Combustion Characteristics According to the Chemical Composition of Land Fill Gas

This study was conducted using the existing ignition device to verify the effectiveness of LFG, a renewable energy source. The experimental method used a constant volume combustion chamber to check the flame propagation process and combustion pressure. The experiment was carried out by changing the fuel composition ratio of LFG in the range of LFG70 to LFG40. From the result, it was found that the methane combustion occurred smoothly in LFG70 during the flame propagation process, and that combustion progressed gradually over time. In the LFG60 and LFG50 regions, which are fuels with a high CO2 ratio, it was confirmed that the combustion slowed down and the brightness of the light decreased at the same time. In LFG40 with 40% of CH4, a misfire phenomenon in which combustion does not occur was discovered. For combustion pressure, the CH4 chemical composition of the LFG was lowered, which led to the combustion delay and the reduction of combustion pressure

Assessment of Partitioning and Transmutation of High-Level Waste and Hypothetical Implementation Scenarios in Germany

In the context of the search for a deep geological repository for high-level radioactive waste from nuclear energy a preliminary waste treatment is repeatedly called into play by partitioning and transmutation (P&T). Proponents of this approach promise that with P&T, the requirements for and the risks posed by a – then still necessary – repository could be significantly reduced. However, such technological promises have to be prospectively, promptly and publicly reasonably verifiable. Partitioning is reprocessing in which, in addition to separating uranium and plutonium from the fission products, other material streams (for example, the minor actinides) are extracted. In transmutation, radionuclides – especially through nuclear fission – are converted into other nuclides. Thus, conversion of the parent nuclides into nuclides with shorter half-lives, lower radiotoxicity, or into stable nuclides could be achieved. For the assessment of P&T, essential aspects are the current degree of maturity of necessary technologies, the requirements for research and development, technological development risks, the basic feasibility and objective, risks of a hypothetical operation of corresponding plants and the possible effects on nuclear waste disposal. More specifically, on the technological side, it is all about development periods, technical security requirements and licensability, proliferation risks and implementation periods. The presentation of the results of some hypothetical P&T scenarios is intended to help to assess the impacts on radioactive waste present in Germany, necessary facilities and operating periods. Thus, pyro-chemical and hydrochemical separation processes, special transuranic fuels based on mixed oxides (MOX) or uranium-free fuel types and critical fast reactors, subcritical (accelerator-driven) reactors, as well as molten salt reactors, are considered. One difficulty is that the multiple recycling of the transuranics changes the fuel composition. Detailed statements about these changes are only possible with complex simulation calculations and their influence on safe reactor operation. So far, this has not happened on an international scale. In the modelling presented here, an attempt was made to represent the restrictions that the reactor design has on the fuel composition more precisely, at least insofar as the element composition of the fuel remains the same for the duration of the scenario. Conclusions presented from the analysis of the hypothetical scenarios affect, among other things, necessary operating periods and the number of plants and changes achieved in the stock of both transuranics and fission products.

Performance Improvement for Multi-recycling HTGR Incorporated with MA burning

Multi-recycling HTGR has been investigated by JAEA in order to reduce the environmental burden and non-proliferation of Pu. In the previous study, it is found that all actinoids except neptunium, which is not problematic from the viewpoint of toxicity and proliferation, can be recycled. However, the cycle length is slightly decreased compared with uranium fueled core due to the cumulated fertile TRU in the fuel composition. In the present study, Pu recycling HTGR is designed to incorporate with MA burning. As a result, the cycle length is increased by approximately 15% compared with TRU multi-recycling core, and if the MA burner can be achieved by IFR, the cost is decreased by 0.14 yen/kWh.