Screening of experiment set-ups in HADES for evaluating the possibilities of a new gas in situ experiment

With the purpose of performing a large scale in situ gas diffusion and breakthrough experiment, a detailed screening of experimental set-ups in HADES has been performed. After the application of a vast set of selection and exclusion criteria, only MEGAS is considered to be suitable to perform a large scale diffusion experiment with dissolved gases. In a next step, all details on the MEGAS set-up, including position, history, pressure data etc. have been collected. Based on this information, scoping calculations have been performed. Results indicate that the evolution of the gas concentration in time (passing a detection limit of 100 ppm) can be measured from 1 year on (for two filters), and from 3 years on for a third filter. Also the injection method has been investigated. Given the importance of obtaining good exchange of dissolved gas between the filter chambers and the gas/water vessels, we propose to use the system of dissolved gases in water, where water in pumped around continously. None of the available set-ups is currently suitable for both a diffusion and a breakthrough experiment. Some set-ups could be used for gas injection, but additional monitoring boreholes should be drilled. For the next stage, we propose to design the set-up in more detail, a process which should occur in close collaboration with the ESV Euridice.