MULTI-SPECIES MULTI-PHYSICS MODELING AND VALIDATION OF HYDRODYNAMIC ELECTROCHEMICAL SYSTEM FOR USED NUCLEAR FUEL

Department of Nuclear EngineeringAccurate predictions of processes in hydrodynamic electrochemical systems require an understanding of both the surface electrochemical reactions and the bulk mass transport. Complete coupling of electrochemistry and fluid mechanics is computationally very rich for multidimensional modeling since it involves multiple components across multi-phases at the same time. Therefore, this study develops a computational model that combines a 3D model for calculating single-species mass transport and a 2D model for calculating multi-species electrochemical reactions. The computational model is validated against lab-scale experimental data using a rotating cylinder solid metal cathode and liquid metal anode in the Argonne National Laboratory. The 3D model assumes that U, the representative component in the system, dominates the hydrodynamic behavior, and thus calculates mass transport caused by the rotating solid cylinder electrode. The 2D model still reflects the diffusion of U, Pu, and Nd within a diffusion boundary layer and the bulk concentration changes of these components. The 3D model provides a diffusion layer thickness reflecting convective mass transfer effects to the 2D model. The results of the proposed model show good agreement with the reference experiment, and the model can be considered an important tool for investigating the multidimensional distributions of hydrodynamic and electrochemical variables.clos

Laser-Induced Breakdown Spectroscopy (LIBS) in a Novel Molten Salt Aerosol System

In the pyrochemical separation of used nuclear fuel (UNF), fission product, rare earth, and actinide chlorides accumulate in the molten salt electrolyte over time. Measuring this salt composition in near real-time is advantageous for operational efficiency, material accountability, and nuclear safeguards. Laser-induced breakdown spectroscopy (LIBS) has been proposed and demonstrated as a potential analytical approach for molten LiCl–KCl salts. However, all the studies conducted to date have used a static surface approach which can lead to issues with splashing, low repeatability, and poor sample homogeneity. In this initial study, a novel molten salt aerosol approach has been developed and explored to measure the composition of the salt via LIBS. The functionality of the system has been demonstrated as well as a basic optimization of the laser energy and nebulizer gas pressure used. Initial results have shown that this molten salt aerosol–LIBS system has a great potential as an analytical technique for measuring the molten salt electrolyte used in this UNF reprocessing technology

U.S.-South Korea relations

This report contains two main parts: a section describing recent events and a longer background section on key elements of the U.S.-South Korea relationship. The end of the report provides a list of CRS products on South Korea and North Korea

Nuclear power can be the answer

This paper reviews the development of fast molten salt nuclear reactors (MSRs) to close the nuclear fuel cycle by processing future and existing nuclear waste so that it can be returned safely to the environment. It follows two earlier papers outlining the overall use of a range of MSR types and an outline of future proposed marketing of a universal modular thermal MSR design for general purposes. It is suggested that the future MSR industry will probably evolve into three major competitive global corporations. The first one, serving the Far East, seems likely to become entirely MSR based, whereas the other two serving Europe/Western Russia and the Americas may use the alternative lead-cooled fast reactor for waste disposal, which is the closest competitor to the MSR system. Although construction of full-scale fast (MSR) reactors for closing the fuel cycle may not eventuate until some years into the future, it is concluded that this need not delay the introduction of the general purpose thermal MSR reactor envisaged earlier. This new nuclear technology is considered essential to maintain base-load electricity in a world where agricultural needs are expected to take precedence over space requirements for wind and solar farms. Using Thorium, in addition to Uranium, nuclear fuel is sufficient for the next 1000 years. Thus this energy resource can be considered pseudo-sustainable and give us the time to restore our world to a state of balance and true sustainability. Attention is also drawn to the present dangers of continuing to increase the storage of nuclear waste and the refurbishing of old-design nuclear plant, which are already 40 years old

Structure analysis of vitusite glass–ceramic waste forms using extended X-ray absorption fine structures

Vitusite glass–ceramic waste forms were developed and the local environments of the Nd3+ ions in the waste forms were analyzed using extended X-ray absorption fine structure (EXAFS) spectroscopy. A second shell was observed in the Fourier transform (FT) of the EXAFS Nd LIII-edge spectra with the formation of vitusite crystals in the glass matrix. This second shell was attributed to the presence of the Nd–P and Nd–Na ion pairs constituting the vitusite crystal. The preferred incorporation of Nd3+, P5+, and Na+ inside the crystalline phases surrounded by the glass matrix increased the chemical durability of the glass–ceramics