The EU-PASSAM (Passive and Active Systems on Severe Accident source term Mitigation) project was launched in the frame of the 7^th framework programme of the European Commission. It aims at investigating potential phenomena that might enhance source term mitigation in case of a severe accident in a LWR. Both already existing systems (i.e., water scrubbing and sand bed filters plus metallic pre-filters) and innovative ones (i.e., high pressure sprays, electrostatic precipitators, acoustic agglomerators, advanced zeolites and combined wet-dry filtration systems), are being experimentally characterized and their performance under anticipated conditions explored.

After more than three years running, the experimental work is well advanced and interesting results are being produced in terms of phenomena understanding, long term behavior, and supplementary and alternative ways to mitigate even further source term if in the course of the accident containment is decided to be filtered vented. As an example, experimentation on pool scrubbing has shown that gas hydrodynamics, at least in some relevant scenarios, is significantly different from what is nowadays encapsulated in severe accident analysis codes, particularly at high velocities and, that in the long run, maintaining a high pH in the scrubber solution is absolutely necessary for preventing a delayed iodine release. As for organic iodine trapping, some of the systems tested, e.g. zeolites, showed substantial efficiencies. This paper sums up and illustrates these and other insightful results obtained so far.

In addition to experiments, simple models and/or correlations are being developed, so that their eventual implementation in severe accident analysis codes, should allow enhancing the capability of modelling Severe Accident Management measures and developing improved guidelines.

The present paper is just a foretaste of the open final PASSAM workshop that will be organized on February 28^th and March 1^st, 2017 in Paris (France). There, a detailed presentation of the outcomes of the project will be carried out.