The nuclear event risk(NER)is an important and disputed factor that should be reasonably considered when planning the pathway of nuclear power development(NPD)to assess the benefits and risks of developing nuclear pow...The nuclear event risk(NER)is an important and disputed factor that should be reasonably considered when planning the pathway of nuclear power development(NPD)to assess the benefits and risks of developing nuclear power more objectively.This paper aims to explore the impact of nuclear events on NPD pathway planning.The influence of nuclear events is quantified as a monetary risk component,and an optimization model that incorporates the NER in the objective function is proposed.To optimize the pathway of NPD in the lowcarbon transition course of power supply structure evolution,a simulation model is built to deduce alternative NPD pathways and corresponding power supply evolution scenarios under the constraint of an exogenously assigned carbon emission pathway(CEP);moreover,a method is proposed to describe the CEP by superimposing the maximum carbon emission space and each carbon emission reduction(CER)component,and various CER components are clustered considering the emission reduction characteristics and resource endowments of different power generation technologies.A case study is conducted to explore the impact of NER and its risk valuation uncertainty on NPD pathway planning.The method presented in this paper allows the impact of nuclear events on NPD pathway planning to be quantified and improves the level of coordinated optimization of benefits and risks.展开更多
Ciliated protists are highly differentiated unicellular eukaryotes that possess special sexual processes(conjugation and autogamy)that rely on their unique nuclear dimorphism,i.e.,the presence of both a germline micro...Ciliated protists are highly differentiated unicellular eukaryotes that possess special sexual processes(conjugation and autogamy)that rely on their unique nuclear dimorphism,i.e.,the presence of both a germline micronucleus(MIC)and a somatic macronucleus(MAC)in a single cell.The sexual processes show a high diversity in different ciliates.To better understand the differentiation and evolution of sexual processes in closely related species,we investigated the nuclear events during conjugation in Paramecium jenningsi strain GZ,a poorly studied close relative of the well-known P.aurelia complex.The main results include:(1)the conjugation process takes about 48 h,including three prezygotic divisions(meiosis I,II,and mitosis)and three postzygotic divisions;(2)the MICs are dominated by the“parachute”phase at the prophase of meiosis I;(3)after meiosis II,a variable number of nuclei undergo the third prezygotic division,and the two products near the paroral cone become the genetically identical migratory and stationary pronuclei;(4)the synkaryon divides three times to form the MIC and the MAC anlagen,but only one nuclear product of the first postzygotic division completes the next two divisions;and(5)an extra cell division is required to complete the last step of conjugation,during which two MIC anlagen undergo mitotic division while two MAC anlagen are distributed between the daughter cells without division.The comparison of the nuclear events during conjugation in representatives of the class Oligohymenophorea reveals that usually there are three prezygotic divisions and a variable number of postzygotic divisions.However,the number of selected and differentiated nuclei after each division differs among species.This study provided a new model ciliate for further investigations of nuclear selection and differentiation as well as nuclear morphology during meiosis.展开更多
核电装备质量文本描述了核电装备在设计、采购、施工和调试阶段出现的质量缺陷等问题。由于不同阶段质量事件的发生频率不同,且同一装备对应不同阶段的质量文本中存在相同的关键词和相似的表述形式,针对类型数量不均衡和语义描述耦合的...核电装备质量文本描述了核电装备在设计、采购、施工和调试阶段出现的质量缺陷等问题。由于不同阶段质量事件的发生频率不同,且同一装备对应不同阶段的质量文本中存在相同的关键词和相似的表述形式,针对类型数量不均衡和语义描述耦合的质量文本分类问题,提出一种融合正则反馈焦点损失函数的改进循环池化网络分类模型。首先,采用BERT(Bidirectional Encoder Representation from Transformers)将核电装备质量文本转化为词向量;然后,提出一个改进的3层循环池化网络的分类模型结构,通过增加中间层并选择合适权重,扩大参数训练的提取空间,提升表征质量缺陷语义特征的能力;接着,提出正则反馈焦点损失函数来训练提出分类模型的参数,通过正则项使损失函数的梯度变化更稳定,根据反馈项对损失函数进行基于真实值和预测值之间误差的迭代调整,解决了不均衡样本在训练过程中梯度偏向不均衡的问题;最后,通过归一化指数函数计算出核电装备质量事件对应的阶段。在某核电公司真实数据集和公共数据集上,与Fast_Text网络相比,所提模型的F1值分别提高了2个百分点和1个百分点,实验结果表明该模型在文本分类任务中具有较高的准确性。展开更多
VVER-1200 (Water-Water Energetic Reactor) represents a significant advancement in nuclear power generation, emphasizing the continuous analysis and enhancement of safety systems for reliable operation. The proposed st...VVER-1200 (Water-Water Energetic Reactor) represents a significant advancement in nuclear power generation, emphasizing the continuous analysis and enhancement of safety systems for reliable operation. The proposed study focuses on simulating combined scenarios involving steam generator tube rupture (SGTR) and AC power loss using core algorithms and models within personal computer transient analyzer (PCTRAN). Reactor kinetic equations, thermal-hydraulic balance, and safety system models are discussed to elucidate their role in simulating SGTR and AC power loss. Safety criteria, boundaries and initial conditions are outlined to provide a comprehensive understanding of the simulation framework. The analysis delves into dynamic behavior of VVER-1200, placing emphasis on thermal-hydraulic implications, essential reactor parameters, and radiation monitoring to facilitate impact evaluation. Continuous monitoring and maintenance of safety systems are underscored to ensure stable core cooling, particularly during proposed transient conditions. Through meticulous analysis and comparison with established benchmarks, this study contributes to bolstering the safety and reliability of VVER-1200 reactors by identifying vulnerabilities, assessing mitigation strategies, and refining emergency response protocols. Practical implications of this study offer a crucial understanding of reactor behavior, safety system performance, and emergency response strategies, thereby improving safety, optimizing operational practices, and reducing risks in nuclear reactor accidents.展开更多
基金supported in part by the NARI Group Corporation Science and Technology project“Research on Coordinated Development of Carbon Emission Reduction and Carbon Sink Enhancement”。
文摘The nuclear event risk(NER)is an important and disputed factor that should be reasonably considered when planning the pathway of nuclear power development(NPD)to assess the benefits and risks of developing nuclear power more objectively.This paper aims to explore the impact of nuclear events on NPD pathway planning.The influence of nuclear events is quantified as a monetary risk component,and an optimization model that incorporates the NER in the objective function is proposed.To optimize the pathway of NPD in the lowcarbon transition course of power supply structure evolution,a simulation model is built to deduce alternative NPD pathways and corresponding power supply evolution scenarios under the constraint of an exogenously assigned carbon emission pathway(CEP);moreover,a method is proposed to describe the CEP by superimposing the maximum carbon emission space and each carbon emission reduction(CER)component,and various CER components are clustered considering the emission reduction characteristics and resource endowments of different power generation technologies.A case study is conducted to explore the impact of NER and its risk valuation uncertainty on NPD pathway planning.The method presented in this paper allows the impact of nuclear events on NPD pathway planning to be quantified and improves the level of coordinated optimization of benefits and risks.
基金supported by the National Natural Science Foundation of China(No.32270539,31961123002)the Natural Science Foundation of Shandong Province(ZR2020JQ13)+1 种基金the Fundamental Research Funds for the Central Universities(202141004)the Researchers Supporting Project Number(RSP2023R10)King Saud University,Riyadh,Saudi Arabia.
文摘Ciliated protists are highly differentiated unicellular eukaryotes that possess special sexual processes(conjugation and autogamy)that rely on their unique nuclear dimorphism,i.e.,the presence of both a germline micronucleus(MIC)and a somatic macronucleus(MAC)in a single cell.The sexual processes show a high diversity in different ciliates.To better understand the differentiation and evolution of sexual processes in closely related species,we investigated the nuclear events during conjugation in Paramecium jenningsi strain GZ,a poorly studied close relative of the well-known P.aurelia complex.The main results include:(1)the conjugation process takes about 48 h,including three prezygotic divisions(meiosis I,II,and mitosis)and three postzygotic divisions;(2)the MICs are dominated by the“parachute”phase at the prophase of meiosis I;(3)after meiosis II,a variable number of nuclei undergo the third prezygotic division,and the two products near the paroral cone become the genetically identical migratory and stationary pronuclei;(4)the synkaryon divides three times to form the MIC and the MAC anlagen,but only one nuclear product of the first postzygotic division completes the next two divisions;and(5)an extra cell division is required to complete the last step of conjugation,during which two MIC anlagen undergo mitotic division while two MAC anlagen are distributed between the daughter cells without division.The comparison of the nuclear events during conjugation in representatives of the class Oligohymenophorea reveals that usually there are three prezygotic divisions and a variable number of postzygotic divisions.However,the number of selected and differentiated nuclei after each division differs among species.This study provided a new model ciliate for further investigations of nuclear selection and differentiation as well as nuclear morphology during meiosis.
文摘核电装备质量文本描述了核电装备在设计、采购、施工和调试阶段出现的质量缺陷等问题。由于不同阶段质量事件的发生频率不同,且同一装备对应不同阶段的质量文本中存在相同的关键词和相似的表述形式,针对类型数量不均衡和语义描述耦合的质量文本分类问题,提出一种融合正则反馈焦点损失函数的改进循环池化网络分类模型。首先,采用BERT(Bidirectional Encoder Representation from Transformers)将核电装备质量文本转化为词向量;然后,提出一个改进的3层循环池化网络的分类模型结构,通过增加中间层并选择合适权重,扩大参数训练的提取空间,提升表征质量缺陷语义特征的能力;接着,提出正则反馈焦点损失函数来训练提出分类模型的参数,通过正则项使损失函数的梯度变化更稳定,根据反馈项对损失函数进行基于真实值和预测值之间误差的迭代调整,解决了不均衡样本在训练过程中梯度偏向不均衡的问题;最后,通过归一化指数函数计算出核电装备质量事件对应的阶段。在某核电公司真实数据集和公共数据集上,与Fast_Text网络相比,所提模型的F1值分别提高了2个百分点和1个百分点,实验结果表明该模型在文本分类任务中具有较高的准确性。
文摘VVER-1200 (Water-Water Energetic Reactor) represents a significant advancement in nuclear power generation, emphasizing the continuous analysis and enhancement of safety systems for reliable operation. The proposed study focuses on simulating combined scenarios involving steam generator tube rupture (SGTR) and AC power loss using core algorithms and models within personal computer transient analyzer (PCTRAN). Reactor kinetic equations, thermal-hydraulic balance, and safety system models are discussed to elucidate their role in simulating SGTR and AC power loss. Safety criteria, boundaries and initial conditions are outlined to provide a comprehensive understanding of the simulation framework. The analysis delves into dynamic behavior of VVER-1200, placing emphasis on thermal-hydraulic implications, essential reactor parameters, and radiation monitoring to facilitate impact evaluation. Continuous monitoring and maintenance of safety systems are underscored to ensure stable core cooling, particularly during proposed transient conditions. Through meticulous analysis and comparison with established benchmarks, this study contributes to bolstering the safety and reliability of VVER-1200 reactors by identifying vulnerabilities, assessing mitigation strategies, and refining emergency response protocols. Practical implications of this study offer a crucial understanding of reactor behavior, safety system performance, and emergency response strategies, thereby improving safety, optimizing operational practices, and reducing risks in nuclear reactor accidents.
