Chinese Nuclear Power Plant Research Articles

Plutonium in the coastal seawater around Chinese nuclear power plants: Sources, distribution, and environmental implications

Coastal surface seawater samples within 30 km around ten Chinese nuclear power plants (NPPs) were systematically investigated. The 239+240Pu activity concentration in the samples varied from 0.226 mBq/m3 to 3.098 mBq/m3, meanwhile the 240Pu/239Pu atom ratios ranged from 0.151 to 0.353. Besides, the Pacific Proving Ground (PPG) close-in fallout and the global fallout were recognized as two primary sources of Pu in these samples. The 239+240Pu activity concentration as well as the PPG contribution showed similar trends as the Kuroshio intrusion path and the coastal currents in the China Seas, illustrating long-range transport and consuming of PPG derived Pu in the coastal China Seas. Moreover, accumulation of PPG sourced Pu in the Beibu Gulf were observed and was attributed to the continuous invasion of the high isotopic Pu that remobilized from the South China Sea (SCS).

Source term inversion coupling Kernel Principal Component Analysis, Whale Optimization Algorithm, and Backpropagation Neural Networks (KPCA-WOA-BPNN) for complex dispersion scenarios

Accurate and rapid source term estimation is critical for consequence assessment and emergency decision-making in nuclear accidents. Neural network methods provide a promising approach to achieving this goal, but they are mainly demonstrated in ideal scenarios with flat terrain. In this study, a source term inversion model combining the Kernel Principal Component Analysis, the Whale Optimization Algorithm, and the Backpropagation Neural Networks (KPCA-WOA-BPNN) was proposed for source term inversion in a more realistic scenario with complex terrain. The method was validated against two simulated release scenarios based on the meteorology and topography of a real Chinese nuclear power plant. A comprehensive sensitivity analysis of the position distribution, quantity, and quality of measurement sites and the four input parameters was conducted. The results revealed that the relative error of the KPCA-WOA-BPNN was below 2% for both scenarios. The sites within 1.2 km of the release point are critical for the performance. Even with only 6 sites, the error of the method can be as low as 3.82%. The method is insensitive to the disturbances in wind speed, mix layer height, and release height, but less robust to those in concentration. The method also works with other optimization algorithms and presents low error levels, indicating good extendibility.

Dynamic Dose-Based Emergency Evacuation Model for Enhancing Nuclear Power Plant Emergency Response Strategies

The safe evacuation of residents near a nuclear power plant during a nuclear accident is vital for emergency response planning. To tackle this challenge, considering the dynamic dispersion of radioactive materials in the atmosphere and its impact on evacuation routes under different meteorological conditions is crucial. This paper develops a dynamic dose-based emergency evacuation model (DDEEM), which is an efficient and optimized nuclear accident evacuation model based on dynamic radiological dose calculation, utilizing an improved A* algorithm to determine optimal evacuation routes. The DDEEM takes into account the influence of radiological plume dispersion and path selection on evacuation effectiveness. This study employs the DDEEM to assess radiological consequences and evacuation strategies for students residing 5 km from a Chinese nuclear power plant. Under various meteorological conditions, including the three typical meteorological conditions, random ordered and random unordered meteorological sequences, optimal routes obtained through the DDEEM effectively reduce radiological dose exposure and mitigate radiation hazards. The results indicate that all evacuation paths generated by the DDEEM have a maximum dose of less than 1 mSv. Through simulations, the model’s effectiveness and reliability in dynamic radiological environments in terms of radiological consequences and evacuation analysis is verified. The research provides valuable insights and a practical tool for nuclear power plant emergency decision-making, enhancing emergency management capabilities during nuclear accidents. The DDEEM offers crucial technical support and a solid foundation for developing effective emergency response strategies.

SEM-based study on the impact of safety culture on unsafe behaviors in Chinese nuclear power plants

This paper uses 135 Licensed Operator Event Reports (LOER) from Chinese nuclear plants to analyze how safety culture affects unsafe behaviors in nuclear power plants. On the basis of a modified human factors analysis and classification system (HFACS) framework, structural equation model (SEM) is used to explore the relationship between latent variables at various levels. Correlation tests such as chi-square test are used to analyze the path from safety culture to unsafe behaviors. The role of latent error is clarified. The results show that the ratio of latent errors to active errors is 3.4:1. The key path linking safety culture weaknesses to unsafe behaviors is Organizational Processes → Inadequate Supervision → Physical/Technical Environment → Skill-based Errors. The most influential factors on the latent variables at each level in the HFACS framework are Organizational Processes, Inadequate Supervision, Physical Environment, and Skill-based Errors.

Root cause analysis for cracked pipe in auxiliary system in nuclear power plant

Penetrated cracks were found in succession in 316LN stainless steel elbows in auxiliary system in a Chinese nuclear power plant after about 19 years’ service. In order to clarify the root cause of the cracking, the cracked elbow with nominal diameter of 12 in. was cut and its chemical composition, hardness, microstructure and residual strain were investigated. The results show that this elbow was heavily cold worked during push-bending and the degree of cold work was within 25∼40%. The manufacturer did not obey RCC-M M3317 to solution treat this elbow before delivery. The heavily cold-worked elbow suffered stress corrosion cracking in occluded primary water.

Assessing the potential radiological impacts on Vietnam from a hypothetical accident at a nearby Chinese nuclear power plant

We assess the radiological impact on Vietnam from a hypothetical accident at the Fanchenggang nuclear power plant (F-NPP), 65 km from Vietnam’s Mongcai city. The accident was assumed to release, among other types of radionuclides, 1E + 16 Bq 131I in 24 h. The simulation of radioactive plumes using the FLEXPART model has revealed peak concentrations of radionuclides in the air and dry and wet depositions on the ground marking the passage of radioactive plumes over the receptor sites. The northeast monsoon wind drives the peak dry depositions in winter, while the peak wet depositions are associated mainly with the high monsoon rainfall in summer. The accident impact, reflected in the frequency of plume passage over the receptor site and the resultant radiation dose to people, decreases exponentially with the distance to F-NPP. The impact on Mongcai was most severe, implying people would be advised to stay indoors during plume passage. Meanwhile, at Danang, 630 km south of F-NPP, the impact was insignificant, as plumes rarely passed through, and the maximum dose was as low as the annual dose due to exposure from naturally occurring radionuclides in soils.

The Predictors of Unsafe Behaviors among Nuclear Power Plant Workers: An Investigation Integrating Personality, Cognitive and Attitudinal Factors.

Unsafe behaviors, such as violations and human errors, have long been recognized as the main causes of accidents in nuclear power plants (NPPs). However, personal factors that influence unsafe behaviors among NPP workers have not been well examined, especially in an integrated model. This study proposes an integrated contextual mediated model to examine personality, cognitive and attitudinal predictors of unsafe behaviors among commissioning workers at NPPs. The model was verified using structural equation modeling technique with survey data from 177 commissioning workers in two Chinese NPPs. Results show that personality traits (i.e., conscientiousness, neuroticism, openness and agreeableness), executive function and safety attitudes exerted significant effects on unsafe behaviors. In addition, the effects of agreeableness and executive function were partly mediated by safety attitudes. Both conscientiousness and neuroticism indirectly influenced unsafe behaviors through the mediating role of executive function. The findings shed light on the design of evidence-based interventions for safety performance in NPPs.

Analysis on operational efficiency and its influencing factors of China’s nuclear power plants

After implementing the new reform policy of the electric system in 2015, the market-oriented reform of nuclear power prices has been further deepened, as China's nuclear power plants, like other market participants, have also faced increasingly fierce competition. One critical issue worth investigating is how well these plants perform and the influencing factors. To address that issue, we construct an SBM-ML-Tobit model based on plant-level data over five years, from 2016 to 2020. And for all we know, this is the first study to examine Chinese nuclear power plants' operational efficiency. The empirical results indicate significant differences in operational efficiencies between these plants; the operational efficiency levels of all the plants are improved to varying degrees in the sample interval with the increasingly fierce market competition. In addition, our findings suggest that operational efficiencies of power plants are significantly promoted by capacity utilization, average unit size, and unit capacity factor, significantly suppressed by plant size. Again, the operational efficiency levels of plants with higher unit capacity factors are less adversely affected by plant size. Accordingly, our study provides important policy suggestions for better design of the mechanisms to improve the operational efficiency of China's nuclear power plants.

Russian-Chinese “borders” of security. What does the Beijing’s message of V.V. Putin and Xi Jinping mean?

The signing on February 4, 2022 in Beijing of a joint Russian-Chinese statement "On international relations entering a new era and global sustainable development" and a block of bilateral trade, economic and energy agreements means a qualitative expansion of the scope of the strategic partnership between the two countries. Russia and China politically position themselves not only as a global and regional center of power and security, but also as powers that offer the world the development of common human values and concepts - democracy, indivisible security, openness and equality, oppose the politicization of sports, for the expansion of anti-pandemic measures to combat the common evil of COVID-19. China supported the proposals put forward by Russia on its security guarantees in Europe, which helps to further form a common strategic space of Eurasian security from the western part of the Pacific Ocean to the Eastern European conditional line "Black Sea - Belarus". There is no need to reformat the Russian-Chinese strategic partnership into a military alliance in modern conditions. The economic block of cooperation is based on systemic and mutually beneficial energy cooperation, which is implemented in the increase in successful gas contracts, including transactions for the sale of liquefied natural gas (LNG) and pipeline gas, oil projects and sales, the construction of new power units by Russia at Chinese nuclear power plants (NPPs), and the expansion of supplies coal, etc. In the context of a significant increase in the volume of Russian-Chinese trade in 2021 by a third compared to 2020, the expansion of the practice of settlements in national currencies (ruble - yuan), bypassing the dollar, acquires additional importance. In the face of American threats to shut down the SWIFT international payment system, it is relevant to create an independent Russian-Chinese payment system for transactions that provides not only energy transactions, but also the entire range of bilateral trade, economic and interbank transactions. The formation of the Greater Eurasian Partnership involves a wide range of trade, economic, investment, transport and institutional measures to deepen Eurasian cooperation. The key component in this area is to increase the efficiency of the process of interface between the projects of the Eurasian Economic Union (EAEU) and the Chinese initiative "One Belt and One Road", the implementation of joint mutually beneficial infrastructure projects.

Comparison and Evaluation of Domestic and Foreign Radiation Environmental Standards for Nuclear Power Plants

With the development of the nuclear energy industry and the increasing demand for environmental protection, the impact of nuclear power plant radiation on the environment has gradually entered the public view. This article combs the nuclear power plant radiation environmental management systems of several countries, takes the domestic and foreign management of radioactive effluent discharge from nuclear power plants as a starting point, analyses and compares the laws and standards related to radioactive effluents from nuclear power plants in France, the United States, China, and South Korea. In this paper, the management improvement of radioactive effluent discharge system of Chinese nuclear power plants has been discussed.

SELECTION OF LARGE-SCALE NUCLEAR POWER PLANT BASED ON ECONOMIC AND RELIABILITY ASPECTS IN INDONESIAN POWER SYSTEM

Choosing the Indonesia's power systems that are suitable with the large-scale nuclear power plant (NPP) and the NPP's vendor country are crucial problems faced by Indonesian government. Therefore, this research analyzes the NPP impact on the power system reliability to choose the suitable power systems and the NPP economics of each possible vendor country to choose the optimal vendor that provides minimize cost. This research uses two electricity price scenarios: electricity production cost (scenario 1) and adjustment tariff (scenario 2). The results show that only Sumatra and Java-Bali system can be connected with the NPP. For both of these systems, Japanese NPP is not economical to be developed because it provides a levelized unit electricity cost (LUEC) of 0.116 USD/kWh, which is higher than the electricity prices. Meanwhile, Chinese and South Korean NPP is economical to be developed in both systems. For the Java-Bali system, Chinese NPP is the best choice in scenario 1 with a LUEC of 0.036 USD/kWh. In scenario 2, South Korean NPP that has a LUEC of 0.058 USD/kWh becomes the best choice because it has better public perception than Chinese. For the Sumatra system, South Korean NPP is the best choice in both scenarios.Keywords: Large-scale NPP selection, Indonesia power system, Reliability, Minimize cost, Electricity priceJEL Classifications: D21, D22, E39DOI: https://doi.org/10.32479/ijeep.11107

Identification of Correlation among Performance Shaping Factors of SPAR-H Method

Standardized Plant Analysis of Risk-Human reliability analysis (SPAR-H) is an internationally known and accepted human reliability analysis (HRA) method in nuclear power plants (NPPs). However, the eight performance shaping factors (PSFs) overlap, resulting in the double count or over estimation of the human error probabilities (HEPs). To improve its PSFs system, 89 human error event reports related to the operation of operators in the main control room were collected from 219 operating event reports of Chinese NPPs from 2007 to 2017. The correlation among the PSFs was then studied. Therein, three kinds of data mining methods, i.e., association rule analysis, exploratory factor analysis and Pearson correlation analysis, were used. Results show that: a. there is a significant correlation among complexity, stress/stressor, fitness for duty and available time, in which the c the complexity correlates with stress/stressor and fitness for duty, the fitness for duty correlates with stress/stressor, and the stress/stressor correlates with available time; (2) there also exists correlation among work process, procedure, ergonomics/HMI and experience/training. In the event involving the procedure, ergonomics/HMI or experience/training, work process is involved with a high probability. These findings can be used as the reference in the improvement of the PSFs system of SPAR-H and as the basis in the quantitative study of the cause-and–effect dependences among the PSFs.

Distributed parameter modeling for the steam generator in the nuclear power plant

Steam generator is an important equipment in nuclear power plants. This paper investigates the dynamics and heat transfer process in the vertical U-tube natural circulation steam generator. The steam generator under study is divided into four regions, i.e., the hot leg, the cold leg, the steam separator and the saturated steam chamber. Correspondingly, the mass, momentum and energy conservation equations are derived with distributed parameter modeling approach. The model system is validated with the history operation data from a Chinese nuclear power plant. The calculated thermodynamic properties of the saturated steam at the outlet of the steam generator are found to agree well with the measured values, which indirectly validates accuracy of the model system. Model-based dynamic simulation software for the steam generator is developed with which the heat transfer coefficient distribution, the pressure distribution, the temperature distribution, and the speed distribution of the working medium are obtained in real time.

Case Study of the Excessive Vibration of the Medium and High Speed Motors in Circulating Water Filtration System

In one Chinese nuclear power plant, the problem of excessive vibration of medium and high-speed motors(MHMs) in the Circulating Water Filtration System (CFI) frequently occurred during the reactor power operation level. Excessive motor vibration caused the motors to trip, further causing the CFI to shut down automatically. Through a series of theoretical studies and experimental demonstrations, this paper finds out the root cause of excessive vibration of MHMs. The reason is that there are defects in the design and installation of motors, and the motors’ installation methods do not meet the operating requirements. To solve the problem, we designed a support frame with adjustable supporting forces and determined its optimal supporting force through a large number of experiments. Compare the motors’ vibration data before and after the installation of the support frame, and it can see that the support frame fundamentally solves the problem of high vibration of MHMs, and improves the reliability and safety of the units. The support frame designed in this paper also provides a good demonstration of solving similar problems.

Validation and sensitivity study of Micro-SWIFT SPRAY against wind tunnel experiments for air dispersion modeling with both heterogeneous topography and complex building layouts

Micro-SWIFT SPRAY (MSS) is a 3D Lagrangian particle dispersion model that maintains a good balance between accuracy and computational cost. However, its capabilities for air dispersion modeling in the presence of both complex topography and high building densities have not been investigated for nuclear emergency response. In this study, MSS is systematically evaluated against two wind tunnel experiments that simulate a typical Chinese nuclear power plant with the above two features. The MSS predictions are compared with both 2D horizontal and vertical measurements. Sensitivity studies are performed with respect to the particle number, the lower bound of the turbulence intensity, and the horizontal and vertical grid size. The results demonstrate that ground-level predictions of both wind and radionuclide concentrations are in satisfactory agreement with the measurements under optimized parameter values. The vertical predictions exhibit site-dependent accuracy, but generally consistent tendencies. The default lower bound of the turbulence intensity in MSS may be insufficient for reproducing the correct plume width observed in the wind tunnel experiments. An increased lower bound is suggested to solve this problem. In addition, artificially high concentrations may arise near steep slopes if large horizontal/vertical grid sizes are used. Suitable parameters for preventing this problem are also provided.

Performance analysis of the SPRHRS for the 1000 MWe class PWR in coping with station black out

In order to improve the safety and reliability of the Chinese nuclear power plants (NPP), an innovative passive nuclear safety design, the secondary passive residual heat removal system (SPRHRS) is proposed for the light water reactors in China. Previous research work has shown that under design-basis accidents, SPRHRS can mitigate the results by partially or completely replacing the traditional emergency water cooling system. However, the Fukushima Daiichi nuclear power plant accident implies necessity of further assessments of NPPs capability to withstand threats resulting from accidents beyond design-basis accidents. In this study, the nodalization of a 1000 MW class PWR with the SPRHRS design was conducted using RELAP5/MOD3.4. Responses of the PWR under the loss of heat sink accident caused by the station blackout (SBO) was analyzed. The results showed that the residual heat can be effectively removed by the SPRHRS under SBO. In addition, sensitivity studies about the effects of the coolant tank volume and the isolation valve opening condition of the SPRHRS on its residual heat removal capability were also performed. The results indicate that these two main design elements have significant influence on the operation characteristics of SPRHRS. For the SPRHRS design in this study, the appropriate value of the coolant tank volume is 400 m3 and the appropriate valve opening signal is set to be triggered when the SG shell side collapsed liquid level drops lower than 20% of its full value. The present work would be instructive for the design of passive safety systems of Chinese NPPs.

Environmental beliefs and public acceptance of nuclear energy in China: A moderated mediation analysis

Nuclear energy facility development in China has become controversial amid widespread environmental concerns. The present study examines how environmental beliefs influence public acceptance of nuclear energy in the context of China. In the current study, we test the mediation effect of nuclear engagement and test place attachment as a moderator based on cognitive-affective processing system theory. Our data have been obtained from an online survey, using a sample consisting of 516 individuals with experience in the public participation activities in Chinese nuclear power plant projects. The empirical results show that environmental beliefs are positively and significantly correlated to public acceptance of nuclear energy through the individuals’ nuclear engagement. Place attachment negatively and significantly moderates the direct impact of environmental beliefs on nuclear engagement. In the meantime, the mediating effect of nuclear engagement is weaker when place attachment is high. Significant practical implications are provided in our study for the Chinese governmental authorities.

An accident scenario-based statistical test method for RPS in nuclear power plant

RPS (Reactor Protection System) plays a critical role in assuring safety operation and relieves the consequence of accident in Nuclear Power Plant (NPP). With widely use of digital instrumentation and control (I&C) system, since LingAo phase II, Chinese NPP started the introduction of digital I&C system. After ten years of effort, the first domestic independent researched and developed digital I&C system, which named FirmSys, has been deployed in Yang Jiang NPP and intended to export with 3rd generation HPR1000 reactor to the UK. To achieve this export, the method to satisfy generic design assessment (GDA) requirements from the office for nuclear regulation (ONR) of UK is being explored. Statistical test is a recommendation way for independent confidence-building measure (ICBM) and production excellence (PE) of GDA. According to the requirements of statistical test from standard IEC 60880, and with the analysis of current test method limitation in test coverage and operation state simulation, the content and process design is the key point for statistical test in finite test times. For safety critical software in nuclear power plant, whose probability of failure is very small, the critical operation of dealing with accident for avoiding of disaster by user will rarely happen but requires high reliability. Therefore, the common practice of statistical test could not make a sufficient test for the operation during accident happening, and the cost of test is unacceptable. This paper proposes a scenario-based innovation statistical test method for RPS, and describes the test architecture, process, and achievement. This method uses accident scene as test case that focus on the protection functions, it covers parameters, values, operation states, and protection actions. All selected scenes is designed to occur in their relatively probability, target systems are responding in real input and output environment to prove their protection ability as the accident is really happening. Meanwhile, to test the effectiveness of redundant design, channels are randomly selected for success data transform while others are set failure. At last, an engineering practice with this scenario-based test method is made on FirmSys, the pressure water reactor typical accident scenes LOCA, SGTR and MSLB have been successfully simulated, achieves protection sequence verification with high parameters coverage during parameters constantly variation. This method also provides reference for system verification, reliability evaluation and GDA, and be applied in engineering project.

An integrated framework for analysing operational events in China nuclear power plants

Operational events of nuclear power plants (NPPs) are safety-relevant incidents, which may impair the plant functionality and lead to undesired consequences. Thus, their analysis is important for the safety assessment of NPPs. Although several studies have been conducted on NPPs operational events, there is a lack of an integrated framework that effectively combines qualitative and quantitative analyses of operational events. In this study, a framework for the identification and quantification of root causes of operational events is proposed. The framework includes the root causes identification procedures and an online quantification tool based on Bayesian Network modeling. Thirty-seven unplanned reactor trip (URT) events occurred in Chinese NPPs have been used for the case study and the outcome indicates that this framework can be quite useful: on the one hand, it can support inspection and control of the measures of prevention of operational events and reduction of their occurrences from the perspective of regulatory authorities; on the other hand, it can be embedded within the national nuclear safety administration (NNSA) experience feedback (EF) system as an online support tool for living safety assessment.

Reliability Research Methods on NPP Operators

Several relevant research methods on reliability to Chinese nuclear power plant operators in past over 10 years based on nuclear power plant (NPP) simulator platform are introduced in the paper. The relevant research methods include human cognition reliability model, fuzzy synthetic evaluation math model, and psychology quality research model etc.