How does chemistry contribute to circular economy in nuclear energy systems to make them more sustainable and ecological?

Abstract

While one should be aware that its zero CO2 emission is actually achievable only when electric power is generated, nuclear power is one of the most viable and proven “carbon-free”...

Securing Reversibility of UVO2+/UVIO22+ Redox Equilibrium in [emim]Tf2N‐Based Liquid Electrolytes towards Uranium Redox‐Flow Battery

“…This suggests that the negatively charged [U VI O 2 Cl 4 ] 2À is formed by the Cl À loading, and requires more negative potential to reduce it to [U V O 2 Cl 4 ] 3À in Eq. (1). In contrast, an anodic wave coupled with the cathodic one at À 1.1 V vs. Fc/Fc + is almost missing under this condition.…”

“…As described in our former Perspective article, [1] several hurdles are still present to apply DU to RFB. If the [U V O 2 Cl 4 ] 3À / [U VI O 2 Cl 4 ] 2À redox couple (E°' = À 1.125 V vs. Fc/Fc + ) studied here is combined with [U III Cl 6 ] 3À /[U IV Cl 6 ] 2À (E°' = À 1.559 V vs. Fc/Fc + ) we reported previously, [11] the expectable electromotive force (emf) in a single cell of this U-based RFB will be only 0.434 V. This is much smaller than that of the V-based RFB (1.26 V) already implemented.…”

“…In addition, extra concerns are also present in actual application of DU to RFB in terms of chemical and radiation safety as well as final disposition of related wastes. [1,25] All U isotopes naturally occurring are radioactive, so that utilization of DU has to follow the radiation protection principles.…”

“…However, we also have to seriously think various cumbersome issues arising from nuclear wastes. [1] While backend stream after nuclear power production such as spent nuclear fuels and high-level radioactive wastes is frequently focused, one has to be aware that depleted uranium (DU) is also afforded as another nuclear waste after enrichment of a fissile U isotope, 235 U, to prepare fresh nuclear fuels for the light water reactors. [2] Despite the cost and labor dedicated for mining and refining natural U as well as the following 235 U isotope enrichment, few applications of DU are available except for fertiles to breed Pu and some military uses such as penetrating projectiles.…”

“…[8] Despite significant efforts dedicated to molecular design of organic ligands, the above problems are not fully resolved even today. [1] In contrast, stabilization of U species at any valence states is not always difficult in molten salts and their eutectics, although a highly volatile species like UX 6 (X = F, Cl) may be formed and tends to escape from such a high temperature system. Therefore, we can learn something and get helpful hints from such pyrochemical processes.…”