In this study, we have investigated the iodine retention behavior of silver zeolite sorbents under a variety of conditions. First, a preliminary study was achieved in liquid phase in order to determine: (i) the main kinetic and thermodynamic characteristics pertaining to the adsorption behavior; (ii) the influence of some zeolitic parameters (nature of the framework, silver content,

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A series of experimental tests were performed to measure the efficiency of volatile iodine trapping on sand bed filters and metallic filters. These filtering media are used in French nuclear power plants to mitigate releases in case of severe accident. The results show that molecular iodine is more easily trapped than methyl iodide due to its high chemical affinity with stainless steel or with silver and cesium cations included in the filter medium. For methyl iodide, the trapping efficiency is low.

This paper deals with near past, ongoing, and planned R&D works on fission products (FPs) behavior in reactor cooling system (RCS), containment building and in filtered containment venting systems (FCVS) for severe accident (SA) conditions. All the researches are collaborative works; the overall objective is to develop confident models to be implemented in simulation software. After being initiated in 2004, researches on iodine transport through the RCS are still ongoing and for containment, the last advances are linked to the source term (ST) evaluation and mitigation (STEM) OECD/NEA project. The objective is to improve the evaluation of ST for a SA on a nuclear power plant and to reduce uncertainties on specific phenomena dealing with the chemistry of two major FPs: iodine and ruthenium. For ruthenium attention has been paid to study the amount and nature (gas/aerosol partition) of ruthenium species along the RCS. A follow-up, called STEM2, has started to reduce some remaining issues and be closer to reactor conditions. For FCVS works, the efficiencies for trapping iodine covering scrubbers and dry filters are examined to get a clear view of their abilities in SA conditions. Another part is focused on specific porous materials able to trap volatile iodine. Influence of zeolite materials parameters (nature of the counter-ions, structure, Si/Al ratio…) are tested as well as new kind of porous materials constituted by Metal organic Frameworks will also be looked at.

In the frame of severe accident topic for pressurized water reactor, the physical-chemistry of Ru fission products were experimentally studied to better understand their behavior inside the reactor coolant system in air or air/steam atmospheres. The tests consisted in vaporizing RuO at 1200°C and the ruthenium oxides are transported through a controlled thermal gradient tube made of quartz or preoxidized stainless steel. Results show that the major part up to 95% is deposited along the tube, the remaining part being transported almost under gaseous form attributed to RuO. Impact of carrier gas, temperature profile and nature of the tube are discussed.