[en] We report on the remarkable property of silver exchanged zeolites to efficiently adsorb radon at room temperature. We investigated three commercially available zeolite materials and compared their adsorption performance to commonly available activated carbons by measuring ²²²Rn breakthrough curves under different experimental conditions. Depending on the type of carrier gas and gas velocity, dynamic adsorption factors k were found to be at least two orders of magnitude higher for zeolite materials as compared to activated carbons. Moisture control was found to be crucial for effective ²²²Rn adsorption since water has shown to exhibit a strong competitive effect. This contribution will present experimental results obtained from systematic investigations involving the practical usage of these materials. It is shown that more compact and economic room-temperature ²²²Rn adsorption systems can be designed using silver exchanged zeolites considerably reducing the impact of ²²²Rn originating from ²²⁶Ra emanations in environmental, scientific and industrial applications

[en] Thorium-229 is a valuable, but scarce, radionuclide for nuclear clock applications or targeted alpha therapy. While it is mostly produced by the decay of "2"3"3U, "2"2"9Th can also be produced by neutron irradiation of "2"2"6Ra. At SCK• CEN, capsules containing mainly "2"2"8Th (by-product of "2"2"6Ra irradiation) were characterized to quantify the present amounts of "2"2"9Th, "2"2"8Th, "2"2"7Ac, "2"2"6Ra with high resolution gamma spectroscopy, after a decay period of 40 years in which "2"2"8Th has decayed. High purity "2"2"9Th was quantified, and after recovery using radiochemical separation processes, it can be used to support ongoing research. - Highlights: • Presence of "2"2"9Th of high radioisotopic purity in historical capsules was proven. • Amounts of "2"2"9Th, "2"2"8Th, "2"2"7Ac and "2"2"6Ra were quantified using in-situ gamma-ray spectroscopy. • Thorium-229 found in the historical capsules can support ongoing research after a recovery campaign.