Performance modeling and analysis of spent nuclear fuel recycling

The rapid expansion of nuclear energy in China has intensified concerns regarding spent fuel management. However, the consequences of failure or delay in developing approaches to managing spent fuel in China have not yet been explicitly analyzed. Thus, a dynamic analysis of transitions in nuclear fuel cycles in China to 2050 was conducted. This multi‐disciplinary study compares the environmental, security, and economic consequences of choices among ongoing technology development options for spent fuel management. Four transition scenarios were identified: the direct disposal of PWR (Pressurized Water Reactor) spent fuel, the recycling of PWR spent fuel through PWR‐MOX (Mixed Oxides), the PWR‐MOX followed by fast reactors, and the recycling of PWR spent fuel using fast reactors. Direct disposal would have the lowest cost of electricity generation under the current market conditions, while the reprocessing and recycling of PWR spent fuel would benefit the Chinese nuclear power program by reducing the generation of high level waste (67–82%), saving natural U resources (9–17%), and reducing Pu management risk (24–58%). Moreover, a fast reactor system would provide better performance than one‐time recycling through PWR‐MOX. The latter also poses high risks in managing the build‐up of separated Pu. Copyright © 2015 John Wiley & Sons, Ltd.     

Managing spent nuclear fuel in South Korea: Heterogeneous public attitudes toward different management strategies at individual- and segment levels

The management of spent nuclear fuel is a problem shared by countries that are operating nuclear power plants or have done so in the past. To implement socially agreed spent nuclear fuel management policies, it is necessary to recognize public attitudes and preferences toward policies. This study analyzed public preferences at the individual- and segment levels toward spent nuclear fuel management strategies in South Korea using a choice experiment and the hierarchical Bayesian normal mixture discrete choice model. Furthermore, it compared public acceptance for different types of management strategies using ex-ante simulation. Accordingly, the public was categorized into two groups. Segment 1 (31.62%) took a smaller proportion of the population than segment 2 (62.38%) and showed a higher degree of heterogeneity than segment 2. Segment 1 was more sensitive to increased electricity costs than segment 2 because of the implementation of spent nuclear fuel management policies and preferred a democratic process. Based on the results, we expect that the Korean government would receive public support when proceeding with the construction and operation of a permanent spent nuclear fuel repository facility. However, considering the degree of heterogeneity, governmental efforts to achieve social consensus are necessary.     

Simulation of thermal state of containers with spent nuclear fuel: multistage approach

The safe thermal conditions of spent nuclear fuel storage are the important component of complex safety of the dry spent nuclear fuel storage facility. The multistage approach for numerical definition of thermal fields in storage containers with spent fuel assemblies is proposed. The approach is based on solving of the series of the conjugate heat transfer problems with different geometrical detailing. The developed approach is used for estimation of thermal state of ventilated containers with spent nuclear fuel of WWER‐1000 reactors of Zaporizhska nuclear power plant. The results of the thermal calculations for single‐placed container on open‐site storage platform were presented. The safety of containers usage in normal and extreme ambient temperatures was proven. Copyright © 2015 John Wiley & Sons, Ltd.     

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。     

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.     

An energy management strategy based on dynamic power factor for fuel cell/battery hybrid locomotive

In order to efficiently absorb more regenerative braking energy which sustains much longer compared with the conventional vehicle, and guarantee the safety of the hybrid system under the actual driving cycle of locomotive, an energy management control based on dynamic factor strategy is proposed for a scale-down locomotive system which consists of proton exchange membrane fuel cell (PEMFC) and battery pack. The proposed strategy which has self-adaption function for different driving cycles aims to achieve the less consumption of hydrogen and higher efficiency of the hybrid system. The experimental results demonstrate that the proposed strategy is able to maintain the charge state of battery (SOC) better than Equivalent Consumption Minimization Strategy (ECMS), and the proposed strategy could keep the change trend of SOC, which the final SOC is closed to the target value regardless of the initial SOC of battery. Moreover, the hydrogen consumption has been reduced by 0.86g and the efficiency of overall system has been raised of 2% at least than ECMS under the actual driving cycle through the proposed strategy. Therefore, the proposed strategy could improve the efficiency of system by diminishing the conversion process of energy outputted by fuel cell.     

The economic competitiveness of promising nuclear energy system: A closer look at the input uncertainties in LCOE analysis

In this study, we aimed to provide important information about the potential economic benefits and risks of nuclear electricity generation associated with existing and prevailing nuclear technologies and to examine the economic effects of nuclear fuel cycle strategies in Korea. An economic analysis model that evaluates the overall life‐cycle costs of nuclear energy systems coupled with multiple fuel cycle options was specially developed by using the levelized cost of electricity (LCOE) as the fundamental methodology. This model is capable of identifying a range of techno‐economic uncertainties underlying each individual nuclear energy system taking into account the state of the art in fuel cycle technologies. It can also quantify and incorporate the resulting impacts into a system‐wide LCOE distribution for each fuel cycle option based on Monte Carlo probabilistic simulation. We analyzed and discussed examples of the economic performance of 13 promising candidates for nuclear energy systems integrated with extensive fuel cycle technologies (including one direct disposal and 12 specific reprocessing and recycling fuel cycle options). We also conducted a sensitivity analysis to investigate the major sensitivity factors of the system component cost in each fuel cycle option and their impacts on individual economic performances. Furthermore, a closer look at the techno‐economic uncertainties of advanced fuel cycle technologies in a break‐even analysis offers evidence of the potential economic feasibility and cost‐reduction opportunities in the reprocessing and recycling options relative to the direct disposal of spent nuclear fuel.     

A study of the probabilistic risk assessment to the dry storage system of spent nuclear fuel

Due to the large power supply in the energy market since 1960s, the nuclear power planets have been consistently constructed throughout the world in order to maintain and supply sufficient fundamental power generation. Up to now, most of the planets have been operated to a point where the spent fuel pool has reached its design capacity volume. To prevent the plant from shutdown due to the spent fuel pool exceeding the design capacity, the dry cask storage can provides a solution for both the spent fuel pool capacity and the mid-term storage method for the spent fuel bundles at nuclear power planet.     

Variable structure battery-based fuel cell hybrid power system and its incremental fuzzy logic energy management strategy

A hybrid power system consists of a fuel cell and an energy storage device like a battery and/or a supercapacitor possessing high energy and power density that beneficially drives electric vehicle motor. The structures of the fuel cell-based power system are complicated and costly, and in energy management strategies (EMSs), the fuel cell's characteristics are usually neglected. In this study, a variable structure battery (VSB) scheme is proposed to enhance the hybrid power system, and an incremental fuzzy logic method is developed by considering the efficiency and power change rate of fuel cell to balance the power system load. The principle of VSB is firstly introduced and validated by discharge and charge experiments. Subsequently, parameters matching of the fuel cell hybrid power system according to the proposed VSB are designed and modeled. To protect the fuel cell as well as ensure the efficiency, a fuzzy logic EMS is formulated via setting the fuel cell operating in a high efficiency and generating an incremental power output within the affordable power slope. The comparison between a traditional deterministic rules-based EMS and the designed fuzzy logic was implemented by numerical simulation in three different operation conditions: NEDC, UDDS, and user-defined driving cycle. The results indicated that the incremental fuzzy logic EMS smoothed the fuel cell power and kept the high efficiency. The proposed VSB and incremental fuzzy logic EMS may have a potential application in fuel cell vehicles.     

火电与核电的厂址选择及差异性分析

针对建设节约型企业的要求,对火电与核电的厂址选择的差异性进行了分析,以达到节约建设用地的目的,对建成节约型企业具有指导意义。     

On the reconstruction of the fisson products distribution in nuclear fuel rods

The maximum likelihood tomographic method is used to reconstruct the radioactive fission products distribution in irradiated fuel pins from a very small number of projections. The method can be used to analyse the behaviour of the nuclear fuel during irradiation and also to obtain an improvement in burn-up estimation. An experimental result, for a CANDU type fuel pin, is reported. A criterion for optimally stopping the iterative algorithm is suggested.     

Implementation of self-adaptive Harris Hawks Optimization-based energy management scheme of fuel cell-based electric power system

This paper presents a hybrid Fuel Cell-based Power System (FCPS) consisting of fuel cell and hybrid Energy Storage Systems (ESSs), including a battery with high energy density and supercapacitor with high power density to overcome the sudden load demand change and improving the reliability of the delivered power. Any hybrid power system needs Energy Management Strategies (EMS) to balance the power between the different energy sources. In this paper, a comparative analysis of three energy management strategies, including the state machine control method, the classical PI control method and equivalent consumption minimization strategy (ECMS) is performed. The paper's main objective is enhancing the DC-bus voltage profile of a hybrid fuel cell/battery/supercapacitor power system equipped with the developed under-mentioned EMS by using a hybrid modified optimization technique that combines Harris Hawks optimization (HHO) and Sine Cosine Algorithm (SCA). The new hybrid HHO-SCA is employed to determine the optimal control parameters of the DC-bus voltage controller, which significantly assists in enhancing the DC-bus voltage profile as well as the performance of the applicable ESS in terms of improving efficiency and SoC. The effectiveness of the suggested control schemes is simulated using MATLAB/SIMULINK software. The simulation results confirmed that the proposed HHO-SCA is superior and efficient in improving the DC-bus voltage.     

Application of Pontryagin's Minimal Principle to the energy management strategy of plugin fuel cell electric vehicles

This paper proposes an optimal real-time energy management strategy based on the Pontryagin's Minimal Principle (PMP) targeting at minimizing operation cost for a plug in proton electrolyte membrane (PEM) fuel cell city bus. The Dynamic Programming (DP) and PMP strategies are firstly deduced. Influences of the initial co-state value on the PMP strategy are analyzed. The DP, PMP, Charge Depleting Charge Sustaining (CDCS) and Blended strategies are compared in a simulation model. Results show that, major factors that influent the operation cost are the end value of battery State of Charge (SoC), the SoC trajectory curve, and the distribution of the working points of the fuel cell system. From a statistic viewpoint, the operation cost increases almost linearly with the end value of the SoC with a gradient of 1.41 Yuan.%⁻¹. Compared with a CDCS strategy, the operation cost can be reduced by 7.2% through taking the DP strategy, and by 5.9% through taking the PMP strategy. The PMP strategy leads to an operation cost that is 1.4% higher than the DP, but it is applicable in the real-time control system. An online energy management strategy based on PMP was set up and applied to an embedded controller. Tests in the 30 “China city bus typical cycles” showed that, the fuel economy was 5.8 kg (100 km)⁻¹, and the operation cost was 271.3 Yuan (100 km)⁻¹.     

The optimal fuel mix and redistribution of social surplus in the Korean power market

This paper investigates the difference between the optimal fuel mix incorporating a pre-installed generation capacity constraint and the actual fuel mix in the Korean power market. Since the restructuring of the market, the fuel mix has been determined partly by investors and partly by the Basic Plan for Long-Term Electricity Supply and Demand (BPE). Both the system marginal price (SMP), and the capacity payment (CP), which has been based on the fixed cost of a specific gas turbine generator, were intended to provide an investment incentive in the market; however, they did not bring about an optimal fuel mix in Korea. Under the circumstances of a shortage of base load generators, these generators may garner excessive profits due to a high SMP level. However, the adjustment scheme of profit between KEPCO and Gencos left scant profit for generators. This paper suggests that a contract is needed to create the appropriate profit and tax levels for these base load generators. The redistribution of profit improves equality between consumers and generators, and the proper margin creates incentives for base load technology investment in Korea.     

Development of new energy management strategy for a household fuel cell/battery hybrid system

This work aims to construct an efficient and robust fuel cell/battery hybrid operating system for a household application. The ability to dispatch the power demands, sustain the state of charge (SOC) of battery, optimize the power consumption, and more importantly, ensure the durability as well as extend the lifetime of a fuel cell system is the basic requirements of the hybrid operating system. New power management strategy based on fuzzy logical combined state machine control is developed, and its effectiveness is compared with various strategies such as dynamic programming (DP), state machine control, and fuzzy logical control with simulation. Experimental results are also presented, except for DP because of difficulties in achieving real‐time implementation and much faster response to load variation. The given current from the energy management system (EMS) as a reference of the fuel cell output current is determined by filtering out various harmful signals. The new power management strategy is applied to a 1‐kW stationary fuel cell/battery hybrid system. Results show that the fuel cell hybrid system can run much smoothly with prolonged lifetime.     

A review on the design and control strategy of energy storage system in wind power application

随着风力发电大规模入网,其随机性,波动性和间歇性特征对电力系统调频,调峰等有功平衡手段及电压稳定的影响越来越严重.储能系统能够在一定程度上控制风场的输出功率,平抑风电功率波动,改善风机低电压穿越能力,甚至为系统提供辅助服务,是从风场侧提高系统对风电的接纳能力的可行解决方案之一.作者在简要的介绍了风场储能技术应用现状的基础上,重点针对储能型风场内蓄电池储能系统的设计方案,容量优化及控制策略的研究现状及关键问题进行综述及探讨.     

A multi-agent system for energy management of distributed power sources

The field of energy management is an area increasingly studied. However, most solutions are based on centralized systems and barely fulfil criterion like fault tolerance or adaptability. Also, these systems are often difficult to design because of the “top–down” approach used: the designer generally knows how each component has to respond separately, but a centralized management system focuses his attention solely on the overall reaction of the system. That is why a distributed management solution based on the paradigm of Multi-Agent Systems (MASs) is proposed in this paper. In addition to a more natural conception, based on a “bottom–up” approach, this solution ensures better system reliability. After reviewing the previous works, an application of MAS to power management in a hybrid power source is presented. Then, the system is tested using a simulation model. The results show that this approach is perfectly valid and can respond to most problems of centralized energy management systems (EMSs).     

Performance assessment of a hybrid solid oxide and molten carbonate fuel cell system with compressed air energy storage under different power demands

As electricity demand can vary considerably and unpredictably, it is necessary to integrate energy storage with power generation systems. This study investigates a solid oxide and molten carbonate fuel cell system integrated with a gas turbine (GT) for power generation. The advanced adiabatic compressed air energy storage (AA-CAES) system is designed to enhance the system flexibility. Simulations of the proposed power system are performed to demonstrate the amount of power that can supply to the loads during normal and peak modes of operation under steady-state conditions. The pressure ratios of the GT and AA-CAES and the additional air feed are used to design the system and analyze the system performance. The results show that a small additional air feed to the GT is certainly required for the hybrid system. The GT pressure ratio of 2 provides a maximum benefit. The AA-CAES pressure ratio of 5 is recommended to spare some air in the storage and minimize storage volume. Moreover, implementation of the GT and AA-CAES into the integrated fuel cell system allows the system to cope with the variations in power demand.     

Sizing methodology for hybrid systems based on multiple renewable power sources integrated to the energy management strategy

This work presents a design methodology for a hybrid energy system based on multiple renewable power sources and bioethanol. The new concept of generation consists on having multiple power sources such as a PEM fuel cell system fed by the hydrogen produced by a bioethanol reformer and wind-solar sources working all together supervised by the energy management system. The necessary heating for the bioethanol reforming reaction can be provided by the renewable sources to enhance the efficiency of the hydrogen production. It is worth noting that, from the power balance as well as backup point of views, the hybrid system is equipped with energy storage devices. An optimal sizing methodology integrated with the energy management strategy is proposed here for designing the overall hybrid system. The suggested approach is based on genetic algorithms, using historical climate data and load demands over a period of one year. Several simulation results are given to show the methodology performance in terms of loss of power supply probability (LPSP), costs and bioethanol consumption.     

The study on the power management system in a fuel cell hybrid vehicle

This paper presents a model of a hybrid electric vehicle, based on a primary proton exchange membrane fuel cell (PEMFC) and an auxiliary Li-ion battery, and its dynamics and overall performance. The power voltage from the fuel cell is regulated by a DC/DC converter before integrating with the Li-ion battery, which provides energy to the drive motor. The driving force for propelling the wheels comes from a permanent magnet synchronous motor (PMSM); where the power passes through the transmission, shaft, and the differential.