination of hydrogen across a range of situations relevant to plant safety activity ranging from 'pure' parameter determination experiments (e.g. G-values) to experiments able to probe the complex interplay of radiolytic production and removal of hydrogen alongside changes in the relevant interfacial chemistry.A parallel computational framework will be extended to make comparator simulations of the expected behaviour. It will be able to simulate the sequential experiments and then facilitate meaningful extrapolation to plant-scale pond-storage and plutonium stewardship problems.Drawing together our simulation and modelling research streams, in summary the student in this project will Perform a series of exemplar experiments and comparator simulations, studying effects of hydrogen production on: i) change of pH, dissolved gas and radiation/chemical aging on colloids and sludges such as brucite and ion exchange resins and ii) ii) water layer thickness, hydrogen/oxygen headspace gas composition, chlorine contamination and radiation/chemical aging on PuO2 simulants.An additional benefit of this dual strand approach is that it brings expertise of Dr Marcus Webb, a leading expert in the numerical methodology we are proposing, and which could be key to many simulation problems the industry faces.Due to its relevance to the nuclear industry this project relates to the EPSRC priority area of Energy/Decarbonisation