Use Of Nuclear Fuels Research Articles

Calculation of the packing fraction in a pebble-bed ADS and redesigning of the Transmutation Advanced Device for Sustainable Energy Applications (TADSEA)

One of the main problems that should be addressed in the use of nuclear fuels for heat and electricity production is the management of nuclear waste from conventional nuclear power plants and its inventory minimization. Fast reactors and Accelerator Driven Systems (ADSs) are the main options for reducing the long-lived radioactive waste inventory.In previous studies, the conceptual design of a Transmutation Advanced Device for Sustainable Energy Applications (TADSEA) has been made. The TADSEA is a pebble-bed ADS cooled by helium and moderated by graphite; it uses as fuel small amounts of transuranic elements in the form of TRISO particles, confined in 3cm radius graphite pebbles. It has been conceived for Plutonium (Pu) and Minor Actinides (MA) transmutation and for achieving very high helium temperatures at the core's outlet to match the thermal requirements for hydrogen production by high temperature electrolysis (HTE) or by the iodine-sulfur (I–S) thermo-chemical cycle.In this paper, a geometrical method for calculating the real number of pebbles that fit in a cylindrical ADS core, according to its size and pebble configuration, is described. Based on its results, the packing fraction influence on the TADSEA's main work parameters is studied, and the redesign of the previous configuration is done in order to maintain the exit thermal power established in the preliminary design. Results have shown the capability of the system to reach coolant outlet temperatures high enough for its application to hydrogen production.

Actinide Selective Systems for Environmental Extraction and Sensing Applications

AbstractThe potential environmental and health concerns surrounding actinides and the use of nuclear fuels limits the acceptance of nuclear power by the public. This in turn, hinders the capability of this country to take advantage of nuclear power. Expanding our fundamental knowledge of actinide coordination chemistry will allow for the development of improved actinide sensors, new separations methods, or new means of radioactive waste remediation. We have designed and optimized a solution-phase parallel method for the synthesis of a library of symmetrical 2-quinoxalinol salens, Schiff-base type ligands with a 2-quinoxalinol incorporated into the salen backbone. This combines the rigid salen coordination framework with the quinoxaline properties that impart properties for use in colorimetric or fluorescent sensors. These have now been incorporated into organic soluble resins for metal extraction.

Electromagnetic energy and food processing.

The use of electromagnetic energy in food processing is reviewed with respect to food safety, nutritional quality, and organoleptic quality. The effects of nonionizing radiation sources such as microwave and radio-frequency energy and ionizing radiation sources, e.g. radioactive cobalt-60 and caesium-137, on the inactivation of microbes and nutrients are compared with those of conventional heating processes both in terms of their kinetic behavior and their mechanisms of interaction with foods. The kinetics of microwave and conventional thermal inactivation are considered for a generalized nth-order model based on time and temperature conditions. However, thermal inactivation effects are often modeled by 1st-order kinetics. Microbial and nutrient inactivation by ionizing sources are considered for a 1st-order model based on radiation dose. Both thermal and radiation resistance concepts are reviewed and some typical values of radiation resistance are given for sensitive vegetative bacterial cells, yeasts, and molds and for resistant bacterial spores and viruses. Nonionizing microwave energy sources are increasingly used in home and industrial food processing and are well-accepted by the American public. But, despite recent Food and Drug Administration approval of low and intermediate ionizing radiation dose levels for grains and other plants products and the fact that irradiated foods are sold in more than 20 countries of the world, public fears in the U.S. about nuclear energy may limit the role of ionizing radiation in food processing and preservation and may also limit the use of nuclear fuels as an alternate source of electrical energy.

Prospectives on the risks of alternative fuel cycles.

A commentary is provided on the uncertainties in the data and in qualifying the phenomena relating to the risks imposed by the various steps involved in the use of coal, oil, natural gas, hydropower, and nuclear fuels for the generation of electricity. Uncertainties appear to be extremely large for hydropower which exhibits both large scale ecological impacts and the potential for high consequence, moderate frequency events at specific sites. Major risk-related uncertainties with the use of nuclear fuels include those surrounding nuclear weapons proliferation and reactor accident frequencies and consequences. Uncertainties for coal and oil include specification of the damage function of air transported sulfates and the effects of atmospheric CO2 buildup, acid rain, and groundwater contamination from mine water runoff. Compounding these problems is the potential impact of the growing global competition for a diminishing supply of oil. In the studies reviewed herein, the assessed risks of the nuclear fuel cycle are no greater than those of the primary alternatives. Prudence suggests that we do not totally reject any particular option at this time on the basis of health effects alone; similarly, no option is an undisputed choice.

Nuclear power and the science curriculum

Because of the nature of the secondary school curriculum, i.e. its domination by examinations and examining boards, and its being consequently slow to evolve, science curricula can find themselves out of step with technological change in society. In view of this the use of nuclear fuels as an energy source is examined.

Safeguarding Atoms for Peace

Since 1945 the number of nations possessing nuclear weapons has increased five times and stockpiles of nuclear weapons have increased thousands of times. The enormity of the build-up of capabilities for nuclear destruction has largely overshadowed the remarkable progress that has been made since 1945 in developing the peaceful applications of nuclear science. The take-off point for the economic use of nuclear fuels for generating electricity appears to have now been reached.