Utilization Of Nuclear Energy Research Articles

Comparative Evaluation on Several Reactor Type of Actinide Closed-Cycle Schemes

Naturally, nuclear fuel resources are coming from uranium and thorium fuels for nuclear energy utilization. As by product reactor operation, some spent nuclear nuclear are produce which can be optimized by optimum recycled fuel option, as well as new fuel resource to increases fuel sustainabililty aspect of nuclear fuel. Several nuclear reactor types and the utilization of some recycled fuel options from their spent nuclear fuel as well as fuel breeding cabalitiy of the reactor based on those uranium and thorium fuel cycles. Some important parameters have been analyzed such as reactor performance of criticality and fuel conversion as well as some actinide productions in the present evaluation based on several fuel cycle schemes. As a basic recycling scheme, an open and a closed-fuel cycle of some actinides was used based on water-cooled reactor system, including ligh water and heavy water coolant. Basic analysis of the system is based on an equilibrium burnup calculation for the present computational approach analysis. Once through case requires more fissile materials than MOX fuel scheme to maintain criticality condition and heavy water coolant requires more fissile material than light water coolant for UOX fuel case, however, it shows the opposite trend for in case of MOX fuel. Thorium cycle requires more fissile material of U-233 for heavy water coolant than light water coolant. In term of light water case, the required fissile material of U-233 is less for thorium case than fissile material of U-235 in MOX fuel case. Fuel conversion ratios are obtained less than unity except for heavy water coolant of MOX fuel case, which obtains slightly more than unity. Thorium fuel shows better fuel breeding capability as well as heavy water coolant, which gives more fuel conversion capability than light water coolant. Actinide compositions of plutonium gives more than 1% for light water coolant and more than 10% for heavy water coolant case. For different fuel scheme cases, it shows that plutonium recycled scheme as MOX fuel case gives higher production of actinide or trans-uranium actinides from neptunium up to Curium than UOX fuel case for H2O coolant. Total even mass plutonium isotope produces higher than total odd mass plutonium isotope for both coolants and heavy water coolant produces more than its production for light water coolant. Better composition of even mass plutonium has shown better proliferation resistant level which is shown by plutonium recycled scheme and heavy water coolant case.

Enhancing and Development of Human Resources Capabilities for Nuclear Facilities in the Arab Countries Embarking on Nuclear Programs.

To achieve and maintain high levels of safety and security in nuclear facilities, these facilities must be staffed with an adequate number of highly qualified and experienced manpower and workforce who are duly aware of the technical and management requirements of safe operation. The main challenge facing countries embarking on nuclear power is to enhance the capacity building and human resources. This paper presents a regional strategic road map to enhance and strengthen human resources capabilities in Arab Countries (ACs) embarking on nuclear power programs,which is the case of United Arab Emirates (UAE), Egypt and Jordan. This strategic road map could be applied by establishing an Integrated Regional Administrative System (IRAS) within the frameworkof the Arab Network for Nuclear Regulators (ANNuR). The main objectives of this system are to activate, support and enhance capacity building and human resources development programs. This system could be administrated under the umbrella and supervision of both AAEA (Arab Atomic Energy Authority) and IAEA. This paper discusses and formulates a framework for the various aspects and structural componentsof this system. Egypt regulatory capabilities regarding nuclear and radiological regulatory activities are reviewed. The paper outlines and discusses the goals and capabilities of the AAEA and ANNuR regardingsupporting IRAS objectives. Challenges and needs of ACs regarding nuclear energy utilization are reviewed. Emphasis is focused on Safety and Security (S&S) issues in ACs, and IRAS capabilities and its role for supporting and assisting ACs embarking on nuclear power.

High burn-up operation and MOX burning in LWR; Effects of burn-up and extended cooling period of spent fuel on vitrification and disposal

ABSTRACT Looking ahead to final disposal of high-level radioactive waste arising from further utilization of nuclear energy, the effects of high burn-up of light-water reactors (LWR) with UO2 and MOX fuel and extended cooling period of spent fuel on waste management and disposal were discussed. It was assumed that the waste loading of waste glass is restricted by three factors: heat generation rate, MoO3 content, and platinum group metal content. As a result of evaluation for effects of extended cooling period, the waste loading of waste glass from both UO2 and MOX spent fuel could be increased in the current vitrification technology. For the storage of waste glass from MOX spent fuel with higher waste loading, however, those waste glass require long storage period prior to geological disposal because decay heat of 241Am contributes significantly. Therefore, the evaluation of effects of Am separation on the storage period was performed. Furthermore, heat transfer calculation was carried out in order to evaluate the temperature of buffer material in a geological repository. The results showed, 70 to 90% of Am separation is sufficiently effective in terms of thermal feasibility of a repository.

Synthesis of rod-like metal-organic framework (MOF-5) nanomaterial for efficient removal of U(VI): batch experiments and spectroscopy study

With the widespread application of radionuclide 235U(VI), it is inevitable that part of U(VI) is released into the natural environment. The potential toxicity and irreversibility impact on the natural environment has become one of the most forefront pollution problems in nuclear energy utilization. In this work, rod-like metal-organic framework (MOF-5) nanomaterial was synthesized by a solvothermal method and applied to efficiently adsorb U(VI) from aqueous solutions. The batch experimental results showed that the sorption of U(VI) on MOF-5 was strongly dependent on pH and independent of ionic strength, indicating that the dominant interaction mechanism was inner-sphere surface complexation and electrostatic interaction. The maximum sorption capacity of U(VI) on MOF-5 was 237.0 mg/g at pH 5.0 and T = 298 K, and the sorption equilibrium reached within 5 min. The thermodynamic parameters indicated that the removal of U(VI) on MOF-5 was a spontaneous and endothermic process. Additionally, the FT-IR and XPS analyses implied that the high sorption capacity of U(VI) on MOF-5 was mainly attributed to the abundant oxygen-containing functional groups (i.e., CO and CO). Such a facile preparation method and efficient removal performance highlighted the application of MOF-5 as a candidate for rapid and efficient radionuclide contamination’s elimination in practical applications.

Conceptual design and preliminary performance analysis of a hybrid nuclear-solar power system with molten-salt packed-bed thermal energy storage for on-demand power supply

In support of more efficient utilization of solar and nuclear energy in power generation, the present work proposes a conceptual design of a hybrid nuclear-solar power system (HNSPS) for on-demand power supply, based on a parallel thermal integration of small modular reactors with commercialized molten-salt concentrating solar power tower plants. A cost-effective thermal energy storage system is employed as a thermal coupling and a heat dispatcher to coordinate both nuclear heat and solar heat with power demands. The overall configuration and operation strategy of the hybrid system are elaborated. A numerical model of the hybrid system is developed based on the circulation of molten-salt. Using the model, a 7-day performance analysis of the hybrid system with different considerations are conducted. Effects of key design parameters on system performances are investigated by a parametric study. A customized evaluation parameter, named as “design score”, is defined to assess the suitability of the designed configurations. The performance analysis shows that the integration of nuclear power with concentrating solar power allows the system to be less dependent on heat dispatch to achieve required power regulations, comparing to a standalone CSP plant with an equivalent power capacity. The parametric study indicates that a higher heat generation utilization of the hybrid system requires a larger TES and a smaller heliostats field, while a higher power supply efficiency of the hybrid system is accompanied with a larger TES, a larger heliostats field, and a higher nuclear power capacity proportion. The optimum design configuration of a 200 MWe HNSPS is estimated to have a nuclear power capacity proportion of 50%, a theoretical thermal energy storage duration of 14.8 h, and a heliostats field with a solar multiple of 1.27. This configuration can completely satisfy the power demand without any heat generation curtailment during the 7-day operation. The obtained results allow the HNSPS to be considered as a promising non-carbon-emitting power generation system for on-demand power supply.

ENERGI NUKLIR SEBAGAI SOLUSI UNTUK MENGHAMBAT PEMANASAN GLOBAL

Global warming is the increase in the average temperature of the earth surface, atmosphere and oceans.The global warming in recent years has been international issues. The issues come to the surfacebecause global warming has the very big impact to the world and the lives of animal, plant and human,such as world climate change. The main cause of global warming is the combustion of fossil fuel suchas coal, oil and natural gas, that released carbon dioxide and other gases to atmosphere as greenhousegases. One of alternative to retard this global warming is by replacing fossil fuel with utilization of nuclearenergy for power plant. As a comparison, a 1,000 MWe nuclear power plant as a substitute for coal fi redpower plant at the same capacity, will reduce 6,000,000 tons of CO2 gas emission per year. Consideringenvironmental aspect, the nuclear power plant is not emitting CO2 gas, so that the use of nuclear powerplant can retard the global warming. Considering economic aspect, based on operational experienceof nuclear power plants in advanced countries, it is shown that cost of generating electricity of nuclearpower plants is more competitive than fossil fuel power plant. Considering safety aspect, nuclear powerplant operating in the world, have passed by a technological test. They have also an excellent operationreliability and a very good safety system.

Neutron dose rate analysis on HTGR-10 reactor using Monte Carlo code

The HTGR-10 reactor is cylinder-shaped core fuelled with kernel TRISO coated fuel particles in the spherical pebble with helium cooling system. The outlet helium gas coolant temperature outputted from the reactor core is designed to 700 °C. One advantage HTGR type reactor is capable of co-generation, as an addition to generating electricity, the reactor was designed to produce heat at high temperature can be used for other processes. The spherical fuel pebble contains 8335 TRISO UO2 kernel coated particles with enrichment of 10% and 17% are dispersed in a graphite matrix. The main purpose of this study was to analysis the distribution of neutron dose rates generated from HTGR-10 reactors. The calculation and analysis result of neutron dose rate in the HTGR-10 reactor core was performed using Monte Carlo MCNP5v1.6 code. The problems of double heterogeneity in kernel fuel coated particles TRISO and spherical fuel pebble in the HTGR-10 core are modelled well with MCNP5v1.6 code. The neutron flux to dose conversion factors taken from the International Commission on Radiological Protection (ICRP-74) was used to determine the dose rate that passes through the active core, reflectors, core barrel, reactor pressure vessel (RPV) and a biological shield. The calculated results of neutron dose rate with MCNP5v1.6 code using a conversion factor of ICRP-74 (2009) for radiation workers in the radial direction on the outside of the RPV (radial position = 220 cm from the center of the patio HTGR-10) provides the respective value of 9.22E-4 μSv/h and 9.58E-4 μSv/h for enrichment 10% and 17%, respectively. The calculated values of neutron dose rates are compliant with BAPETEN Chairman’s Regulation Number 4 Year 2013 on Radiation Protection and Safety in Nuclear Energy Utilization which sets the limit value for the average effective dose for radiation workers 20 mSv/year or 10μSv/h. Thus the protection and safety for radiation workers to be safe from the radiation source has been fulfilled. From the result analysis, it can be concluded that the model of calculation result of neutron dose rate for HTGR-10 core has met the required radiation safety standards.

Quantitative analysis on the impact of nuclear energy supply disruption on electricity supply security

Improvement of power supply security is of paramount importance to sustain human activities. Technical and engineering failures of power grid system have been analyzed to evaluate power system reliability hitherto. However, after Fukushima nuclear accident, the sudden electricity supply disruption particularly associated with nuclear energy utilization brings upon a new risk of electricity supply security arising from societal issues, or nuclear vulnerability. As such, a methodology of quantifying nuclear vulnerability is firstly established under varying both the magnitude and time instant of sudden stoppage of nuclear power operation. Through the nuclear vulnerability analysis, a new electricity supply security index dedicated for nuclear power utilization, named System Interruption Nuclear Vulnerability Index (SINVI) is developed. SINVI could be used to predict the risk of electricity supply disruption arising from the sudden stoppage of nuclear power operation corresponding to the different capacity combination of various energy sources. Finally, the widely proposed dimensions of energy security for undisturbed electricity supply – diversification and redundancy – are incorporated with nuclear vulnerability to design the more secured power system taking into account the risk of nuclear energy utilization. The established algorithm can be readily implemented in any other electricity grid network including nuclear power technology.

Study Neutronic of Small Pb-Bi Cooled Non-Refuelling Nuclear Power Plant Reactor (SPINNOR) with Hexagonal Geometry Calculation

Nuclear reactor technology is growing rapidly, especially in developing Nuclear Power Plant (NPP). The utilization of nuclear energy in power generation systems has been progressing phase of the first generation to the fourth generation. This final project paper discusses the analysis neutronic one-cooled fast reactor type Pb-Bi, which is capable of operating up to 20 years without refueling. This reactor uses Thorium Uranium Nitride as fuel and operating on power range 100-500MWtNPPs. The method of calculation used a computer simulation program utilizing the SRAC. SPINNOR reactor is designed with the geometry of hexagonal shaped terrace that radially divided into three regions, namely the outermost regions with highest percentage of fuel, the middle regions with medium percentage of fuel, and most in the area with the lowest percentage. SPINNOR fast reactor operated for 20 years with variations in the percentage of Uranium-233 by 7%, 7.75%, and 8.5%. The neutronic calculation and analysis show that the design can be optimized in a fast reactor for thermal power output SPINNOR 300MWt with a fuel fraction 60% and variations of Uranium-233 enrichment of 7%-8.5%.

Investigation of an integrated hydrogen production system based on nuclear and renewable energy sources: Comparative evaluation of hydrogen production options with a regenerative fuel cell system

Hydrogen has risen as a sustainable and efficient energy carrier option in reducing environmental pollution, and is seen as a potential solution for the current energy crisis. Hydrogen production via water decomposition is a potential process for direct utilization of nuclear thermal energy to increase efficiency and thereby facilitate energy savings. While many of the available renewable energy resources are limited due to their reliability, quality, quantity and density, nuclear energy has the potential to contribute a significant share of energy supply with very limited impacts to climate change. The proposed model in this study is an integrated hydrogen production system combining both nuclear and solar energy sources. This integrated system includes storage of hydrogen and its conversion to electricity by a regenerative fuel cell system when needed. There are many matured water splitting processes that can be linked with the nuclear and solar energy sources to decompose water to its constituents, among which is hydrogen. In this regard, a comparative study is carried out to evaluate an optimal and feasible hydrogen production/storage process with a regenerative fuel cell that can be linked to this integrated system. Studies conducted here on hydrogen production processes show the thermochemical water decomposition to be the better option for producing hydrogen, comparing to electrolysis, due to its high efficiencies and low costs. Energy and exergy efficiencies of various hydrogen production processes, and fuel cell systems are evaluated and compared. Also, a parametric study is conducted on these efficiencies to see the effect of various operating conditions.

Surface functionalization graphene oxide by polydopamine for high affinity of radionuclides

Abstract The utilization of nuclear energy plays an important role in our energy system; however, the leaking of radionuclides has potential threat to human health. In this paper, two-dimensional polydopamine/graphene oxide (PD/GO) composites were synthesized through a simple bio-inspired surface functionalization process by self-polymerization of dopamine monomers on GO surface. To evaluate the adsorption performance of PD/GO composites, the adsorbent was applied to remove uranium(VI) from aqueous solutions. Based on the Langmuir's equation, the maximum adsorption capacity was calculated to be 145.39 mg · g−1 by PD/GO composites, which is higher than that of pure PD (34.21 mg · g−1) and GO (75.71 mg · g−1). The enhanced adsorption capacity was mainly ascribed to the synergistic effect of PD with multifunctional groups and GO with high surface area. The adsorption process fitted well with the Langmuir adsorption isotherm and a pseudo-second order kinetics. Moreover, adsorption and regeneration experiment proved the samples can support long-term use in nuclear waste management. This work provides a convenient and promising materials for the removal of U(VI) from polluted water.

Europe's Road to a Sustainable Energy-Supply System

This paper examines how power generation in the European Union (EU) can be modernised along the lines of a sustainable solution pursuant to WEC principles. This means a re-design with the goal of implementing the EU's internal market and far-reaching decarbonisation. The example of Germany's energy U-turn shows one possible route, one that is marked by a massive expansion of renewable energies coupled with a phase-out of nuclear energy. Other European countries are pursuing different strategies. Current developments show that solutions chosen in any one country have direct implications for its neighbours. This is because electricity markets are continuing to grow together. In a spirit of solidarity between the member states, the closest possible review and coordination and/or harmonisation of policies are needed. This will allow the conversion process, which is associated with macroeconomic costs, to be shaped on a cost-efficient basis. For utilities, the energy turnaround brings with it a multitude of challenges. Utilities must convert their generation portfolio and, in particular, perceptibly increase their share of low-carbon energies. Conventional power plants must be designed flexibly, so that – besides volatility in consumption – fluctuations in the feed-in of renewable energies, too, can be offset. In addition to this technical requirement, energy suppliers are facing a situation in which the utilisation period of conventional power stations is falling as a result of the growing feed-in of renewables. On top of this comes the fact that wholesale electricity prices on sunny days are pushed down despite high demand owing to the growing feed-in of electricity from photovoltaic systems. Both factors limit the options for obtaining the necessary contributions to cover fixed costs on the market. This raises the issue of the market design of the future. The launch of capacity mechanisms, ie remuneration for the product ‘firm capacity’ supplementing the income obtained from the sale of electricity, could help. At the same time, capacity mechanisms could be a suitable instrument for coping with power failures. This brings politics into the game. With electricity markets growing together, the central requirement to be met by a capacity-market mechanism is that harmonised regulations, a discrimination-free design and technology neutrality are ensured throughout Europe. This is regarded as indispensable for creating a level playing field. Also as regards reaching the goal of Europe's climate policy, viz. a lowering of greenhouse-gas emissions by at least 80% by 2050 compared with 1990, the rule must be to prioritise European solutions over any national regulation. In addition, a procedure in climate policy that is more stringently reviewed at international level is considered unavoidable. Cost efficiency in reaching climate goals means backing market instruments. CO2 emissions trading should be accorded the role of leading instrument in climate protection. The instrument can be used to achieve agreed quantity targets for CO2 emissions reliably and at the least possible costs. One argument in favour of anchoring the trade in emissions as leading instrument to shape a sustainable energy supply is that the costs of transforming the energy system can be kept within bounds. Renewable energies enter the system with rising CO2 prices on a market-driven basis. The various technologies compete with one another and with other CO2- avoidance technologies, like increases in efficiency, utilisation of nuclear energy and CO2 capture and storage (CCS). One current study says that the expected growth in electricity consumption in the EU by some 1,000 TWh by 2050 will be covered by adding renewable energies if the focus is on trade in emissions as leading instrument. This doubles the share of renewables in power generation by 2050 to about 50%. After 2030, with rising CO2 prices, CCS, too, becomes profitable. If we were to rule out this technology for lowering CO2, much higher costs for the aimed-at decarbonisation of power generation would have to be accepted.

総合討論「発電以外の原子力利用の課題と展望」

総合討論「発電以外の原子力利用の課題と展望」

A novel nuclear combined power and cooling system integrating high temperature gas-cooled reactor with ammonia–water cycle

A nuclear ammonia–water power and refrigeration cogeneration system (NAPR) has been proposed and analyzed in this paper. It consists of a closed high temperature gas-cooled reactor (HTGR) topping Brayton cycle and a modified ammonia water power/refrigeration combined bottoming cycle (APR). The HTGR is an inherently safe reactor, and thus could be stable, flexible and suitable for various energy supply situation, and its exhaust heat is fully recovered by the mixture of ammonia and water in the bottoming cycle. To reduce exergy losses and enhance outputs, the ammonia concentrations of the bottoming cycle working fluid are optimized in both power and refrigeration processes. With the HTGR of 200MW thermal capacity and 900°C/70bar reactor-core-outlet helium, the system achieves 88.8MW net electrical output and 9.27MW refrigeration capacity, and also attains an energy efficiency of 69.9% and exergy efficiency of 72.5%, which are higher by 5.3%-points and 2.6%-points as compared with the nuclear combined cycle (NCC, like a conventional gas/steam power-only combined cycle while the topping cycle is a closed HTGR Brayton cycle) with the same nuclear energy input. Compared with conventional separate power and refrigeration generation systems, the fossil fuel saving (based on CH4) and CO2 emission reduction of base-case NAPR could reach ∼9.66×104t/y and ∼26.6×104t/y, respectively. The system integration accomplishes the safe and high-efficiency utilization of nuclear energy by power and refrigeration cogeneration.

Analysis of the Safety of Nuclear Power Plants

Nuclear energy is a carbon-free, clean and efficient energy. It is very important in the progress of human civilization and modern development of the world, however, there are still some problems such as nuclear leak and nuclear waste. In this paper, the worlds nuclear energy utilization and nuclear power plant constructions are reviewed and plans are forecasted. The basic reason of previous nuclear power plant accidents in history is summarized. Taking 2011 Tohuku earthquake-fukushima nuclear power station accident as an example,threats to the nuclear power plant by earthquake are investigated and impacts on social, economic and ecological environment caused by nuclear power station accident are analyzed. This paper drew lessons from previous accidents and put forward a variety of countermeasures which are from both the technical and management aspects. We also appeal people all over the world to respect the nature, enjoy the nature, and to create and enjoy the new civilization of human beings.

German Spent Nuclear Fuel Legacy: Characteristics and High-Level Waste Management Issues

Germany is phasing-out the utilization of nuclear energy until 2022. Currently, nine light water reactors of originally nineteen are still connected to the grid. All power plants generate high-level nuclear waste like spent uranium or mixed uranium-plutonium dioxide fuel which has to be properly managed. Moreover, vitrified high-level waste containing minor actinides, fission products, and traces of plutonium reprocessing loses produced by reprocessing facilities has to be disposed of. In the paper, the assessments of German spent fuel legacy (heavy metal content) and the nuclide composition of this inventory have been done. The methodology used applies advanced nuclear fuel cycle simulation techniques in order to reproduce the operation of the German nuclear power plants from 1969 till 2022. NFCSim code developed by LANL was adopted for this purpose. It was estimated that ~10,300 tonnes of unreprocessed nuclear spent fuel will be generated until the shut-down of the ultimate German reactor. This inventory will contain ~131 tonnes of plutonium, ~21 tonnes of minor actinides, and 440 tonnes of fission products. Apart from this, ca.215 tonnes of vitrified HLW will be present. As fission products and transuranium elements remain radioactive from 104to 106years, the characteristics of spent fuel legacy over this period are estimated, and their impacts on decay storage and final repository are discussed.

Fukushima and the Future of Radiation Research

There are now a good deal of data, opinions and speculation regarding the multiple disaster incident in Japan that began March 11, 2011 (1–7). Worldwide attention has focused on the risks, benefits and consequences of potential exposure to and uses for radiation. This article presents personal observations from participation in the response to this incident and projections as to how this major radiological incident might impact the future of the Radiation Research Society, and the important positive contributions radiation sciences can make to society in general. This watershed incident has and will continue to have a profound impact on nuclear energy utilization and cancer care, and demonstrates the importance of sound scientific underpinnings for decisions regarding uses and risks of radiation. This paper emphasizes the societal benefit from broad based radiation research. This perspective on future directions for radiation research and biomedical research in general is that of a physician-scientist, radiation/medical oncologist in academia (Stanford 1975–1985 and Harvard 1985–1999) and government [National Cancer Institute (NCI) since 1999 and also Office of the Assistant Secretary for Preparedness and Response (ASPR) since 2004]. The perspective of the Fukushima experience is from 8 years as a subject matter expert within the all-hazard planning team at ASPR, including a 3-week deployment in the U.S. Embassy in Tokyo during the crisis. My opinion of the spectrum of opportunities for the Radiation Research Society are from: (a) having been active in outreach to the medically underserved both locally and internationally since I graduated from Yale Medical School including the New Haven riots of the late 1960s, (b) working with the National Coalition for Cancer Survivorship since the early 1990s (8), (c) having seen the enormous change in health care and in federally supported research programs over periods of substantial growth over the 1980s and 1990s, and (d) experiencing as a laboratory researcher and as an NCI program leader regarding the pushback against rising health care costs and the effects of flat investment in biomedical research that has been front-and-center for the last 10 years. Since this is a personal perspective and not a review paper, only a limited number of representative references from the literature are provided. Two quotations attributable to Yogi Berra, the former New York Yankee catcher (9) were used to frame this presentation at the 2012 Radiation Research Society meeting that are as true as they are humorous:

The prospect of gas cooled fast reactors for long life reactors with natural uranium as fuel cycle input

Gas cooled fast reactors are among the Generation 4 nuclear power plants (NPPs) with hard neutron spectrum characteristics which can be utilized to create power reactors with high breeding/conversion ratio capability. In this study the gas cooled reactor system is combined with modified CANDLE burn-up scheme to create long life fast reactors with natural uranium as fuel cycle input. Such a system can utilize natural uranium resources efficiently without the necessity of enrichment plant or reprocessing plant. Therefore, by using this type of nuclear power plants optimum nuclear energy utilization, including in developing countries, can be easily obtained without the problem of nuclear proliferation. In this paper, a design study of 800MWt long-life gas cooled fast reactors with natural uranium as fuel cycle input has been performed. Due to the thermal hydraulic constraints, the average power density of the proposed design is limited to 70W/cc. The system has excellent performance and is at least comparable to that of Pb–Bi cooled system. The average discharge burn-up is about 258GWd/ton HM.

Optimization of Small Long Life Gas Cooled Fast Reactors with Natural Uranium as Fuel Cycle Input

In this study gas cooled reactor system are combined with modified CANDLE burn-up scheme to create small long life fast reactors with natural circulation as fuel cycle input. Such system can utilize natural Uranium resources efficiently without the necessity of enrichment plant or reprocessing plant. Therefore using this type of nuclear power plants optimum nuclear energy utilization including in developing countries can be easily conducted without the problem of nuclear proliferation. In this paper, optimization of Small and Medium Long-life Gas Cooled Fast Reactors with Natural Uranium as Fuel Cycle Input has been performed. The optimization processes include adjustment of fuel region movement scheme, volume fraction adjustment, core dimension, etc. Due to the limitation of thermal hydraulic aspects, the average power density of the proposed design is selected about 75 W/cc. With such condition we investigated small and medium sized cores from 300 MWt to 600 MWt with all being operated for 10 years without refueling and fuel shuffling and just need natural Uranium as fuel cycle input. The average discharge burn-up is about in the range of 23-30% HM.

Optimized Design and Discussion on Middle and Large CANDLE Reactors

CANDLE (Constant Axial shape of Neutron flux, nuclide number densities and power shape During Life of Energy producing reactor) reactors have been intensively researched in the last decades [1–6]. Research shows that this kind of reactor is highly economical, safe and efficiently saves resources, thus extending large scale fission nuclear energy utilization for thousands of years, benefitting the whole of society. For many developing countries with a large population and high energy demands, such as China and India, middle (1000 MWth) and large (2000 MWth) CANDLE fast reactors are obviously more suitable than small reactors [2]. In this paper, the middle and large CANDLE reactors are investigated with U-Pu and combined ThU-UPu fuel cycles, aiming to utilize the abundant thorium resources and optimize the radial power distribution. To achieve these design purposes, the present designs were utilized, simply dividing the core into two fuel regions in the radial direction. The less active fuel, such as thorium or natural uranium, was loaded in the inner core region and the fuel with low-level enrichment, e.g. 2.0% enriched uranium, was loaded in the outer core region. By this simple core configuration and fuel setting, rather than using a complicated method, we can obtain the desired middle and large CANDLE fast cores with reasonable core geometry and thermal hydraulic parameters that perform safely and economically; as is to be expected from CANDLE. To assist in understanding the CANDLE reactor’s attributes, analysis and discussion of the calculation results achieved are provided.