[en] Electrochemical processes appear to be attractive for treating low level nuclear wastes. The development of a simple divided electrochemical-cell model operating in a batch mode, used for the reduction of nitrates and nitrites from nuclear wastes, is presented. This model, based on a boundary-layer approach, is simple and yet encompasses the key features of a previously developed distributed-parameter model that includes diffusion, migration, and convection as the flux components. Because it dramatically reduces computation time, this boundary-layer model is well suited for use in a complex interactive flowsheet model and for optimization studies. The boundary-layer model is sued to predict partial current densities, reservoir concentrations, and off-gas compositions as a function of time. Good agreement between simulated and experimental data (i.e., nitrate and nitrite concentrations and off-gas compositions) is observed over the course of a batch run. In addition, a comparison with a rigorous distributed-parameter model is made to illustrate the accuracy and robustness of this model. The results of selected case studies are shown, and a preliminary batch optimization is carried out to show how the model can be used to maximize the destruction of nitrates and nitrites

[en] This paper describes a proof of principle experiment to produce ¹³N using an inertial electrostatic confinement (IEC) fusion device. This radioisotope is often used in positron emission tomography scans to image the heart. The 10-minute half-life of ¹³N limits its use to those areas and clinics that possess an accelerator. A portable IEC device could be brought to remote locations, however, and produce short-lived PET isotopes on-site. Using the 14.7 MeV protons produced from the D-³He fuel cycle, University of Wisconsin IEC device was used to produce approximately 4 - 8 Bq of ¹³N during two separate experiments

[en] A model of a divided parallel plate electrochemical cell operated in a batch mode for the destruction of NO₃^-/NO₂^- in alkaline waste streams is presented. The model uses boundary layer approximations at each electrode and at the separator to minimize computation time. Five competing electrochemical reactions are included at the cathode. The model uses either an explicit Runge-Kutta routine with empirically determined current efficiencies or an implicit stepping routine for each electrode if the current efficiencies are to be predicted. Tim dependent changes of the concentration, temperature, and cell voltage are predicted for constant current operation. Model predictions are compared with experimental data

[en] The objective of this report is to describe the modeling and optimization procedure for the electrochemical removal of nitrates and nitrites from low level radioactive wastes. The simulation is carried out in SPEEDUP trademark, which is a state of the art flowsheet modeling package. The flowsheet model will provide a better understanding of the process and aid in the scale-up of the system. For example, the flowsheet model has shown that the electrochemical cell must be operated in batch mode to achieve 95 percent destruction. The flowsheet model is detailed in this report along with a systematic description of the batch optimization of the electrochemical cell. Results from two batch runs and one optimization run are also presented

[en] Cross sections for ^223,225Ra, ²²⁵Ac and ²²⁷Th production by the proton bombardment of natural thorium targets were measured at proton energies below 200 MeV. Our measurements are in good agreement with previously published data and offer a complete excitation function for ^223,225Ra in the energy range above 90 MeV. Comparison of theoretical predictions with the experimental data shows reasonable-to-good agreement. Results indicate that accelerator-based production of ²²⁵Ac and ²²³Ra below 200 MeV is a viable production method. - Highlights: ► Natural thorium targets were irradiated with protons up to a nominal 200 MeV. ► ²²⁵Ac, ^223,225Ra, and ²²⁷Th production cross sections were measured. ► Multi-curie quantities of ²²⁵Ac and ²²³Ra can likely be produced at Los Alamos and Brookhaven. ► Accelerator-based production of ²²⁵Ac and ²²³Ra is a viable production method

[en] Cross sections for the formation of ^225,227Ac, ^223,225Ra, and ²²⁷Th via the proton bombardment of natural thorium targets were measured at a nominal proton energy of 800 MeV. No earlier experimental cross section data for the production of ^223,225Ra, ²²⁷Ac and ²²⁷Th by this method were found in the literature. A comparison of theoretical predictions with the experimental data shows agreement within a factor of two. Results indicate that accelerator-based production of ²²⁵Ac and ²²³Ra is a viable production method. - Highlights: ► Natural thorium targets were irradiated with protons at a nominal 800 MeV. ► ^225,227Ac, ^223,225Ra, and ²²⁷Th production cross sections were measured. ► First measurement of ²²⁷Ac, ^223,225Ra, and ²²⁷Th cross sections at 800 MeV. ► Accelerator-based production of ²²⁵Ac and ²²³Ra is a viable production method.