Radiation-resistant metal-organic framework enables efficient separation of krypton fission gas from spent nuclear fuel

Abstract

Capture and storage of volatile radionuclides that result from processing of used nuclear fuel is a major challenge. Solid adsorbents, in particular ultra-microporous metal-organic frameworks, could be effective in capturing these volatile radionuclides, including 85 Kr. However, metal-organic frameworks are found to have higher affinity for xenon than for krypton, and have comparable affinity for Kr and N 2. Also, the adsorbent needs to have high radiation stability. To address these challenges, here we evaluate a series of ultra-microporous metalorganic frameworks, SIFSIX-3-M (M = Zn, Cu, Ni, Co, or Fe) for their capability in 85 Kr separation and storage using a two-bed breakthrough method. These materials were found to have higher Kr/N 2 selectivity than current benchmark materials, which leads to a notable decrease in the nuclear waste volume. The materials were systematically studied for gamma and beta irradiation stability, and SIFSIX-3-Cu is found to be the most radiation resistant.

High‐Silica CHA Zeolite Membrane with Ultra‐High Selectivity and Irradiation Stability for Krypton/Xenon Separation

“…CHA zeolite without any impurity phase was identified from PXRD patterns (Figure 5 c). In contrast, phase changes were observed for MOF SIFSIX‐3 at 1 kGy [12a] and nickel formate was identified for MOF NiDOBDC at 67.2 kGy [42] . For current benchmark SAPO‐34 zeolite membranes, the separation performance dropped by 36.6 % over 60 days storage and irradiation under atmosphere conditions [20] .…”

“…The reported polycrystalline membranes for Kr/Xe separation, such as SAPO‐34, [16a–d] are extremely sensitive to moisture because channel blockage [17] and framework collapse [18] occurred through water uptake from off‐gas streams [19] . Sufficient resistance to γ‐radiation is another essential criterion for practical application using radioactive 85 Kr, [12a] but the radiation stability of polycrystalline membranes is hardly reported [20]…”

Efficient Xe selective separation from Xe/Kr/N2 mixtures over a microporous CALF-20 framework

“…Alternatively, extensive research has been done to adopt physisorption with suitable absorbents to capture and separate Xe and Kr at or near room temperature for the advantages of low cost, high efficiency, and reliability. 1,7 Currently, activated carbon, 8-10 zeolites, [11][12][13][14] and metalorganic frameworks (MOFs) 15,16 have drawn great attention for the high-efficient separation of Xe and Kr by adsorption. However, there is always a major challenge to efficiently capture the trace noble gases from the gas mixture because of their chemical inertness and small size difference with nitrogen (kinetic diameter: Kr, 3.65 Å; N 2 , 3.84 Å; Xe, 4.04 Å).…”

A microporous Ce-based MOF with the octahedron cage for highly selective adsorption towards xenon over krypton

“…SIFSIX-3-Cu showed a dynamic selectivity of 4.81 with Xe/Kr and 24.38 with Kr/N 2 in dry air, which could endure 50 kGy b and g irradiation. 42,43 Yan et al reported a series of Zr-Fum MOF and UiO-66(Zr), the Zr-Fum-Me possessed a Henry's selectivity of 14.8 with a dose of 8 kGy gray irradiation resistant, UiO-66(Zr) owns a similar structure to that of Zr-Fum with a Xe/Kr selectivity of 7.7 and 2 kGy g irradiation resistance. 44,45 Cerium is a rare-earth metal in the lanthanide class possessing advantages of affordability and accessibility in nature.…”