我国快堆闭式核燃料循环体系的现状及展望

基于铀资源需求和乏燃料积累预测,论证了我国发展快堆闲式核燃料循环的必要性,通过国内外调研,重点对影响我国快堆闭式循环的三个关键因素：钚元素积累、快堆技术、乏燃料后处理及快堆燃料技术的现状进行分析,并提出了展望和建议。     

Core design options of an ultra‐long‐cycle sodium cooled reactor with effective use of PWR spent fuel for sustainable energy supply

In this work, 350MWe ultra‐long‐cycle sodium‐cooled reactor cores are designed to supply electric energy over ~60 Effective Full Power Years (EFPYs) without refueling and with an effective use of Transuranics (TRU) and uranium from large pressurized water reactor (PWR) spent fuel stocks. The core employs the axial blanket‐driver‐blanket (ABDB) burning strategy, which was recently proposed by the authors to achieve an ultra‐long‐cycle length with self‐controllability under unprotected accidents. In particular, a thorium–uranium fuel cycle is considered to remove the heterogeneity of the fuel assemblies for design simplification and to improve the core performance parameters by selectively adding thorium into both blanket and driver fuels. The results show that the use of TRU nuclides from PWR spent fuel leads to significant extension of the fuel cycle length, but considerable increase of burnup reactivity swing. In addition, these results also indicate that the uranium–thorium mixed fuels both in the lower blanket and driver considerably improve the inherent safety of the ultra‐long‐cycle core by reducing burnup reactivity and sodium void worth; this makes it possible to simplify the previous heterogeneous fuel assembly design with improved core performances. Copyright © 2016 John Wiley & Sons, Ltd.     

解析中国的核能战略

分析了我国发展核电三步走的战略（第一步压水堆核电站,第二步快中子增殖堆电站和第三步核聚变堆电站）及发展核电所需要的铀资源储备（重视国内外的铀资源利用）,进而对核燃料循环中的乏燃料后处理及乏燃料处置分离和嬗变技术（加速器驱动的次临界系统ADS）进行了讨论。     

Power flattening study of ultra‐long cycle fast reactor using thorium fuel

This paper presents a design study of power shape flattening for an optimized ultra‐long cycle fast reactor with a power rate of 1000 MWe in order to mitigate the power peaking issue and improve the safety with a lower maximum neutron flux and reactivity swing. There are variations in the core designs by loading thorium fuel or zoning fuels in the blanket region and the bottom driver region of ultra‐long cycle fast reactor with a power rate of 1000 MWe. While it has lower breeding performance in a fast breeder reactor, thorium fuel is one of the promising fuel options for future reactors because of its abundance and its safety characteristics. It has been confirmed that the thorium fuels, when loaded into the center region of a reactor core, lower the power peaking factor from 1.64 to 1.25 after 20 years and achieves a more flattened radial power distribution. This consequently reduces the maximum neutron flux and the speed of the active core moving from 3.0 cm/year to 2.5 cm/year on the average over the 60‐year reactor operation. It has been successfully demonstrated that the three‐zone core is the most optimized core, has the most flattened radial power shape, and is without any compromise in the nature of long cycle core, from the neutronics point of view, in terms of average discharge burnup and breeding ratio. Copyright © 2016 John Wiley & Sons, Ltd.     

Solid oxide fuel cell technology for sustainable development in China: An over-view

Fuel cell technology motivates a variety of benefits, which are barely offered by other energy technologies. The fuel cell can be obtained through natural resources—biomass, coal and water, which are abundant in China. More importantly, most of these are sustainable and realize ecological circulation. Being blessed with a source of renewable energy, fuel cell technology is favorably promoted in China. Simultaneously, fuel cell technology offers China great opportunities to meet the energy consumption demand for its sustainable development. In this proposed method, useful results of leading research in solid oxide fuel cell relevant research in China are reviewed and the hybrid system based fuel cell technology is particularly detailed. Additionally, the effects of some important renewable energy parameters, future challenges and constructive recommendations for China's energy technology are suggested.     

我国核裂变能可持续发展战略研究

本文从科学技术的角度,分析我国国民经济增长对核能发展的需求,探讨我国核能的近中期发展战略构想,指出为实现其发展战略目标而应重点研究的关键科学技术与问题,并提出一些相关的政策建议,为国家制定核能中长期发展规划提供参考。     

Market perspectives of stationary fuel cells in a sustainable energy supply system—long-term scenarios for Germany

Because of high efficiency, low environmental impacts and a potential role in transforming our energy system into a hydrogen economy, fuel cells are often considered as a key technology for a sustainable energy supply. However, the future framing conditions under which stationary fuel cells have to prove their technical and economic competitiveness are most likely characterised by a reduced demand for space heating, and a growing contribution of renewable energy sources to heat and electricity supply, which both directly limit the potential for combined heat and power generation, and thus also for fuel cells. Taking Germany as a case study, this paper explores the market potential of stationary fuel cells under the structural changes of the energy demand and supply system required to achieve a sustainable energy supply. Results indicate that among the scenarios analysed it is in particular a strategy oriented towards ambitious CO₂-reduction targets, which due to its changes in the supply structure is in a position to mobilise a market potential that might be large enough for a successful fuel cell commercialisation. However, under the conditions of a business-as-usual trajectory the sales targets of fuel cell manufacturers cannot be met.     

Dynamic simulation of a space gas-cooled reactor power system with a closed Brayton cycle

Space nuclear reactor power (SNRP) using a gas-cooled reactor (GCR) and a closed Brayton cycle (CBC) is the ideal choice for future high-power space missions. To investigate the safety characteristics and develop the control strategies for gas-cooled SNRP, transient models for GCR, energy conversion unit, pipes, heat exchangers, pump and heat pipe radiator are established and a system analysis code is developed in this paper. Then, analyses of several operation conditions are performed using this code. In full-power steady-state operation, the core hot spot of 1293 K occurs near the upper part of the core. If 0.4 $ reactivity is introduced into the core, the maximum temperature that the fuel can reach is 2059 K, which is 914 K lower than the fuel melting point. The system finally has the ability to achieve a new steady-state with a higher reactor power. When the GCR is shut down in an emergency, the residual heat of the reactor can be removed through the conduction of the core and radiation heat transfer. The results indicate that the designed GCR is inherently safe owing to its negative reactivity feedback and passive decay heat removal. This paper may provide valuable references for safety design and analysis of the gas-cooled SNRP coupled with CBC.     

The energy situation and its sustainable development strategy in China

The paper briefly summarizes China’s energy situation and sustainable development strategy as they were by 2009. The energy consumption in 2009 is reported to be 3.1 billion tons standard coal equivalent, 1/7 of the world total, 6.3% higher than in the year 2008, and its share of world CO₂ emissions increased rapidly to 20.3% in 2006. These trends are most likely to continue with China’s plan to accomplish its social and economy development goals. To address these problems and also respond to increasing world pressure for reduction of greenhouse gas emissions, the Chinese government plans and has legislated promotion of energy conservation, efficiency, renewable energy technologies and use, and reduction of energy-related environmental impacts to reduce energy intensity by 20% during the 2006-2010 period, and to reduce the CO₂ emission/GDP ratio by 40-45% by 2020 relative to 2005. China is facing severe energy-related challenges that conflict resources shortages with the planned rapid economic development, energy use with the related environmental pollution, and new technology with the old production/consumption patterns. It is recognized that energy development must, however, follow a sustainable path to coordinate economy growth, social development, and environmental protection.     

Rural energy and fuel forests in China

The structure of rural energy consumption for living (domestic) in China is presented based on the nationwide survey conducted from 1986 to 1987. The fuelwood energy consumed amounted to 29% of the totally consumed living energy. The average deficit of fuelwood supply was about 25% for the whole country. The reasonable exploitation of fuelwood resource was 265 Mm³, while the actual fuelwood consumption was 355 Mm³. A fuelwood demand of 443 Mm³ by 2000 was predicted based on a model. Another 4.2 Mha of fuel forests need to be established. The main problems existing in the management and utilization of fuel forests in China are analyzed, and some recommendations are presented.     

Reduction of energy consumption in biodiesel fuel life cycle

Essential requirements for biofuel are that (a) it should be produced from renewable raw material, and (b) it should have a lower negative environmental impact than that of fossil fuels. Apart from direct assessment of the engine emissions, environmental impact is also determined by performing life cycle analysis. Life cycle energy balance depends on specific climatic conditions and the agro- and processing technologies used. Rapeseed oil methyl ester life cycle energy ratios in Lithuanian conditions have been calculated as a function of rapeseed productivity, oil pressing and transesterification technologies used.Opportunities to improve biodiesel fuel life cycle energy efficiency, by implementing new technologies in agriculture as well as in industrial processing, were reviewed. The effectiveness of new technologies was evaluated on the basis of energy balance comparison.     

小型离心式压气机压缩氦气闭式循环的初步研究

介绍了小型离心式压气机闭式循环实验台的组成,并在此实验台上进行了压缩氦气和压缩空气闭式循环的实验,针对实验所得数据进行整理和理论分析,得到了压气机压缩氦气的特性线,并且利用压缩空气和压缩氦气的对比实验结果,初步分析了同一压气机压缩不同工质的相似现象。     

Thorium utilization in a small modular molten salt reactor with progressive fuel cycle modes

The thorium‐uranium (Th‐U) fuel cycle is considered as a potential approach to ensure a long‐term supply of nuclear fuel. Small modular molten salt reactor (SMMSR) is regarded as one of the candidate reactors for Th utilization, since it inherits the merits of both MSR and small modular reactor. The Th utilization in a 220‐MWe SMMSR with the once‐through fuel cycle mode is investigated first. Then, the SMMSR with batch and online fuel processing modes is investigated second for comparison, considering the progressive development of fuel reprocessing technology. To keep a negative temperature reactivity feedback coefficient (TRC), a configuration for fuel salt volume fraction (SVF) equal to 15%, with a mixed fuel of low enriched uranium (LEU) and thorium at an operation time of 5 years is recommended for the once‐through mode, corresponding to the Th energy contribution (ThEC) of 37.6% and natural U and Th utilization efficiency (UE) of 0.51%. Considering the solubility limit of heavy nuclide (HN) proportion (below 18.0 mol%) in the fuel salt, the total operation time of the SMMSR shall be less than 50 years for the batch reprocessing mode with a 5‐year reprocessing interval time. In this case, the ThEC and UE can be improved to about 47.4% and 0.99%, respectively. Finally, the Th utilization and fuel sustainability are analyzed at a lifetime of 50 years for the online reprocessing fuel cycle mode, including both the only online fission products (FPs) removing scheme and the fuel transition scheme from LEU to ²³³U. For the former scheme, the ThEC and UE can be further improved to 58.6% and 1.52%, respectively. For the latter scheme, ²³³Pa is extracted continuously from the core to breed and store ²³³U. If a total reactor lifetime of 50 years is assumed, the operation time using LEU as starting and feeding fuel for 6 years is required, and the bred ²³³U during this 6‐year operation can start and maintain the reactor criticality for the remaining 44 years. In this case, the ThEC is improved significantly to 89.1% corresponding to a UE of 2.74%.     

West Germany's efforts to close the nuclear fuel cycle: Strategies for radioactive waste management

West Germany's efforts to reach a mature nuclear economy by [closing] the [back end] of the nuclear fuel cycle are discussed with special emphasis on radioactive waste management strategies. the radioactive wastes that would be generated in a closed nuclear fuel cycle are described. A brief discussion is given of the motives that underlie the current international disagreement regarding the desirability of, and the need for, closing the nuclear fuel cycle. West Germany's concept for closing the nuclear fuel cycle is outlined including institutional arrangements and responsibilities. A discussion of radioactive waste classification follows. Expected volumes and inventories of radioactive wastes are pointed out. Current practices, and research and development work in the treatment and disposal of radioactive wastes are outlined. A final section is devoted to the history, circumstances and implications of the current requirement for a [solution] for the back end of the nuclear fuel cycle as a precondition for continued expansion of nuclear power in West Germany.     

Future regional nuclear fuel cycle cooperation in East Asia: Energy security costs and benefits

Economic growth in East Asia has rapidly increased regional energy, and especially, electricity needs. Many of the countries of East Asia have sought or are seeking to diversify their energy sources and bolster their energy supply and/or environmental security by developing nuclear power. Rapid development of nuclear power in East Asia brings with it concerns regarding nuclear weapons proliferation associated with uranium enrichment and spent nuclear fuel management. This article summarizes the development and analysis of four different scenarios of nuclear fuel cycle management in East Asia, including a scenario where each major nuclear power user develops uranium enrichment and reprocessing of spent fuel individually, scenarios featuring cooperation in the full fuel cycle, and a scenario where reprocessing is avoided in favor of dry cask storage of spent fuel. The material inputs and outputs and costs of key fuel cycle elements under each scenario are summarized.     

The analysis on energy and environmental impacts of microalgae-based fuel methanol in China

The whole life of methanol fuel, produced by microalgae biomass which is a kind of renewable energy, is evaluated by using a method of life cycle assessment (LCA). LCA has been used to identify and quantify the environment emissions and energy efficiency of the system throughout the whole life cycle, including microalgae cultivation, methanol conversion, transport, and end-use. Energy efficiency, defined as the ratio of the energy of methanol produced to the total required energy, is 1.24, the results indicate that it is plausible as an energy producing process. The environmental impact loading of microalgae-based fuel methanol is 0.187mPET₂₀₀₀ in contrast to 0.828mPET₂₀₀₀ for gasoline. The effect of photochemical ozone formation is the highest of all the calculated categorization impacts of the two fuels. Utilization of microalgae an raw material of producing methanol fuel is beneficial to both production of renewable fuels and improvement of the ecological environment. This Fuel methanol is friendly to the environment, which should take an important role in automobile industry development and gasoline fuel substitute.     

Integrated energy strategy for the sustainable development of China

We propose in this paper an integrated energy strategy based on a systems approach to address the energy challenges and energy dilemma in China. First, we give a review of existing approaches to energy planning and strategic management, followed by a discussion on the major relationships among energy, economical, environmental and societal systems. Next, we present a conceptual system model with alternative solutions and clarify corresponding concepts. Based on the results, we propose, summarize, and present strategic ideas as policy implications for China’s decision makers. In conclusion, we determine that China should enhance strategic planning and regulation from a life cycle viewpoint of the whole society, prioritize energy saving, continuously improve incumbent energy, and rationally develop alternative energy.     

Life cycle energy,environment and economic assessment of soybean-based biodiesel as an alternative automotive fuel in China

Life cycle energy, environment and economic assessment for conventional diesel (CD) and soybean-based biodiesel (SB) in China was carried out in this paper. The results of the assessment have shown that compared with CD, SB has similar source-to-tank (StT) total energy consumption, 76% lower StT fossil energy consumption, 79% higher source-to-wheel (StW) nitrogen oxides (NO_X) emissions, 31%, 44%, 36%, 29%, and 67% lower StW hydrocarbon (HC), carbon monoxide (CO), particulate matter (PM), sulfur oxides (SO_X), and carbon dioxide (CO₂) emissions, respectively. SB is thus considered to be much more renewable and cleaner than CD. However, the retail price of SB at gas stations would be about 86% higher than that of CD without government subsidy according to the cost assessment and China had to import large amount of soybean to meet the demand in recent years. Therefore, although SB is one of the most promising clean and alternative fuels, currently it is not a good choice for China. It is strategically important for China to diversify the feedstock for biodiesel and to consider other kinds of alternative fuels to substitute CD.     

A ‘must-go path’ scenario for sustainable development and the role of nuclear energy in the 21st century

An increase in the world population has accelerated the consumption of fossil fuels and deepened the pollution of global environment. As a result of these human activities, it is now difficult to clearly guarantee the sustainable future of humankind. An intuitional ‘must-go path’ scenario for the sustainable development of human civilization is proposed by extrapolating the human historical data over 30 years between 1970 and 2000. One of the most important parameters in order to realize the ‘must-go path’ scenario is the sustainability of energy without further pollution. In some countries an expanded use of nuclear energy is advantageous to increase sustainability, but fast reactor technology and closed fuel cycle have to be introduced to make it sustainable. In other countries, the development of cost-effective renewable energy, and the clean use of coal and oil are urgently needed to reduce pollution. The effect of fast nuclear reactor technology on sustainability as an option for near-term energy source is detailed in this paper. More cooperation between countries and worldwide collaboration coordinated by international organizations are essential to make the ‘must-go path’ scenario real in the upcoming 20 or 30 years.     

Life cycle study of coal-based dimethyl ether as vehicle fuel for urban bus in China

With life cycle assessment (LCA) methodology, a life cycle model of coal-based dimethyl ether (CBDME) as a vehicle fuel is established for China. Its life cycle from well to wheel are divided into three phases. They are feedstock extraction, fuel production and fuel consumption in vehicle. The primary energy consumption (PEC) and global warming potential (GWP) of CBDME pathway are analyzed and compared with coal-based diesel (CBD) as a latent rival to replace conventional petroleum-based diesel (CPBD).