Facing the global shortage of medical facemask in the current COVID-19 crisis, the RUM (Re-Used Masks) French consortium explores the feasibility of recycling masks after a first use. Radiation processing was the first virucide technique of decontamination that was investigated in this consortium. Tests were carried out using the 60 Co gamma irradiator of ARC-Nucléart and with Ionisos industrial facilities, including 60 Co irradiation and e-beam. 20 kGy is the reference maximum dose that was mainly used in this study, as a dose able to ensure a 10 kGy minimum dose in a mass processing leading to a decontamination (-5 log reduction) as based on surrogate of SARS-COV-2. Conservation of masks performance and behavior of the materials after treatment were studied in the consortium and by commercial laboratories for standard testing. Data available at date of 12th May 2020 are compiled and discussed in this report. Unfortunately, our results indicate a clear loss of submicronic filtration efficiency because of electric discharge of the electrostatic filter (electret) of FFP2 masks. This is believed to be due to high density of ionisation. This is confirmed whatever the operative condition tested in this study. In the other hand, loss of efficiency is low in the micronic range. The treatment of surgical masks by ionizing radiation is still interesting but gamma irradiation in air must be avoided to prevent beginning of oxidation of PP that could lead to important delayed post-effect degradation. Care must also be taken about degradation products after consumption of antioxidant, in few amounts at doses between 10 and 20 kGy. Generally speaking, the choice of a method in the frame of reuse of surgical masks during crisis must pass through a complete risk analysis. In this case, it must include the evaluation of the right dose and operative condition with regards of the benefit in terms of virucide reliability for instance and the potential drawback such as loss of efficiency or amount of unwanted compounds.