Considering the growing global demand for energy and the need for countries to achieve climate goals,there is an increasing global interest in small modular reactors(SMRs)and their applications.Accident source term an...Considering the growing global demand for energy and the need for countries to achieve climate goals,there is an increasing global interest in small modular reactors(SMRs)and their applications.Accident source term and radiological consequence evaluations of SMRs are key components of nuclear and radiation safety reviews,which affect the site,exclusion area(EAB),and low population zone outer boundaries.Based on the design characteristics of the SMR and accident analysis results,a theoretical model of a whole-core fuel cladding damage accident was constructed to study the radioactivity released into the environment and its consequences.The accident source term and radiation dose calculation models were established to analyze the released amounts of radionuclides and the total effective dose affecting individuals at the site boundary.The results showed that the amount of radionuclides released into the environment after a whole-core fuel cladding damage accident reached 10^(14) Bq,among which the release amount of ^(133)Xe was the largest.The total effective dose at the site boundary 30 days after the accident was 8.65 mSv.The highest total effective dose affecting individuals occurred to the east-north-east.The results of the accident source term and radiological consequence provide technical support for site boundary dose assessments and reviews of SMRs.展开更多
The fast growth in the size and difficulty of nuclear power plant in the 1970s produced an interest in smaller, modest designs that are intrinsically safe over the usage of design features. With the development of nuc...The fast growth in the size and difficulty of nuclear power plant in the 1970s produced an interest in smaller, modest designs that are intrinsically safe over the usage of design features. With the development of nuclear technology, there is the need for revolution in the Maritime sector, especially the advance marine propulsion. In current years, numerous reactor manufacturers are dynamically improving small modular reactor designs with even superior use of safety features. Several designs integrate the ultimate in greater safety. They totally remove specific accident initiators from the design. Other design features benefit to reduce different types of accident or help to mitigate the accident’s consequences. Although some safety features are mutual to maximum SMR designs, irrespective of the coolant technology, other features are specific to liquid-metal cooled, water, gas, or SMR designs. Results: There have been more reactor concepts investigated in the marine propulsion area by different assemblies and research laboratories than in the power generation field, and much can be learned from their experience for land applications. The extensive use of safety features in SMRs potential to make these power plants extremely vigorous, protecting both the public and the investor. Conclusion: For these two considerations, it is recognized that a nuclear reactor is the ideal engine for naval advanced propulsion. The paper will present the work to analyze the concept design of SMRs and design a modular vessel consisting of a propulsion module.展开更多
The United Arab Emirates lacks conventional water resources and relies primarily on desalination plants powered by fossil fuels to produce fresh water.Nuclear desalination is a proven technology,cost-competitive,and s...The United Arab Emirates lacks conventional water resources and relies primarily on desalination plants powered by fossil fuels to produce fresh water.Nuclear desalination is a proven technology,cost-competitive,and sustainable option capable of integrating the existing largescale desalination plants to produce both freshwater and electricity.However,Small Modular Reactors(SMRs)are promising designs with advanced simplified configurations and inherent safety features.In this study,an Integrated Desalination SMR that produces thermal energy compatible with the capacity of a fossil fuel-powered desalination plant in the UAE was designed.First,the APR-1400 reactor core was used to investigate two 150 MWthconceptual SMR core designs,core A and core B,based on two-dimensional parameters,radius,and height.Then,the CASMO-4 lattice code was used to generate homogenized few-group constants for optimized fuel assembly loading patterns.Finally,to find the best core configuration,SIMULATE-3 was used to calculate the core key physics parameters such as power distribution,reactivity coefficients,and critical boron concentration.In addition,different reflector materials were investigated to compensate for the expected high leakage of the small-sized SMR cores.The pan shape core B model(142.6132 cm diameter,100 cm height,and radially reflected by Stainless Steel)was selected as the best core configuration based on its calculated physics parameters.Core B met the design and safety criteria and indicated low total neutron leakage of 11.60%and flat power distribution with 1.50 power peaking factor.Compared to core A,it has a more negative MTC value of-6.93 pcm/°F with lower CBC.In a 2-batch scheme,the fuel is discharged at 42.25 GWd/MTU burnup after a long cycle length of 1.58 years.The core B model offers the highest specific power of 36.56 kW/kgU while utilizing the smallest heavy metal mass compared with the SMART and NuScale models.展开更多
Small modular reactors (SMRs) offer simple, standardized, and safe modular designs for new nuclear reactor construction. They are factory built, requiring smaller initial capital investment and facilitating shorter co...Small modular reactors (SMRs) offer simple, standardized, and safe modular designs for new nuclear reactor construction. They are factory built, requiring smaller initial capital investment and facilitating shorter construction times. SMRs also promise competitive economy when compared with the current reactor fleet. Construction cost of a majority of the projects, which are mostly in their design stages, is not publicly available, but variable costs can be determined from fuel enrichment, average burn-up, and plant thermal efficiency, which are public parameters for many near-term SMR projects. The fuel cost of electricity generation for selected SMRs and large reactors is simulated, including calculation of optimal tails assay in the uranium enrichment process. The results are compared between one another and with current generation large reactor designs providing a rough comparison of the long-term economics of a new nuclear reactor project. SMRs are predicted to have higher fuel costs than large reactors. Particularly, integral pressurized water reactors (iPWRs) are shown to have from 15% to 70% higher fuel costs than large light water reactors using 2014 nuclear fuels market data. Fuel cost sensitivities to reactor design parameters are presented.展开更多
In recent years,various types of surrogate optimization models have been proposed to reduce the computational time and to improve the emulation accuracy.In this study,by leveraging an ANN surrogate model developed ear...In recent years,various types of surrogate optimization models have been proposed to reduce the computational time and to improve the emulation accuracy.In this study,by leveraging an ANN surrogate model developed earlier,a comprehensive and efficient optimization algorithm is conceived for the global optimal design of an integrated regenerative methanol transcritical cycle.It combines a unique converging/diverging classifier model into the surrogate model to form a surrogate-based model,which significantly improves the prediction accuracy of the objective function.Six binary classifiers are explored and the multi-layer feed-forward(MLF)neural network classifier is selected.In addition,within the five global optimizers being explored,the basinhopping(BH)and dual-annealing(DA)are selected.The optimal surrogate-based model and global optimizers are then combined to form a unique surrogate-optimizer model.The surrogate-optimizer model is slightly outperformed by the physics-based model in terms of the optimization results,the time consumption of the surrogate-optimizer model during the optimization searching process is 99%less than that of the physicsbased model.As the results,the surrogate-optimizer model is slightly outperformed by the physics-based model in terms of the optimization results,where the Levelized Cost of Energy(LCOE)of the Surrogate-DA and Surrogate-BH models are 77.912 and 78.876$/MWh,respectively,compared to the 77.190$/MWh of the Baseline model with fairly close penalties between them.In the meantime,the time consumption of the surrogate-optimizer model during the optimization searching process is 99%less than that of the physics-based model.展开更多
Small long-life transportable high temperature gas-cooled reactors(HTRs) are interesting because they can safely provide electricity or heat in remote areas or to industrial users in developed or developing countries....Small long-life transportable high temperature gas-cooled reactors(HTRs) are interesting because they can safely provide electricity or heat in remote areas or to industrial users in developed or developing countries.This paper presents the neutronic design of the U-Battery,which is a 5 MWth block-type HTR with a fuel lifetime of 5–10 years.Assuming a reactor pressure vessel diameter of less than 3.7 m,some possible reactor core configurations of the 5 MWth U-Battery have been investigated using the TRITON module in SCALE 6.The neutronic analysis shows that Layout 12×2B,a scattering core containing 2 layers of 12 fuel blocks each with 20% enriched235U,reaches a fuel lifetime of 10 effective full power years(EFPYs).When the diameter of the reactor pressure vessel is reduced to 1.8 m,a fuel lifetime of 4 EFPYs will be achieved for the 5 MWth U-Battery with a 25-cm thick graphite side reflector.Layouts 6×3 and 6×4 with a 25-cm thick BeO side reflector achieve a fuel lifetime of 7 and 10 EFPYs,respectively.The comparison of the different core configurations shows that,keeping the number of fuel blocks in the reactor core constant,the annular and scattering core configurations have longer fuel lifetimes and lower fuel cost than the cylindrical ones.Moreover,for the 5 MWth U-Battery,reducing the fuel inventory in the reactor core by decreasing the diameter of fuel kernels and packing fraction of TRISO particles is more effective to lower the fuel cost than decreasing the 235U enrichment.展开更多
The WRNM(wide range neutron monitoring)is a newly developed neutron monitoring channel which was initially conceived as a means to meet Regulatory Guide 1.97 requirements for post-accident neutron monitoring.The scope...The WRNM(wide range neutron monitoring)is a newly developed neutron monitoring channel which was initially conceived as a means to meet Regulatory Guide 1.97 requirements for post-accident neutron monitoring.The scope was expanded to include the startup monitoring function with the aim of replacing both the source and IRMs(intermediate range monitors)in BWRs(boiling water reactors).The WRNMs,consisting of a newly designed fixed incore regenerative sensor and new electronics,which include both counting and MSV(mean square voltage)channels,have been tested in several reactors and its capabilities have been confirmed.The channel will cover the neutron flux range from 103 nv to 1.5×103 nv;it has greater than 1 decade overlap between the counting and MSV channels.Because of the regenerative fissile coating the sensor,even though fixed incore,has a life of approximately 6.0 full power years in a 51 kW/L BWR and similar situation has been proposed for newly designed small modular reactor such as BWRX-300 of General Electric Hitachi reactor.展开更多
文摘Considering the growing global demand for energy and the need for countries to achieve climate goals,there is an increasing global interest in small modular reactors(SMRs)and their applications.Accident source term and radiological consequence evaluations of SMRs are key components of nuclear and radiation safety reviews,which affect the site,exclusion area(EAB),and low population zone outer boundaries.Based on the design characteristics of the SMR and accident analysis results,a theoretical model of a whole-core fuel cladding damage accident was constructed to study the radioactivity released into the environment and its consequences.The accident source term and radiation dose calculation models were established to analyze the released amounts of radionuclides and the total effective dose affecting individuals at the site boundary.The results showed that the amount of radionuclides released into the environment after a whole-core fuel cladding damage accident reached 10^(14) Bq,among which the release amount of ^(133)Xe was the largest.The total effective dose at the site boundary 30 days after the accident was 8.65 mSv.The highest total effective dose affecting individuals occurred to the east-north-east.The results of the accident source term and radiological consequence provide technical support for site boundary dose assessments and reviews of SMRs.
文摘The fast growth in the size and difficulty of nuclear power plant in the 1970s produced an interest in smaller, modest designs that are intrinsically safe over the usage of design features. With the development of nuclear technology, there is the need for revolution in the Maritime sector, especially the advance marine propulsion. In current years, numerous reactor manufacturers are dynamically improving small modular reactor designs with even superior use of safety features. Several designs integrate the ultimate in greater safety. They totally remove specific accident initiators from the design. Other design features benefit to reduce different types of accident or help to mitigate the accident’s consequences. Although some safety features are mutual to maximum SMR designs, irrespective of the coolant technology, other features are specific to liquid-metal cooled, water, gas, or SMR designs. Results: There have been more reactor concepts investigated in the marine propulsion area by different assemblies and research laboratories than in the power generation field, and much can be learned from their experience for land applications. The extensive use of safety features in SMRs potential to make these power plants extremely vigorous, protecting both the public and the investor. Conclusion: For these two considerations, it is recognized that a nuclear reactor is the ideal engine for naval advanced propulsion. The paper will present the work to analyze the concept design of SMRs and design a modular vessel consisting of a propulsion module.
基金supported by the Office of Vice Chancellor for Research&Graduate Studies,University of Sharjah,under grant no. V.C.R.G./R.1325/2021
文摘The United Arab Emirates lacks conventional water resources and relies primarily on desalination plants powered by fossil fuels to produce fresh water.Nuclear desalination is a proven technology,cost-competitive,and sustainable option capable of integrating the existing largescale desalination plants to produce both freshwater and electricity.However,Small Modular Reactors(SMRs)are promising designs with advanced simplified configurations and inherent safety features.In this study,an Integrated Desalination SMR that produces thermal energy compatible with the capacity of a fossil fuel-powered desalination plant in the UAE was designed.First,the APR-1400 reactor core was used to investigate two 150 MWthconceptual SMR core designs,core A and core B,based on two-dimensional parameters,radius,and height.Then,the CASMO-4 lattice code was used to generate homogenized few-group constants for optimized fuel assembly loading patterns.Finally,to find the best core configuration,SIMULATE-3 was used to calculate the core key physics parameters such as power distribution,reactivity coefficients,and critical boron concentration.In addition,different reflector materials were investigated to compensate for the expected high leakage of the small-sized SMR cores.The pan shape core B model(142.6132 cm diameter,100 cm height,and radially reflected by Stainless Steel)was selected as the best core configuration based on its calculated physics parameters.Core B met the design and safety criteria and indicated low total neutron leakage of 11.60%and flat power distribution with 1.50 power peaking factor.Compared to core A,it has a more negative MTC value of-6.93 pcm/°F with lower CBC.In a 2-batch scheme,the fuel is discharged at 42.25 GWd/MTU burnup after a long cycle length of 1.58 years.The core B model offers the highest specific power of 36.56 kW/kgU while utilizing the smallest heavy metal mass compared with the SMART and NuScale models.
文摘Small modular reactors (SMRs) offer simple, standardized, and safe modular designs for new nuclear reactor construction. They are factory built, requiring smaller initial capital investment and facilitating shorter construction times. SMRs also promise competitive economy when compared with the current reactor fleet. Construction cost of a majority of the projects, which are mostly in their design stages, is not publicly available, but variable costs can be determined from fuel enrichment, average burn-up, and plant thermal efficiency, which are public parameters for many near-term SMR projects. The fuel cost of electricity generation for selected SMRs and large reactors is simulated, including calculation of optimal tails assay in the uranium enrichment process. The results are compared between one another and with current generation large reactor designs providing a rough comparison of the long-term economics of a new nuclear reactor project. SMRs are predicted to have higher fuel costs than large reactors. Particularly, integral pressurized water reactors (iPWRs) are shown to have from 15% to 70% higher fuel costs than large light water reactors using 2014 nuclear fuels market data. Fuel cost sensitivities to reactor design parameters are presented.
基金financial support provided for the study,and Nuclear Regulatory Commission(NRC)for its financial support through the Award No.31310019M0014.
文摘In recent years,various types of surrogate optimization models have been proposed to reduce the computational time and to improve the emulation accuracy.In this study,by leveraging an ANN surrogate model developed earlier,a comprehensive and efficient optimization algorithm is conceived for the global optimal design of an integrated regenerative methanol transcritical cycle.It combines a unique converging/diverging classifier model into the surrogate model to form a surrogate-based model,which significantly improves the prediction accuracy of the objective function.Six binary classifiers are explored and the multi-layer feed-forward(MLF)neural network classifier is selected.In addition,within the five global optimizers being explored,the basinhopping(BH)and dual-annealing(DA)are selected.The optimal surrogate-based model and global optimizers are then combined to form a unique surrogate-optimizer model.The surrogate-optimizer model is slightly outperformed by the physics-based model in terms of the optimization results,the time consumption of the surrogate-optimizer model during the optimization searching process is 99%less than that of the physicsbased model.As the results,the surrogate-optimizer model is slightly outperformed by the physics-based model in terms of the optimization results,where the Levelized Cost of Energy(LCOE)of the Surrogate-DA and Surrogate-BH models are 77.912 and 78.876$/MWh,respectively,compared to the 77.190$/MWh of the Baseline model with fairly close penalties between them.In the meantime,the time consumption of the surrogate-optimizer model during the optimization searching process is 99%less than that of the physics-based model.
文摘Small long-life transportable high temperature gas-cooled reactors(HTRs) are interesting because they can safely provide electricity or heat in remote areas or to industrial users in developed or developing countries.This paper presents the neutronic design of the U-Battery,which is a 5 MWth block-type HTR with a fuel lifetime of 5–10 years.Assuming a reactor pressure vessel diameter of less than 3.7 m,some possible reactor core configurations of the 5 MWth U-Battery have been investigated using the TRITON module in SCALE 6.The neutronic analysis shows that Layout 12×2B,a scattering core containing 2 layers of 12 fuel blocks each with 20% enriched235U,reaches a fuel lifetime of 10 effective full power years(EFPYs).When the diameter of the reactor pressure vessel is reduced to 1.8 m,a fuel lifetime of 4 EFPYs will be achieved for the 5 MWth U-Battery with a 25-cm thick graphite side reflector.Layouts 6×3 and 6×4 with a 25-cm thick BeO side reflector achieve a fuel lifetime of 7 and 10 EFPYs,respectively.The comparison of the different core configurations shows that,keeping the number of fuel blocks in the reactor core constant,the annular and scattering core configurations have longer fuel lifetimes and lower fuel cost than the cylindrical ones.Moreover,for the 5 MWth U-Battery,reducing the fuel inventory in the reactor core by decreasing the diameter of fuel kernels and packing fraction of TRISO particles is more effective to lower the fuel cost than decreasing the 235U enrichment.
文摘The WRNM(wide range neutron monitoring)is a newly developed neutron monitoring channel which was initially conceived as a means to meet Regulatory Guide 1.97 requirements for post-accident neutron monitoring.The scope was expanded to include the startup monitoring function with the aim of replacing both the source and IRMs(intermediate range monitors)in BWRs(boiling water reactors).The WRNMs,consisting of a newly designed fixed incore regenerative sensor and new electronics,which include both counting and MSV(mean square voltage)channels,have been tested in several reactors and its capabilities have been confirmed.The channel will cover the neutron flux range from 103 nv to 1.5×103 nv;it has greater than 1 decade overlap between the counting and MSV channels.Because of the regenerative fissile coating the sensor,even though fixed incore,has a life of approximately 6.0 full power years in a 51 kW/L BWR and similar situation has been proposed for newly designed small modular reactor such as BWRX-300 of General Electric Hitachi reactor.
文摘先进的小型模块化反应堆(简称小堆)设计广泛地采用一体化结构设计与非能动安全理念,使小堆固有安全性显著提升.然而,在实现小堆广泛商用化之前,需要对其安全性进行全面评估.该研究利用严重事故分析程序MELCOR,对WSMR(Westinghouse small modular reactor)进行建模,以全厂断电事故为基础事故序列,分析了全厂断电事故在WSMR中的事故进程;同时对非能动安全系统在全厂断电事故下的缓解能力进行了研究,其中着重探讨堆芯补水箱的事故缓解作用,并针对堆芯补水箱的有效运行数量与启用时间进行了敏感性分析.研究结果表明:全厂断电事故会导致堆芯冷却能力下降,从而造成堆芯坍塌失效;而堆芯补水箱能够为反应堆提供额外的冷却剂,且利用余热移除热交换器将堆芯余热移至外部最终热阱水箱中,从而保证堆芯的长期冷却.相关敏感性分析结果表明:在其他非能动安全设施全部失效的情况下,至少需要2个正常运行的堆芯补水箱才能有效缓解事故;在堆芯补水箱启动失败的情况下,若考虑重新启用堆芯补水箱,重启时间应不晚于52.5 ks才能避免堆芯结构损坏.该研究结果可为相关小堆的严重事故管理导则的制定和改进提供参考,从而增强对全厂断电事故的应对能力,同时有利于提升模块化小堆非能动安全系统的事故缓解能力.
