In the operation of a nuclear power plant, it is very important to determine the time evolution of material composition and radionuclide inventory during the entire operation of the plant. In the experiments, the Monte Carlo N-Particle eXtended (MCNPX) code was found to be accurate in predicting the uranium fuel depletion, the plutonium production and the buildup of most of the fission products in a nuclear reactor. The goal in this chapter is to analyze the effect of different nuclear fuel grades on the total radioactivity of the reactor core by employing nuclear burnup calculations for the three different fuels: mixed oxide fuel (MOX), uranium oxide fuel (UOX) and commercially enriched uranium (CEU), utilizing simulations with MCNPX code. The calculated results indicate that there is a buildup of plutonium isotopes for UOX and CEU, whereas there is a decline in the plutonium radioisotopes for MOX fuel with burnup time. The study of reactor neutronic parameters showed UOX fuel performs better relative to MOX and CEU. Zircaloy, with low thermal neutron absorption cross-section and high thermal conductivity, produced better results for the effective multiplication factor Keff and hence proved to be a much more effective clad material.
Part of the book: Nuclear Material Performance
Part of the book: Osmotically Driven Membrane Processes
Forward osmosis (FO) and membrane distillation (MD) are two emerging membrane technologies, and both have advantages of low membrane fouling, ability to use for highly saline desalination, and feasibility to integrate with a low-grade heat source like solar collector. Because polyethylene glycol (PEG) is a flexible, water-soluble polymer, it is an essential material used for membrane fabrication and enhancement of membrane properties. Low-molecular-weight PEG sometimes is used as pore constrictor and pore former for developing MD membranes and support layer of FO membranes. Due to the affinity of PEG chains to water molecules, PEG, its derivatives, and copolymers have been widely used in the fabrication/modification of FO and MD membranes, which are currently applied to bioseparation, wastewater treatment, and desalination in academia and industry at the pilot scale. This chapter covers direct PEG and its membrane separation applications in wastewater treatment and desalination. The advancement of PEG in membrane science and engineering is reviewed and discussed comprehensively. We focus on the effectiveness of PEG on membrane antifouling and the stability of PEG-modified membranes when applied to wastewater treatment and desalination.
Part of the book: Polyethylene Glycol