Safety Performance Of System Research Articles

Maintenance Decision Method for High Temperature Reactor Equipment Group with Expense Ratio Target

The equipment group of high-temperature gas-cooled reactors has a wide variety and a large number. Reasonable maintenance planning is especially important. An effective maintenance management strategy can reduce the number of shutdowns and reduce maintenance expense during equipment operation. The goal of maintenance strategy optimization is to improve the reliability of system, prevent system from failures, and reduce maintenance expense influenced by degradation, that is, to maintain or restore products to the appropriate system reliability, availability, and safety performance with the lowest possible maintenance expense.

Hardware-in-the-Loop Test of an Open-Loop Fuzzy Control Method for Decoupled Electrohydraulic Antilock Braking System

To verify the functionality of an intelligent open-loop fuzzy-logic-based antilock braking system control method for four on-board motor drive electric sport utility vehicle, a hardware-in-the-loop experiment is conducted in this article. The experimental facility includes a novel decoupled electrohydraulic brake test bed characterized by highly nonlinear dynamics and time-varying behavior. It reproduces real pressure dynamics of the brake circuit allowing for simulation of various tire–road adhesions conditions and brake blending scenarios. To cope with degradation of antilock braking system performance induced by unexpected changing environmental conditions, such as road surface, the developed fuzzy control features a very simple yet effective and robust road surface recognition tool with estimation of the peak braking demands. Thus, the fuzzy logic serves as a controller and road surface estimator simultaneously allowing for complex mathematical modeling and feedback control avoidance not sacrificing safety system's performance. The results indicate that the control method manages highly nonlinear and time-variant dynamics of the brake system and offers significant feasibility for optimal slip control at regenerative braking, ensuring fuzzy control's potentiality for real-time application.

Fuzzy smart failure modes and effects analysis to improve safety performance of system: Case study of an aircraft landing system

AbstractFailure modes and effects analysis (FMEA) is a safety and reliability technique that is widely used to evaluate, design, and process a system against diverse possible ways through which the potential failure has a tendency to occur. In conventional FMEA, the risk evaluation is determined by risk priority number (RPN) obtained by multiplying of three risk factors—severity, occurrence, and detection. However, because of many shortages in conventional FMEA, the RPN scores have been widely criticized along issues bothering on ambiguity and vagueness, scoring, appraising, evaluating, and selecting corrective actions. In this paper, we propose a new integrated fuzzy smart FMEA framework where the combination of fuzzy set theory, analytical hierarchy process (AHP), and data envelopment analysis (DEA) is used, respectively, to handle uncertainty and to increase the reliability of the risk assessment. These are achieved by employing a heterogeneous group of experts and determining the efficiency of FMEA mode with adequate priority and corrective actions using RPN, time, and cost as indicators. A numerical example (aircraft landing system) is provided to exemplify the feasibility and effectiveness of the proposed model. The outputs of the proposed model compared with the conventional risk assessment technique results show its effectiveness, reliability, and propensity for real applications.

Composite risk index: the new Safety Performance Indicator of risk exposure

Conceptually, all safety programmes desire accurate safety risk quantification in order to provide a meaningful expression of risk. As there are typically, multiple safety risks associated with a system or event, the quantification of total safety risk is a major challenge. One possible way to define and accept the total safety risk of any system is using the concept of a composite risk estimate. This paper represents development of the new safety performance indicator and overall methodology that could be used to measure the performance of European ATM systems as a whole and its individual entities. It describes the computation of the Composite Risk Index (CRI), logic behind it, its use (on the example EUROCONTROL Member States) and limitations and areas of potential improvement. CRI represents a cumulative risk value calculated aggregating all reported, assessed and severity classified key safety-related incidents to form an index. This measure of risk exposure is based on probability and severity that considers the human perception of equivalent risk. Overall idea behind CRI is that the performance of safety system can be analysed within three important broad categories: the quality of reporting system with reporting entity, measured risks within the system, and human perception of risk.

Analiza merenja performansi sistema bezbednosti i zdravlja na radu u rudarsko energetskom kompleksu

In modern mining complexes, the amount of available information on the performance of occupational health and safety systems is constantly increasing. Measurement and evaluation of system performance, as well as the need to develop a better measurement model, arises primarily due to necessity of the improvement of occupational health and safety. The scope of the model aiming to maturity analysis of safety performance measurement, which was applied in the research whose results are presented in this paper, included the performance measurement practice, the commitment and culture of performance measurement and the use of measurement results. In addition to the three basic topics mentioned, an assessment related to the state of the occupational health and safety system was added. As a result of the application of the proposed model, an overall maturity score was obtained. This paper presents the results of the maturity analysis of occupational health and safety system performance measurement in the company TE-KO "Kostolac", which identifies areas that will be given special attention in the future in terms of improving the management of occupational health and safety.

Effects of proof tests on the safety performance of safety-instrumented systems

Effects of proof tests on the safety performance of safety-instrumented systems

Effects of proof tests on the safety performance of safety-instrumented systems

The imperfection in the values of the average probability of failure on demand (PFDavg) creates uncertainty about the effectiveness of safety-instrumented system (SIS). To overcome this problem, many parameters such as dangerous failures, common cause failures, diagnostic coverage rate and proof tests are taken into consideration. In order to emphasise the importance of the proof tests and show their effects on the safety performance of the SIS, a new analytical formula is developed in this study. The impact of these tests on the SIS's allocation of the safe integrity level (SIL) is shown through the results obtained in the present research.

The most difficult at-fault fatal crashes to avoid with current active safety technology

ObjectiveWe studied which current fatal at-fault crashes would occur despite the most advanced current active safety devices (up to SAE level 2 of driving automation) and how frequent these crashes would be. MethodsWe carried out a cross-sectional study of passenger cars that were first registered during the period 1st January 2010 to 31st December 2017 in Finland. To gain the true exposure for these cars, we accessed the national Vehicular and Driver Data Register to obtain the mileage information and the registration count for the study period of 2010-17. Similarly, we accessed the registry of Finnish road accident investigation teams and included all fatal at-fault crashes among the cars in our study for the same period. We used a real world reference technology for each active safety system in our analysis and chose one car brand as an example. This gave us exact system specifications and enabled testing the operation of the systems on the road. We performed field tests to gain further information on the precise operation of the safety systems in different operating conditions. Finally, we gathered all information on the studied active safety systems and analyzed the investigated at-fault fatal crashes case-by-case using our four level method. ResultsCars in our study were the primary party in 113 investigated fatal accidents during the years 2010-17. In 87 of the accidents, the leading cause of death was the injuries due to the crash, and these cases were classified as “unavoidable” (n = 58, 67 %), “avoidable” (n = 26, 30 %) or unsolved (n = 3, 3 %). Of the 58 “unavoidable” crashes 21 (36 %) were suicides, 21 (36%) involved active driver input which would have prevented the safety system operation, 15 (17 %) featured circumstances beyond the safety system performance and in one loss-of-control crash the driver had disabled the relevant safety system (electronic stability control). The registration years of the cars in our study (2010-17) totaled 3,772,864 and during this period, the cars travelled 75.9 billion kilometers. The crash incidence of the “unavoidable” at-fault fatal crashes was 0.76-0.80 fatal crashes per billion kilometers and 15-16 fatal crashes per million registration years. ConclusionsWe calculated a crash incidence for the “unavoidable” crashes which was 20–27% smaller than the observed crash rate of ESC-fitted passenger cars in our previous study. We concluded that suicides, active driver input until the crash, and challenging weather and road conditions are the most difficult factors for current active safety systems. Our analysis did not account for issues such as system usability or driver acceptance and therefore our results should be regarded as something that is currently theoretically achievable. However, the observed incidence is a good reference for automated driving development and the crash rate of automated cars.

Embedding corporate sustainability: An empirical analysis of the antecedents of organization citizenship behavior

AbstractThe relation between organizational citizenship behavior (OCB) and the performance of both safety and environmental management systems has led researchers to investigate the drivers of safety‐specific and environmental‐oriented OCB. However, although the management of environmental and safety issues is often fully integrated into organizational and managerial practice, a holistic perspective of the drivers of health, safety, and environmental (HSE)‐oriented OCB is still lacking. Thus, the aim of the present study is to investigate the antecedents of HSE‐related OCB (OCBHSE). Drawing on both the OCB and sustainability literature, data from 135 manager–direct report dyads collected from eight large Italian companies are analyzed, to assess the effect of both situation‐related antecedents (i.e., organizational ambidexterity and leadership style) and person‐related antecedents (i.e., prosocial values) on prosocial and proactive OCBHSE. Organizational ambidexterity emerges as a direct situation‐related antecedent of both prosocial and proactive OCBHSE, whereas management by exception and passive leadership have a negative effect on the OCBHSE in direct reports. Surprisingly, transformational and contingent reward leadership styles do not emerge as significant drivers of OCBHSE. In terms of person‐related antecedents, the results highlight that prosocial values in direct reports significantly influence prosocial but not proactive OCBHSE. Finally, as OCBHSE is conceptualized in the study as a dimension that is complementary to formal HSE management structures, our findings can contribute to the general organizational effort to improve HSE performance.

Estimation of tire–road friction for road vehicles: a time delay neural network approach

The performance of vehicle active safety systems is dependent on the friction force arising from the contact of tires and the road surface. Therefore, an adequate knowledge of the tire–road friction coefficient is of great importance to achieve a good performance of different vehicle control systems. This paper deals with the tire–road friction coefficient estimation problem through the knowledge of lateral tire force. A time delay neural network (TDNN) is adopted for the proposed estimation design. The TDNN aims at detecting road friction coefficient under lateral force excitations avoiding the use of standard mathematical tire models, which may provide a more efficient method with robust results. Moreover, the approach is able to estimate the road friction at each wheel independently, instead of using lumped axle models simplifications. Simulations based on a realistic vehicle model are carried out on different road surfaces and driving maneuvers to verify the effectiveness of the proposed estimation method. The results are compared with a classical approach, a model-based method modeled as a nonlinear regression.

Physiological Driver Monitoring Using Capacitively Coupled and Radar Sensors

Unobtrusive monitoring of drivers’ physiological parameters is a topic gaining interest, potentially allowing to improve the performance of safety systems to prevent accidents, as well as to improve the driver’s experience or provide health-related services. In this article, two unobtrusive sensing techniques are evaluated: capacitively coupled sensing of the electrocardiogram and respiration, and radar-based sensing of heartbeat and respiration. A challenge for use of these techniques in vehicles are the vibrations and other disturbances that occur in vehicles to which they are inherently more sensitive than contact-based sensors. In this work, optimized sensor architectures and signal processing techniques are proposed that significantly improve the robustness to artefacts. Experimental results, conducted under real driving conditions on public roads, demonstrate the feasibility of the proposed approach. R peak sensitivities and positive predictivities higher than 98% both in highway and city traffic, heart rate mean absolute error of 1.02 bpm resp. 2.06 bpm in highway and city traffic and individual beat R-R interval 95% percentile error within ±27.3 ms are demonstrated. The radar experimental results show that respiration can be measured while driving and heartbeat can be recovered from vibration noise using an accelerometer-based motion reduction algorithm.

Brake and pneumatic wheel performance assessment – A new test rig

A fully new test rig is presented for the assessment of the physical performance of a primary vehicle safety system, namely pneumatic wheel and brake. For the accurate design of vehicle brake system, the need is to study not only the brake, but the brake&wheel assembly. This implies the accurate measurement of forces and moments applied both at the brake and at the wheel. This is a relatively complex and never attempted task in the known literature. The new test rig can be used both in the automotive and in the aerospace sectors. The test rig is basically a dynamometer with an unreferenced architecture, given by a special arrangement of load cells. The test rig allows to measure, among other variables, the dissipated power at the brake and the dissipated power at the assembly composed by wheel and brake. The accurate modelling of the new test rig is performed, according to Industry 4.0 paradigms. Measurement uncertainties of the new test rig are analysed. Excellent accuracy is provided by the new test rig.The dynamometer has shown that the pneumatic wheel itself may dissipate up to 30% of the power dissipated by the brake. This unreferenced result is relevant in both the automotive and aerospace fields.

Pemantauan Kinerja Sistem Manajemen Kesehatan Keselamatan Kerja Lindung Lingkungan berdasarkan ISO 45001, 14001 dan 9001 di KSO CESL

Monitoring Performance of Occupational Health Safety and Environmental Protection Management System (OHSEMS) Based on ISO 45001, 14001 and 9001 is a methodological approach to managing interaction for implementation policies, processes, and regulations. Risk identification modeling used to ensure that activities can run properly in accordance with regulations and standards which are part of the performance management system measurement. Risk control modeling as a verification tool for OHSE events in drilling activities as much as 90, producing 325. Stakeholder regulations as many as 27 with total expectations 108 out of a total of 28 revisions with a total expectation of 225 in standard regulatory database modeling. OHSEMS improvement uses data on OHSE events from 2013 to June 2018. Drilling activities have 16 events with a number of standard regulations 14 and the number of suggestions for improvement 23, the number of recommended suggestion as many as 16. Production activities there are 25 occurrences of the number of standard regulations 16 with suggestions improvements 42 and recommendations for improvements was 25. In the OHSEMS improvement in drilling activities based on OHSE events is to socialize drilling work procedures. In production activities to reduce the occurrence of oil spills that can cause environmental impacts, make improvements to facilities as well as emergency response prevention training can be done to control events caused by human factors and production equipment

Emergency core cooling system performance criteria for Multi-Layered Silicon Carbide nuclear fuel cladding

Multi-layered Silicon Carbide (SiC) cladding has been proposed to replace the current Zircaloy (Zr) cladding in existing nuclear power plants. Due to its ceramic property, SiC may have a different failure mechanism from that of metallic Zr clad. This characteristic should be considered in designing the plant’s safety system performance, such that the fuel’s integrity is reasonably assured during accident scenarios.This paper aims at optimizing the Emergency Core Cooling System (ECCS) performance criteria in mitigating LBLOCA accidents at a Pressurized Water Reactor (PWR) using the uranium dioxide fuel and duplex or triplex SiC cladding structures. Clad failures by brittle fractures and thermal degradation were modeled in a fuel analysis code. This fuel model was coupled with the RELAP5 plant model by adapting the fuel’s mesh configuration and formulating the effective heat transfer coefficients. A model to quantify the likelihood of clad functional failure as a combination of individual layer fractures at various axial positions was proposed. Updated SiC material properties were gathered from recent reference studies. Clad reliability estimates using the proposed model were compared with the estimates obtained using other models. The results were used to relax the criterion of required actuation timing of ECCS, such that the risk of the new plant design is less or equal to that of the initial plant configuration.Triplex clad was more reliable than duplex clad and Zr, reducing the conditional core damage probability by three orders of magnitude in the reference LBLOCA scenario. Compressive stresses due to irradiation swelling played the determining role in the vulnerabilities of each clad design. The duplex clad was vulnerable to pressure-loading stresses while triplex clad was prone to fail due to thermal shocks experienced during the LOCA reflood phase. Additionally, it was concluded that the most vulnerable axial fuel rod location in the reference LBLOCA scenario was located at the highest axial power peaking location.A sensitivity study on the ECCS timing density was conducted. The results showed that ECCS actuation timing could be extended from the initial technical specification, without increasing the fuel damage likelihood. The time extension was distributed in the order of several hundreds of seconds, which was comparable with time extensions offered by FeCrAl and Cr-coated-Zr clad designs in LBLOCA scenarios. This time extension may potentially reduce the failure probabilities of EDGs and pumps, hence improving the plant safety further.

Recent achievement and future prospects of the ATLAS program

As a critical thermal-hydraulic test facility, the ATLAS facility has been widely utilized since its first commission test in 2006 to resolve urgent safety concerns raised by nuclear industries and regulatory body, to verify the performance of new safety systems, to validate safety analysis codes, and to provide a cooperation network for developing safety analysis capabilities. In the first phase of the ATLAS program, major R&D efforts were put into producing code validation data to support the standard design approval of the APR1400 when design basis accident (DBA) scenarios were the main interest of the program. In the following phase, the ATLAS program’s focus shifted to beyond DBA scenarios, and the OECD-ATLAS international joint project started reflecting the safety concerns of many NEA countries following the Fukushima Daiichi disaster in 2011. In this paper, the current status of the ATLAS program, including the OECD-ATLAS Phase-1 and 2 projects, are briefly described together with their major outcomes. The next R&D program based on the ATLAS platform is also briefly discussed.

Path Analysis of Causal Factors Influencing Marine Traffic Accident via Structural Equation Numerical Modeling

Many causal factors to marine traffic accidents (MTAs) influence each other and have associated effects. It is necessary to quantify the correlation path mode of these factors to improve accident prevention measures and their effects. In the application of human factors to accident mechanisms, the complex structural chains on causes to MTA systems were analyzed by combining the human failure analysis and classification system (HFACS) with theoretical structural equation modeling (SEM). First, the accident causation model was established as a human error analysis classification in sight of a MTA, and the constituent elements of the causes of the accident were conducted. Second, a hypothetical model of human factors classification was proposed by applying the practice of the structural model. Third, with the data resources from ship accident cases, this hypothetical model was discussed and simulated, and as a result, the relationship path dependency mode between the latent independent variable of the accident was quantitatively analyzed based on the observed dependent variable of human behavior. Application examples show that relationships in the HFACS are verified and in line with the path developing mode, and resource management factors have a pronounced influence and a strong relevance to the causal chain of the accidents. Appropriate algorithms for the theoretical model can be used to numerically understand the safety performance of marine traffic systems under different parameters through mathematical analysis. Hierarchical assumptions in the HFACS model are quantitatively verified.

Modeling Pedestrian Injury Severity in Pedestrian-Vehicle Crashes in Rural and Urban Areas: Mixed Logit Model Approach

Pedestrian-vehicle crashes are more likely to result in severe pedestrian incapacitating injuries and fatalities than other types of crashes. In this study, mixed logit models are developed to investigate and identify significant contributing factors to the pedestrian injury severity in pedestrian-vehicle crashes in both rural and urban areas in North Carolina, United States. Pedestrian-vehicle crash data from the Highway Safety Information System database from 2005 to 2012 are collected and used in this study. Crash injury severities are classified into five categories: fatality; injury class 1 (disabling injury); injury class 2 (evident injury); injury class 3 (possible injury); and no injury (property damage only). The estimation results show that factors such as a bad driver’s physical condition, heavy trucks, dark light condition, speed limit between 35 and 50 mph and speed limit above 50 mph will significantly increase pedestrian injury severities in both rural and urban areas. The developed model and analysis results provide insights on developing effective countermeasures to reduce pedestrian injury severities in pedestrian-vehicle crashes and improve traffic system safety performance.

Experimental investigation of LWR passive safety systems performance at the INKA test facility

INKA is a test facility designed by Framatome and built in the technical center in Karlstein. The original objective for establishing this test rig was the investigation of the performance of the passive safety systems developed in a new Framatome Boiling Water Reactor (BWR) design – KERENA. INKA was constructed in the scale of 1:1 in heights while the total volume of the containment was replicated in 1:24. Since the geometries of particular safety systems are faithfully reflected, their actual performance in the original plant can be investigated at the full scale. Due to the unquestionable interest of the nuclear community in the inherent safety, not only new BWR and PWR designs are equipped with the passive systems, but also particular passive solutions are considered to be applied into the already existing Light Water Reactors (LWR). In this context and due to the fact that both, single component tests and integral tests can be conducted at INKA, the facility can be employed for a demonstration/qualification of a large range of passive safety systems foreseen for quite different types of LWRs. Hence, the goal of the EASY project was the experimental confirmation of the passive systems performance and the analysis of their interactions between each other in the integral tests. Besides, the overarching target of all tests performed at INKA is provision of data for codes validation. This paper presents major outcomes and conclusions drawn on the basis of EASY project results.

Non-technical skill development strategy to enhance safety performance of railway system: an interpretive structural modelling approach

Despite massive technological advancement and up gradation in transport sector, operational safety largely depends on the front-line operator. The manager of transport industry, remains chronically stressed to ensure system safety along with productivity. It is always a challenge for them to deliver system safety while managing routine task along with providing system resilience against emergencies, abnormalities along with occasional operator's fallibility. To handle these challenges effectively, development of suitable non-technical skill for front line managers has been attempted in the paper. Generic NTS proposed could provide the necessary fillip to their technical skill and likely to enhance their overall managerial skill. This shall also demonstrable commitment for adopting NTS for the entire organisation to enhance safety and productivity.

Non-technical skill development strategy to enhance safety performance of railway system: an interpretive structural modelling approach

Despite massive technological advancement and up gradation in transport sector, operational safety largely depends on the front-line operator. The manager of transport industry, remains chronically stressed to ensure system safety along with productivity. It is always a challenge for them to deliver system safety while managing routine task along with providing system resilience against emergencies, abnormalities along with occasional operator's fallibility. To handle these challenges effectively, development of suitable non-technical skill for front line managers has been attempted in the paper. Generic NTS proposed could provide the necessary fillip to their technical skill and likely to enhance their overall managerial skill. This shall also demonstrable commitment for adopting NTS for the entire organisation to enhance safety and productivity.