Process intensification applied to spent nuclear fuel reprocessing: An alternative flowsheet using small channels

Abstract

Commercial plants for spent nuclear fuel reprocessing rely on the Plutonium Uranium Extraction (PUREX) process, based on traditional liquid-liquid extraction technologies. In this paper, an alternative flowsheet for spent nuclear fuel reprocessing is proposed, based on small-scale extractors to overcome some of the issues related to the conventional technologies, such as solvent degradation, size and nuclear criticality control. The main goal of the process is to preclude the risk of nuclear proliferation, hence a mixed uranium/plutonium oxide is produced instead of pure plutonium.A superstructure optimisation based framework has been used to identify a process with several benefits over the conventional process. Novel flow configurations and organic solvent composition have been investigated. A large number of components and chemical reactions are included in the framework. The resulting model is a mixed integer nonlinear optimisation problem, implemented in the General Algebraic Modeling System (GAMS).The most promising flowsheet identified is more cost effective than the conventional one. Furthermore, advantages in terms of safety and separation efficiency have been achieved. It was found that increasing the inner diameter of the small channels up to 2.5 mm, as well as increasing the tributyl phosphate fraction in the organic solvent, are advantageous.

Nuclear Waste Management

“…To address this problem, various separation processes, such as COEX (combined U and Pu extraction), GANEX (grouped actinide extraction), and UREX (uranium extraction) are being developed. [26][27][28][29][30][31][32][33][34][35] Alongside the separation process, partitioning and transmutation technology is one of the potential future solutions for nuclear waste management. This technology is based on the quantitative recycling of long-lived and highly radiotoxic nuclides through pyrometallurgical processing to create new fuel for use in advanced fast-neutron reactors.…”

Intensified liquid-liquid extraction of biomolecules using ionic liquids in small channels

“…To select the optimum residence time, the extraction needs to be considered within the whole process flowsheet (see for example [67], [68]). The results reported here on mass transfer coefficients can be used to study and optimize such process flowsheets.…”

Design optimization of microfluidic-based solvent extraction systems for radionuclides detection

“…The process implements a separation procedure combining both extraction and scrubbing steps. This suggested process does not consider recycling of the solvent, a feature of large scale reprocessing plants which deal with much larger volumes [35] but which is not necessary for a micro-analytic detection system. As a result, a stripping step to recover the solvent is not considered.…”

“…Instead, a simpler model, which incorporates overall mass transfer coefficients derived from dimensional analysis and experiments data [11,14,15,22], has been implemented. This approach has been used previously for large scale separation process design for reprocessing [16,35].…”

“…Both reprocessing and detection therefore share aspects of design goals. However, in the case of reprocessing, the feed to the process is usually well characterised [26,35]. For a detector, although certain information about the feed would have to be known to motivate its analysis, such a feed is usually not well characterised.…”