The CEA is not a think tank. It is indeed a public research institute specializing in nuclear energy but with zero contribution from private individuals or investors, nor does it fit any other part of the definition of think tank or is included in any think tank ranking. The CEA's annual budget is € 5 billion, whereas the IFRI (Institut Français des Relations Internationales, definitely a think tank) is only € 7 million.
Furthermore, the CEA is leading the project for very good reasons and the help of companies manufacturing airport metal detectors makes perfect sense:
"3) Enhanced relocatable unit for non-intrusive detection of wide number of threats including explosives, illicit drugs, chemical warfare agents, nuclear and radioactive materials (NR) and special nuclear materials (SNM) such as enriched uranium and plutonium, 4) Trans-European RPM network for passive detection of illicit nuclear and radioactive (NR) materials combining detection facilities of different types and technologies" (simply quoting your sources)
Furthermore, the CEA is leading the project for very good reasons and the help of companies manufacturing airport metal detectors makes perfect sense: "3) Enhanced relocatable unit for non-intrusive detection of wide number of threats including explosives, illicit drugs, chemical warfare agents, nuclear and radioactive materials (NR) and special nuclear materials (SNM) such as enriched uranium and plutonium, 4) Trans-European RPM network for passive detection of illicit nuclear and radioactive (NR) materials combining detection facilities of different types and technologies" (simply quoting your sources)