•Analyzing human factors events (HFEs) is an important part of operating experience feedback in nuclear power plants (NPPs).•Data mining related to nuclear safety becomes a new domain of study.•A ...data mining framework was proposed for identifying intrinsic correlations among human factors.•Correlation analysis, cluster analysis and association rule mining were conducted for 162 human factors events.
With the continuous increase in the number of operating nuclear power plants (NPPs) in China, the amount of operating experience feedback (OEF) increases significantly. On the other hand, the safe operation of NPPs has become an urgent problem that the National Nuclear Safety Administration (NNSA) must solve. To this end, NNSA established a nationalwide OEF system to improve the safety level of NPPs and strengthen the exchange of operating experience. Analyzing the human factors events (HFEs) is an important part of OEF and it is significant to improve human performance and prevent human error. Data mining has been recognized as an effective way to analyze data. With the continuous increase in operating event reports, data mining related to nuclear safety becomes a new domain of study. In this paper, we propose a data mining framework in support of the OEF system. The framework combines three statistical approaches (i.e., correlation analysis, cluster analysis and association rule mining) for identifying intrinsic correlations among human factors: correlation analysis measures the strength of linear relationship between human factors; cluster analysis classifies human factors into relevant groups; association rule mining identifies associations and causalities among human factors. For illustration, we apply the proposed framework to 162 human factors events (screened out from 313 events collected from the OEF system), and the results reflect the feasibility and effectiveness of the framework in identifying the intrinsic correlations among human factors. Besides, further suggestions for improving human performance and preventing human errors in NPPs are also discussed.
•The analyses of operational event are important for the safety assessment of nuclear power plants (NPPs).•An integrated framework for the identification and quantification of root causes of ...operational events is proposed.•Thirty-seven unplanned reactor trip (URT) events have been used for the case study and the outcome indicates that this framework can be quite useful.•The proposed framework can support inspection and control of the measures of prevention of operational events and reduction of their occurrences.
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.
As the main control room of nuclear power plants (NPPs) has been gradually digitized, new human reliability problems may emerge because of a series of new changes in the cognitive processes, ...behavioral patterns, and error mechanisms of operators. Aiming to address this situation, this paper proposes a method as guidance for human reliability analysis (HRA) of different cognitive Stages. This method first constructs the influencing factors of three cognitive processes, including monitoring, decision-making, and execution of actions, and then evaluates the weights of these influencing factors through an analytic hierarchy process (AHP). In this study, the parameters used in the proposed HRA method were determined by analyzing the test data obtained from a simulation model, and the results demonstrated the rationality and feasibility of the proposed method. A case example using this HRA method was given in which the human error probabilities at three stages in a nuclear power plant (NPP) steam generator tube ruptures (SGTR) accident were obtained. In summary, the proposed method is a simple and feasible HRA tool that can be applied in digital NPP main control rooms (MCRs).
The digital control system (DCS)+state-oriented procedure (SOP) system adopted by China's Ling'ao Phase II nuclear power plant's main control room requires changes to the cognitive process, behavior ...mode, and error mode while triggering new human factors. Therefore, in this paper we present a cognitive reliability model for the DCS+SOP system in the Ling'ao Phase II Nuclear Power Plant's main control room and conduct a human reliability analysis. The model is based on the cognitive process with respect to considering the coordinator's accident recovery effect and obtaining the method of calculating cognitive reliability. We determine impact factors for the three cognitive stages of the operator's and the coordinator's diagnosis, decision making, and operation. We obtain the operator's and the coordinator's weights for each process through an analytic hierarchy process. Using methods of simulation and analyzing the experiment data, we obtain revised coefficients for the cognitive reliability model. Additionally, the trend of the simulation curve indicates the rationality of the model. Finally, we provide an example based on the proposed cognitive reliability model. The process of analyzing the example demonstrates that this method provides a feasible analysis method for the cognitive reliability of the DCS+SOP system in the main control room.
The main control room (MCR) in advanced nuclear power plants (NPPs) has changed from analog to digital control system (DCS). Operation and control have become more automated, centralized, and ...accurate due to the digitalization of NPPs, which has improved the efficiency and security of the system. New issues associated with human reliability inevitably arise due to the adoption of new accident procedures and digitalization of main control rooms in NPPs. The LingAo II NPP is the first digital NPP in China to apply the state-oriented procedure. In order to address issues related to human reliability analysis for DCS and DCS + state-oriented procedure, the Hunan Institute of Technology conducted a research project based on a cooperative agreement with the LingDong Nuclear Power Co. Ltd. This paper is a brief introduction to the project.
Five novel coordination polymers {Ln(OHnic)(Onic)(H2O)5·(OHnicH)·H2O}n OHnicH=6-hydroxynicotinic acid, Ln=La(1), Ce(2), Gd(3); {Ln(OHnic)3(H2O)·3H2O}n Ln=La(4), Pr(5) have been synthesized in aqueous ...solution. Compounds 1–3 display 1D chains and 4, 5 possess 2D plane structures. Display omitted
► Five lanthanide complexes were constructed based on the 6-hydroxynicotinic acid. ► Complexes 1–3 exhibit 1D chains and complexes 4–5 possess 2D plane structures. ► Different coordination modes of the ligands lead to the structural differences.
Two types of novel lanthanide complexes with the 6-hydroxynicotinic acid (OHnicH) {Ln(OHnic)(Onic)(H2O)5·(OHnicH)·H2O}n Ln=La(1), Ce(2), Gd(3) and {Ln(OHnic)3(H2O)·3H2O}n Ln=La(4), Pr(5) have been synthesized and characterized by elemental analyses, IR spectra, UV absorption spectra and single crystal X-ray diffraction. The structures of the as-prepared complexes vary with the different coordination modes of the ligands. In complexes 1–3, the adjacent metal centers are linked by the chelating-bridging tridentate modes of the ligands to form 1D chains; while in 4 and 5, the adjacent metal ions are bridged by the ligands in the chelating-bridging bidentate modes to form dinuclear units, then linked into 1D chains through the ligands in the bridging bidentate modes, and further linked to form 2D plane structures via the bridging tridentate modes of the ligands. Thermostabilities and luminescent properties of the complexes have been discussed in detail.
Two coordination polymers, {Mn(1,10-phen)
2
(3,4-H
2
bptc) · (H
2
O)}
2
n
(1) and {Co
2
(1,10-phen)(3,4-bptc)(H
2
O)
2
· H
2
O}
n
(2) (3,4-H
4
bptc = 3,3′,4,4′-biphenyltetracarboxylic acid, ...1,10-phen = 1,10-phenanthroline), have been prepared and structurally characterized. In both compounds, 3,4-H
2
bptc
2-
and 3,4-bptc
4−
exhibit different coordination modes and lead to various architectures. Compound 1 displays 1-D zigzag chains constructed with hydrogen bonds. Compound 2 exhibits a 2-D layer constructed from bpta
4−
between the dinuclear Co(II) units. The thermal stabilities and magnetic properties are also reported. In addition, 1 was explored as a luminescent material. The carboxylic oxygen atoms act as H-bond acceptors and donors forming a 1-D ladder-like arrangement.
Despite the large number of methods available for deburring the outside of parts, it is difficult to remove burrs from the inside of small and long parts. Here, a new magnetic internal deburring ...method is proposed. This method involves application of a magnetic field-assisted machining process using a magnetic tool. It is a new internal magnetic deburring method for removing only burrs in the internal surfaces of tubes. We experimentally examined the deburring of a drilled hole on the inside of SUS304 stainless steel tubing. This deburring experiment was performed for drill holes 1 mm in diameter. The results showed that such internal burrs could be removed using this magnetic deburring process. The height of the burr was successfully reduced from 104 m to 2.5 m, confirming the effectiveness of this new internal deburring method.
The internal magnetic field-assisted machining process can be applied to inside surface finishing, such as in various types of long slender tubes and bent tubes, as lines of magnetic force can easily ...penetrate nonmagnetic materials. The behaviors of the magnetic tool are greatly influenced by the magnetizing characteristics of the magnetic tool material, the type of magnetic field, and its strength. This report describes a new internal magnetic field-assisted finishing process that uses both an alternating magnetic field and magnetic pin tools. From the experimental and analytical results, the relationship was examined between the magnetizing characteristics of the magnetic pin tool and the machining behaviors of the magnetic pin tools. Moreover, a comparative study of the behaviors of the magnet pin tools produced with SUS304 magnetic pin tool and a rare earth permanent magnet was performed.
This report proposes a new constant-pressure magnetic abrasive finishing process to improve the workpiece form accuracy for precision machining of planar and curved workpieces, based on the machining ...principle of an internal magnetic field-assisted machining process using a magnetic machining jig. This new machining method is a process by which a constant pressure is applied to the magnetic pole of a conventional magnetic brush, and the constant pressure acts on the surface of the workpiece through the magnetic particle brush formed at the magnetic pole surface. Experiments were performed using the conventional magnetic abrasive finishing process and the newly proposed constant pressure magnetic abrasive finishing process to compare the deburring characteristics. A brass disk in which was drilled a hole was used as a workpiece. The results showed that burrs can be removed using this new plane magnetic abrasive finishing process, and this process is more useful than the conventional magnetic brush for improving the form accuracy of the workpiece.
