Study on the influence of flow blockage in severe accident scenario of CAP1400 reactor

Gao Pengcheng,Zhang Bin,Li Jishen,Miao Fan,Tang Shaowei,Cao Sheng,Yang Hao,Shan Jianqiang 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

Deformed fuel rods can cause a partial blockage of the flow area in a subchannel. Such flow blockage will influence the core coolant flow and further the core heat transfer during the reflooding phase and subsequent severe accidents. Nevertheless, most of the system analysis codes simulate the accident process based on the assumed flow blockage ratio, resulting in inconsistencies between simulated results and actual conditions. This paper aims to study the influence of flow blockage in severe accident scenario of the CAP1400 reactor. First, the flow blockage model of ISAA code is improved based on the FRTMB module. Then, the ISAA-FRTMB coupling system is adopted to model and calculate the QUENCH-LOCA- 0 experiment. The correctness and validity of the flow blockage model are verified by comparing the peak cladding temperature. Finally, the DVI Line-SBLOCA accident is induced to analyze the influence of flow blockage on subsequent CAP1400 reactor core heat transfer and core degradation. From the results of the DVI Line-SBLOCA accident analysis, it can be concluded that the blockage ratio is in the range of 40%e60%, and the position of severe blockage is the same as that of cladding rupture. The blockage reduces the circulation area of the core coolant, which in turn impacts the heat exchange between the core and the coolant, leading to the early failure and collapse of some core assemblies and accelerating the core degradation process.

Development of mechanistic cladding rupture model for severe accident analysis and application in PHEBUS FPT3 experiment

Pengcheng Gao,Bin Zhang,Jishen Li,Jianqiang Shan 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

Cladding ballooning and rupture are the important phenomena at the early stage of a severe accident. Most severe accident analysis codes determine the cladding rupture based on simple parameter models. In this paper, a FRTMB module was developed using the thermal-mechanical model to analyze the fuel mechanical behavior. The purpose is to judge the cladding rupture with the severe accident analysis code. The FRTMB module was integrated into the self-developed severe accident analysis code ISAA to simulate the PHEBUS FPT3 experiment. The predicted rupture time and temperature of the cladding were basically consistent with the measured values, which verified the correctness and effectiveness of the FRTMB module. The results showed that the rising of gas pressure in the fuel rod and high temperature led to cladding ballooning. Consequently, the cladding hoop strain exceeded the strain limit, and the cladding burst. The developed FRTMB module can be applied not only to rod-type fuel, but also to plate-type fuel and other types of reactor fuel rods. Moreover, the FRTMB module can improve the channel blockage model of ISAA code and make contributions to analyzing the effect of clad ballooning on transient and subsequent parts of core degradation.

Study on the effect of flow blockage due to rod deformation in QUENCH experiment

Gao Pengcheng,Zhang Bin,Shan Jianqiang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

During a loss-of-coolant accident (LOCA) in the pressurized water reactor (PWR), there is a possibility that high temperature and internal pressure of the fuel rods lead to ballooning of the cladding, which causes a partial blockage of flow area in a subchannel. Such flow blockage would influence the core coolant flow, thus affecting the core heat transfer during a reflooding phase and subsequent severe accident. However, most of the system analysis codes simulate the accident process based on the assumed channel blockage ratio, resulting in the fact that the simulation results are not consistent with the actual situation. This paper integrates the developed core Fuel Rod Thermal-Mechanical Behavior analysis (FRTMB) module into the self-developed severe accident analysis code ISAA. At the same time, the existing flow blockage model is improved to make it possible to simulate the change of flow distribution due to fuel rod deformation. Finally, the ISAA-FRTMB is used to simulate the QUENCH-LOCA0 experiment to verify the correctness and effectiveness of the improved flow blockage model, and then the effect of clad ballooning on core heat transfer and subsequent parts of core degradation is analyzed.

The Brachypodium distachyon methionine sulfoxide reductase gene family

Yankun Gao,Jiantang Zhu,Pengcheng Ding,Guangmin Xia,Fanguo Chen 한국유전학회 2017 Genes & Genomics Vol.39 No.9

The methionine sulfoxide reductases (MSRs) are a group of thiol-dependent enzymes able to catalyze the conversion of methionine sulfoxide to methionine. Although some plant MSRs are known to act as protectants against various abiotic stresses, their activity in the model grass species Brachypodium distachyon has not been characterized as yet. Here, six B. distachyon MSR (BdMSR) genes have been isolated; they generate eight distinct cDNAs, since two of them (BdMSRB1 and -B5) produce a pair of alternatively spliced messages. The genes were transcribed in the root, culm, leaf and during various stages of caryopsis development. Those induced by abiotic stress (salinity, drought, low temperature, CdCl2, H2O2 and abscisic acid) harbored known stress-responsive cis elements in their promoter sequences. The heterologous expression of five of the BdMSRs (-A2, -A4, -B1.1, -B3 and -B5.1) in yeast revealed that their products gave a measure of protection against salinity, mannitol and oxidative stress. Substrate specificity analysis revealed that BdMSRB1.1 could reduce free Met-R-SO to Met. The enzymatic activities of BdMSRA4, -B1.1 and -B5.1 in transformed yeast under salt treatment have checked and increased obviously resulting in reducing more Met-SO to Met including the peptide and the free types under salt stress than those in control.

The natural product salicin alleviates osteoarthritis progression by binding to IRE1α and inhibiting endoplasmic reticulum stress through the IRE1α-IκBα-p65 signaling pathway

Zhu Zhenglin,Gao Shengqiang,Chen Cheng,Xu Wei,Xiao Pengcheng,Chen Zhiyu,Du Chengcheng,Chen Bowen,Gao Yan,Wang Chunli,Wang Chunli,Huang Wei 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Despite the high prevalence of osteoarthritis (OA) in older populations, disease-modifying OA drugs (DMOADs) are still lacking. This study was performed to investigate the effects and mechanisms of the small molecular drug salicin (SA) on OA progression. Primary rat chondrocytes were stimulated with TNF-α and treated with or without SA. Inflammatory factors, cartilage matrix degeneration markers, and cell proliferation and apoptosis markers were detected at the mRNA and protein levels. Cell proliferation and apoptosis were evaluated by EdU assays or flow cytometric analysis. RNA sequencing, molecular docking and drug affinity-responsive target stability analyses were used to clarify the mechanisms. The rat OA model was used to evaluate the effect of intra-articular injection of SA on OA progression. We found that SA rescued TNF-α-induced degeneration of the cartilage matrix, inhibition of chondrocyte proliferation, and promotion of chondrocyte apoptosis. Mechanistically, SA directly binds to IRE1α and occupies the IRE1α phosphorylation site, preventing IRE1α phosphorylation and regulating IRE1α-mediated endoplasmic reticulum (ER) stress by IRE1α-IκBα-p65 signaling. Finally, intra-articular injection of SA-loaded lactic-co-glycolic acid (PLGA) ameliorated OA progression by inhibiting IRE1α-mediated ER stress in the OA model. In conclusion, SA alleviates OA by directly binding to the ER stress regulator IRE1α and inhibits IRE1α-mediated ER stress via IRE1α-IκBα-p65 signaling. Topical use of the small molecular drug SA shows potential to modify OA progression.

Performance evaluation of Accident Tolerant Fuel under station blackout accident in PWR nuclear power plant by improved ISAA code

Zhang Bin,Gao Pengcheng,Xu Tao,Gui Miao,Shan Jianqiang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.7

The Accident Tolerant Fuel (ATF) is a new concept of fuel, which can not only withstand the consequences of the accident for a longer time, but also maintain or improve the performance under operating conditions. ISAA is a self-developed severe accident analysis code, which uses modular structures to simulate the development processes of severe accidents in nuclear plants. The basic version of ISAA is developed based on UO2eZr fuel. To study the potential safety gain of ATF cladding, an improved version of ISAA, referred to as ISAA-ATF, is introduced to analyze the station blackout accident of PWR using ATF cladding. The results show that ATF cladding enable the core to maintain a longer time compared to zirconium alloy cladding, thereby enhancing the accident mitigation capability. Meanwhile, the generation of hydrogen is significantly reduced and delayed, which proves that ATF can improve the safety characteristics of the nuclear reactor.

EDMFEN: Edge detection-based multi-scale feature enhancement Network for low-light image enhancement

Canlin Li,Shun Song,Pengcheng Gao,Wei Huang,Lihua Bi 한국인터넷정보학회 2024 KSII Transactions on Internet and Information Syst Vol.18 No.4

To improve the brightness of images and reveal hidden information in dark areas is the main objective of low-light image enhancement (LLIE). LLIE methods based on deep learning show good performance. However, there are some limitations to these methods, such as the complex network model requires highly configurable environments, and deficient enhancement of edge details leads to blurring of the target content. Single-scale feature extraction results in the insufficient recovery of the hidden content of the enhanced images. This paper proposed an edge detection-based multi-scale feature enhancement network for LLIE (EDMFEN). To reduce the loss of edge details in the enhanced images, an edge extraction module consisting of a Sobel operator is introduced to obtain edge information by computing gradients of images. In addition, a multi-scale feature enhancement module (MSFEM) consisting of multi-scale feature extraction block (MSFEB) and a spatial attention mechanism is proposed to thoroughly recover the hidden content of the enhanced images and obtain richer features. Since the fused features may contain some useless information, the MSFEB is introduced so as to obtain the image features with different perceptual fields. To use the multi-scale features more effectively, a spatial attention mechanism module is used to retain the key features and improve the model performance after fusing multi-scale features. Experimental results on two datasets and five baseline datasets show that EDMFEN has good performance when compared with the state-of-the-art LLIE methods.

Sequence Pulse Modulation for Voltage Balance in a Cascaded H-Bridge Rectifier

Xu Peng,Xiaoqiong He,Pengcheng Han,Xiaolan Lin,Zeliang Shu,Shibin Gao 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3

With the development of multilevel converters, cascaded single-phase H-bridge rectifiers (CHBRs) has become widely adopted in high-voltage high-power applications. In this study, sequence pulse modulation (SPM) is proposed for CHBRs. SPM is designed to balance the dc-link voltage and maintain the smooth changes of switch states. In contrast to phase disposition modulation, SPM balances the dc-link voltage even after removing the load of one submodule. The operation principle of SPM is deduced, and the unbalance degree of SPM is analyzed. All the proposed approaches are experimentally verified through a prototype of a four-module (nine-level) CHBR. Conclusions are drawn in accordance with the results of SPM and its imbalance degree analysis.

Improvement and validation of aerosol models for natural deposition mechanism in reactor containment

Jishen Li,Bin Zhang,Pengcheng Gao,Fan Miao,Jianqiang Shan Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

Nuclear safety is the lifeline for the development and application of nuclear energy. In severe accidents of pressurized water reactor (PWR), aerosols, as the main carrier of fission products, are suspended in the containment vessel, posing a potential threat of radioactive contamination caused by leakage into the environment. The gas-phase aerosols suspended in the containment will settle onto the wall or sump water through the natural deposition mechanism, thereby reducing atmospheric radioactivity. Aiming at the low accuracy of the aerosol model in the ISAA code, this paper improves the natural deposition model of aerosol in the containment. The aerosol dynamic shape factor was introduced to correct the natural deposition rate of non-spherical aerosols. Moreover, the gravity, Brownian diffusion, thermophoresis and diffusiophoresis deposition models were improved. In addition, ABCOVE, AHMED and LACE experiments were selected to validate and evaluate the improved ISAA code. According to the calculation results, the improved model can more accurately simulate the peak aerosol mass and respond to the influence of the containment pressure and temperature on the natural deposition rate of aerosols. At the same time, it can significantly improve the calculation accuracy of the residual mass of aerosols in the containment. The performance of improved ISAA can meet the requirements for analyzing the natural deposition behavior of aerosol in containment of advanced PWRs in severe accident. In the future, further optimization will be made to address the problems found in the current aerosol model.

중국 상장기업의 사회적 책임에 관한 연구

김광록(Kwang Rok Kim),高?程(Gao Pengcheng) 한국기업법학회 2021 企業法硏究 Vol.35 No.1

기업의 사회적 책임은 1950년대에 이르러 미국에서 최초로 논의되기 시작하였으며, 최근에는 우리나라를 비롯해서 많은 국가들도 이를 회사법의 범주에 적극적으로 도입하고자 하는 추세이다. 이러한 추세는 최근 몇년간 급격한 경제 사회적 발전을 이룬 중국의 경우에도 마찬가지이다. 중국 국민의 사회의식도 지속적으로 성장하고 있으며, 기업의 경우에도 경제적인 측면에서 뿐만 아니라 사회 전반적인 측면에서 다양한 참여활동을 주도하는 경우도 많아지고 있다. 이러한 사정에서 최근 중국에서도 기업에 대한, 특히 상장기업에 대한 사회적 책임을 어떻게 정립할 것인가가 중요한 문제가 되고 있다. 물론 중국 기업의 사회적 책임에 대한 구체적인 구축 문제는 아직까지는 초보적인 수준에 머무르고 있는 것이 사실이다. 그러나 중국 정부도 이와 관련한 정책을 펴는 등 기업의 사회적 책임의식과 능력이 크게 향상되어 현재에는 기업의 사회적 책임 구축의 형식, 내용 및 범위에서 나름대로 발전하고 있다고 할 것이다. 그러나 동시에 이는 기업간 불균형, 형식주의, 내생동력 부족, 감독규제 미비 등의 문제로 크게 진전을 이루지는 못하고 있는 실정이다. 따라서 이 글은 특히 중국의 상해 증권거래소 및 심천 증권거래소에 상장된 상장기업을 대상으로 중국 상장기업의 기업의 사회적책임 문제를 연구 및 분석함으로써 향후 중국 상장기업의 사회적 책임의 구체적인 정립 방향을 제시하는 데 도움을 주고자 하였다. In recent years, China’s economic and social construction has made great progress, and the awareness of civil society is also constantly improving. In addition to their own economic construction, enterprises are participating in social construction more and more. The most important of the social construction is corporate social responsibility construction. China’s corporate social responsibility construction is still in the preliminary development stage. The government has also issued relevant policy guidance and enterprise’s corporate social responsibility awareness and capabilities have also been greatly improved. The form, content and scope of corporate social responsibility construction have made significant progress, but at the same time, China’s corporate social responsibility construction is also facing problems such as unbalanced development, formalism, insufficient endogenous motivation, imperfect supervision, etc. This article focuses on China’s listed companies on the Shanghai and Shenzhen stock markets to explore and analyze issues of China’s listed companies’ corporate social responsibility construction in order to help the current corporate social responsibility construction.