Reliability Of Safety Systems Research Articles

Probabilistic safety analysis of the large primary circuit leakages accident scenarios in the VVER-reactor

Probabilistic safety analysis of the loss of coolant accidents in the VVER-type reactor plant has been performed taking into account the internal initiating events of the reactor primary circuit large leakages. Swedish program code RiskSpectrum PSA was used for probabilistic safety analysis. Logical probabilistic models of the accident scenarios of the large primary circuit leakages in the VVER-type reactor were developed taking into account different operation modes of the power plant unit. Critical paths and probabilities of the accident scenarios occurrence of the large leakages were identified. The critical path of development of the reactor primary circuit large leakages accident with large leakages of 140–346 mm diameters is the accident sequence with a leak in the pipeline to the reactor pressurizer vessel. It has been established that the greatest contribution to the failure of safety functions during this initiating event is made by the failures due to common causes of the supporting systems (cooling and ventilation systems), critical consumers cooling circuit, emergency injection system. The critical path of the accident with large leakages of 346–850 mm diameters is the accident sequence with the rupture of any of the four primary circuit loops. The greatest contribution to the failure of safety functions during this initiating event is made by the failures due to common causes of the emergency injection system elements. Based on the accident analysis, recommendations for increase of performance reliability of safety functions during the large leakages accidents under all operation states of the nuclear power plant unit were given. In order to increase reliability of safety systems, it is necessary to eliminate failures due to common causes of equipment, increase the reliability of operation of supporting systems, change the maintenance and checking equipment procedures.

Fuzzy reliability algorithm for the shutdown system of research reactor

Abstract Probabilistic safety assessment (PSA) has been applied to evaluate the safety of nuclear reactor systems. The results of PSA are used by designers, utilities and regulatory body to confirm the reactor design, to change operation procedures, to enhance the reliability of safety systems, or to modify regulation. Fault tree analysis (FTA) has been used as a deductive means for PSA. System components are assumed to always have defined failure probabilities; however, in reality this assumption is questionable and sometimes there is insufficient data about the failure probability of some components. To solve this problem, fuzzy approaches have been proposed and implemented. The aim of this study is to apply a fuzzy reliability algorithm to estimate basic events failure probabilities for the shutdown system of a research reactor. The reactor is a 22 MW light water open pool type material test reactor and the shutdown system is responsible for the fast shutdown of the reactor whenever safety limits are exceeded. Then, to illustrate the ability of the algorithm, the results are compared with real basic event failure probabilities. The results verify the competence of the algorithm and confirm that it can be applied as an alternative method when quantitative data are not available. Also, a risk importance measure is done on the fault tree of the shutdown system to illustrate which components need to be focused for improvements to achieve the safe operation of shutdown system.

Arduino-Based Safety System for Gas Flame Monitoring, Leakage Detection, and Utensil Presence Using Sensor Integration and SMS Alerts

Abstract: In this research project, we present an innovative Arduino-based safety system designed to enhance household gas safety by monitoring gas flame, detecting gas leakage, and ensuring the presence of utensils in the cooking area. By integrating various sensors such as a flame sensor, gas leakage sensor, and ultrasonic sensor, coupled with servo motor control and GSM technology, our system provides real-time monitoring and proactive response to potential hazards. This project showcases the integration of hardware components and intelligent control algorithms, enabling an efficient and reliable safety system. The use of Arduino as the central control unit provides a flexible and cost-effective solution for gas safety applications. Experimental results demonstrate the effectiveness of our system in detecting potential hazards, triggering appropriate actions, and notifying users via SMS alerts.

Evaluation of possible leakage causes in a natural circulation helium loop

With the development of IVth. Generation nuclear reactors, the safety systems have to be adjusted to comply with the specific requirements of these new reactor designs and handle any nuclear accident in the best possible way. The Fukushima accident showed that the decay heat present after the reactor shutdown can still be a threat, and robust and reliable safety systems must be introduced. The natural circulation loop represents such a system since the main driving force is partially supplied by the decay heat itself. To investigate the possibilities of using a natural circulation system, we built an experimental helium loop, where the thermodynamic and hydraulic properties of the system were studied. During the measurements, coolant leakages were observed. The scale of the experimental device is close to the scale of a real application; therefore, any unexpected behavior should be properly investigated and reported, especially if the phenomena involve concerns about possible coolant leakage. This paper reports and analyzes measured leakage rates during several measurements on a large-scale, high-temperature, high-pressure natural circulation loop.

Earth Air Thermoelectric Generators

This study analyzes and examines the Earth-Air Thermoelectricity Generator (TTEJ), which works with earth temperature and is recommended to be used peculiarly in safety systems, both theoretically and experientially. To examine how TTEJ functions in natural conditions, temperatures at the soil depth and soil surface were equal to the length of the generator, and ΔT temperature differences were measured and modeled throughout four seasons in five different precincts in Ankara. To create the environment to measure and analyze how TTEJ functions in natural conditions, in addition to the standard TEJ theory, to design a thermoelectric earth-air generator or to calculate its parameters, a mathematical model of TTEJ is created by embodying both thermic processes and the thermoelectric generator that functions conveniently for these processes. The thermoelectric parameters such as power P(W) produced by the generator based on T, resistance U(V), and current I(A) are calculated using a custom experiment mechanism built specifically for this research, and the results are compared to theoretical results. The outcome of theoretical and experimental results is congruence. The custom earth-air generator that is created as a model implementation can provide a reliable safety system that is presented and detected. Thus, it is concluded that without any requirements for an electricity cable, it is possible to create a system that can work via TTEJ by generating electricity with the help of the earth's temperature in the event of a property violation or other security-related issue and notifying the security units. Also, it is predicted that, as an innovative and environment-friendly product, TTEJ will be used in various fields of work, especially in military applications.

Failure assessment in lithium-ion battery packs in electric vehicles using the failure modes and effects analysis (FMEA) approach

The use of batteries in electric cars comes with inherent risks. As the crucial component of these vehicles, batteries must possess a highly dependable safety system to ensure the safety of users. To establish such a reliable safety system, a comprehensive analysis of potential battery failures is carried out. This research examines various failure modes and their effects, investigates the causes behind them, and quantifies the associated risks. The failure modes and effect analysis (FMEA) method is employed to classify these failures based on priority numbers. By studying 28 accident reports involving electric vehicles, data is collected to identify potential failure modes and evaluate their risks. The results obtained from the FMEA assessment are used to propose safety measures, considering the importance of the potential failure modes as indicated by their risk priority number (RPN). The design incorporates safeguards against mechanical stress, external short circuits, and thermal runaway incidents. The findings of this study enhance our understanding of electric vehicle (EV) battery safety and offer valuable insights to EV manufacturers, regulators, and policymakers, aiding them in the development of safer and more reliable electric vehicles.

Validation of scenario-based virtual safety testing using low-cost sensor-based instrumented vehicle

Autonomous vehicle (AV) requires millions of miles on road to test the reliability of safety systems. It is also difficult to test the AV for critical scenarios which are rare but will endanger road users. Therefore, virtual safety testing simulation platforms are introduced to test the safety systems of the autonomous vehicles in critical scenarios. However, developing the virtual safety testing simulation platform requires information about the environment and driving data from the real world. Besides, it is challenging to build a system to collect driving data which is normally cost intensive especially in developing countries. Paradoxically, these developing countries have poor traffic environment which can provide valuable scenarios for safety testing test cases. Therefore, in this paper, a scenario-based testing using virtual simulation platform is developed using data captured by a low-cost sensor-based instrumented vehicle. The instrumented vehicle is built by low-cost off-the-shelf components for the testing purpose. The instrumented vehicle is used for validation process in IPG CarMaker’s vehicle model using SAE standards. Then, the validated vehicle model is used as an autonomous vehicle in IPG CarMaker for the virtual scenario-based safety testing. The whole validation process from data collection to data logging is carried out using various economic sensors instead of a single industrial system. This approach greatly reduce the cost of the instrumented vehicle and the result of the scenario-based testing shows that the virtual scenarios developed in IPG CarMaker can be used for validation purpose with actual scenarios using low-cost sensor based instrumented vehicle as low as 4% root mean square percentage error.

Проблемы оценки риска по результатам HAZOP-исследования

HAZOP hazard identification method, which considers the parts of a system individually, has disadvantages that limit its application to structurally complex technological systems. In these cases, the simplified risk analysis methods such as FMEA, FMECA, etc. cannot be correct. To assess the risk of complex systems, it is recommended to conduct additional studies using the methods such as FTA and ETA, and other more rigorous methods. Additional studies require a significant investment of time, which is often limited by design time. Limitations can be overcome by using the information technology. The use of the FTA and ETA methods as the methods for identifying hazards directly in HAZOP study process allows to supplement HAZOP procedure with an analysis of deviations in the characteristics of the system elements from the design goals, their causes, and hazardous consequences in the entire technological system. It becomes possible, based on the results of HAZOP studies, to automatically build and analyze a combined fault tree and event tree. To determine the permissible probability of a hazardous event, a calibrated risk graph and the results of accident modeling are used. Automated analysis of the combined fault tree and event tree will allow to consider solution options, determine the risk created by the controlled equipment, select the systems for its consistent reduction and optimal requirements for the functions and reliability of safety systems used to reduce the risk.

METHOD OF QUALIFICATION OF PASSIVE SAFETY SYSTEMS OF MODULAR NUCLEAR REACTORS WITH CIRCULATION CIRCUIT FLOWS

Low-power modular reactors are a promising direction for increasing the safety of nuclear power, because accident management in modular reactors is carried out only by passive safety systems (without electric pumps). Critical for the safety of modular reactors are accidents with a violation of the tightness of the natural circulation circuits of passive safety systems. The main limitations of using traditional accident modeling approaches with deterministic codes to qualify the reliability and operability of passive safety systems of modular reactors are related to the possibility of negative effects of "code differences" and "code user differences", as well as the unfoundedness of code verification/validation results. An original qualification method has been developed to ensure the safety conditions of the passive safety systems of the Westinghouse low-power modular reactor (SMR) in the event of accidents with a violation of the tightness of the natural circulation circuits. The assumptions adopted in the developed method ensure the conservatism of qualification results. Based on the preliminary calculation qualification of the natural circulation circuits of the SMR passive safety systems, it was established that for the relative sizes of the leaks, greater than 5% of the pipeline cross-section, a violation of safety conditions and drainage of the active zone may occur less than 24 hours after the start of the accident. It is necessary to modernize the SMR with regard to systems for diagnosing leaks in natural circulation circuits of passive safety systems and isolating damaged sections of circuits.

The use of drones in emergency medicine

In the 21st century, we are experiencing the widespread use of new technologies that are designed to make work and daily life easier. The emergence of unmanned aerial vehicles (UAVs) has also opened up new opportunities for medical rescue support. This paper explores the various aspects of using medical drones to aid rescue operations. These devices can move at high speeds, traverse difficult terrain that ground vehicles cannot, and have many capabilities depending on their equipment. Currently, the use of UAVs is limited to rescue operations of an extreme nature, such as searching for missing individuals in dangerous or vast areas, or providing support during mass events.The paper describes the potential possibilities of using drones in rescue operations, such as delivering critical medicines, first aid equipment, or collecting information on hazards relevant to rescue planning. It is important to note that UAVs are still a relatively new technology that requires reliable safety systems, especially in the context of medical use. Possible threats, such as hacking attacks, collision risks in different environments, and the level of training of personnel involved in UAVs management, were also presented. Additionally, the paper addresses current legal and systemic issues in Poland and the European Union. Lastly, the results of public opinion polls on confi¬dentiality and consent to the use of medical drones were mentioned.

ANALISIS SISTEM PENGAMAN UTAMA UNTUK MENGAMANKAN BUSBAR 150 kV TERHADAP GANGGUAN DI GIS PECATU

GIS (Gas Insulated Switchgear) is a system of connecting and disconnecting the power grid which is packaged in a non-ferrous tube, using gaseous sulfur hexaflouride (SF6) as the insulation medium. The 150 kV of GIS Pecatu is located in Pecatu Village, South Kuta, Badung Regency, Bali Province. This GIS was built to help supply 120 MW of energy because of the load in Badung area, especially Pecatu and Nusa Dua, is increasing. So, it is necessary to know the differential relay current settings when there is a fault of short circuit in GIS Pecatu to produce an effective, selective and reliable safety system.
 When there is a fault of 11.58 kA the relay will work immediately within 0 SI, this proves that the differential relay with Instantaneous characteristics will immediately command a trip when the fault current has surpass the set value. From the calculation results, the setting of the main safety relay has worked in appropriate with the SPLN standard No. 52-1 1984 for the 150 kV system.

A Data Based Method Road Surface Parameters Estimation for Anti-Lock Braking System

Accurate road surface parameter identification is considered essential for selecting the appropriate controlling threshold in the Anti-lock Braking System (ABS) utilized in modern vehicles. This paper presents a data-based method for road surface parameter estimation. The proposed method utilizes a pattern recognition technique that works to estimate the road type during braking. A detailed analysis and related comparison is provided for several pattern recognition techniques such as Support Vector Machine (SVM), K-Nearest Neighbor (KNN), and Decision Tree (DT), which were chosen among previously studied pattern recognition techniques. A model for the ABS system is implemented with MATLAB Simulink, and the required data is extracted to be utilized to train each model individually. After training is complete, a test has been applied in order to obtain the performance of each trained model. In particular, accuracy and sensitivity are utilized to compare the effectiveness of these models, with 96% for the SVM, 95.2% for the DT model, and 94% for the KNN model. Although the SVM classifier accuracy was better than both the KNN and DT classifiers, all classifiers presented a high performance accuracy that proves the possibility of utilizing a data-based method for road surface parameter identification that increases the reliability of safety systems like the ABS.

Building Fire Safety Management Analysis Based On Building Safety System Reliability Assessment Method In Green House Display Building – Cibinong National Research And Innovation Agency, Bogor Regency

Fires should be alerted and anticipated or detected as early as possible. If a fire occurs, it will be fatal such as damage to buildings, infrastructure, To prevent or anticipate fires, detection must be carried out as early as possible and prepared facilities or infrastructure for fire safety. The Green House display building is an exhibition building of living plants from various mountains in Indonesia including the mountains of Java, the mountains of Sumatra, the mountains of Kalimantan, and the mountains of Papua. Plants and soil are taken directly from the associated location. This building is allegedly very prone to fire because there are so many flammable materials such as leaves, wood and others. As well as forests in Indonesia, especially in Kalimantan and Sumatra where fires often occur. Therefore, the application of Building Fire Safety Management in this building must be applied as well as possible. Active protection systems such as fire detection devices for this building cannot use ordinary systems, because in this building, the atmosphere is like mountains with many big trees. The inspection can be carried out by several methods, including analyzing based on applicable standards and analyzing based on the assessment of the reliability of the building safety system referring to the Settlement Research and Development Center, Research and Development Agency PU, Department of Public Works in 2005 (Pd-T-11-2005-C).

Dynamic simulation and analysis of steam dump valve failure using secondary side model of PWR

The safety system reliability is a key issue for the nuclear power plant (NPP), and the steam dump system (SDS) is an important pressure stabilizing system used in Hualong Pressurized Reactor (HPR1000) to enable nuclear steam supply system to accept loss of load without incurring a reactor trip and to remove stored energy and decay heat following a reactor trip without actuation of the steam generator safety valves. The SDS is consisted of many steam dump valves, and its reliability is dominated by the reliability of steam dump valves. During the steam dump interlock inspection test of a NPP, the pressure of the main steam pipe in the second loop appeared shock, which triggered the protection signal because of the high main steam pressure difference between the second and other main steam pipes. The purpose of this study is to simulate the failures and explore the mechanism of SDS failure process. A dynamic simulation model is developed with APROS version 6.10, which includes components between the steam generator (SG) and the main steam valves of NPP. The compressed air leakage failure for the steam dump valve, which causes valve position reduction (0%, 10% and 20%) and adjust speed change, is included in the dynamic simulation, and it causes fluctuations and steady-state errors in system parameters such as the main steam pressure and valve opening position. In the case of 10% and 20% valve position reduction, the main steam pressure fluctuates between 7.3 MPa and 7.45 MPa, and the steady-state errors are about 0.02 MPa. Then, the safety valve will jump in the fluence of water hammer due to the unsteady mass flow rate of condensate water. The pressure can drop to 6.75 MPa caused by safety valve jump, and the safety injection system will be triggered to form a serious accident reaction if the take-off action sustains over 0.13 s. Results of this study would be helpful for the understanding of the SDS failures process and dynamic characteristics of the SDS for nuclear power units, and provide guidance for failure identification and safety system improvement work.

A scoping review of patient safety research carried out in Saudi Arabian hospitals

AbstractBackgroundIn Saudi Arabia, there has been substantial investment in patient safety initiatives.ObjectivesThe objectives of this scoping review were to map the quantity and nature of existing research on patient safety in Saudi Arabian hospitals and to identify gaps in the extant literature.MethodsElectronic searches were completed using five databases. Peer-reviewed studies written in English or Arabic that focused on patient safety in hospitals in Saudi Arabia were reviewed. Studies concerned with measuring and monitoring safety were categorised using the Measuring and Monitoring Safety Framework. The hierarchy of intervention effectiveness was used to categorise interventions studies.ResultsA total of 2489 studies were screened, with 67 meeting the inclusion criteria. In total, 61 (91%) of included studies were focused on the measurement or monitoring of safety. Six studies (9%) considered interventions to improve patient safety. Of these, 31.3% of the studies assessed past harm, 1.5% reliability of safety systems, 7.5% sensitivity to operations, 47.8% anticipation and preparedness, and 3% integration and learning. Of the six intervention studies, one study reported enforcing functions interventions, one simplification and standardisation, two rules and policies, and two studies applied an education and training intervention.ConclusionAs is the case internationally, there is a paucity of evidence on interventions to improve safety in Saudi Arabia. This review has identified areas of strength, redundancy, and gaps in patient safety research in the Saudi Arabia. However, the findings also have implications for the MMS in other healthcare systems.

ROLE OF PASSIVE SAFETY SYSTEMS IN PREVENTION AND MITIGATION OF SEVERE ACCIDENTS AT NUCLEAR POWER PLANTS

Fukushima Daiichi accidents led to the worldwide update of the NPP safety requirements. Particular attention was paid to severe accidents both during the design of new NPP units and during the safety reassessment of existing ones. Performed safety reassessment of operating units was focused on development and implementation of technical means and strategies directed to prevention and/or mitigation of severe accidents. Technical solutions that are used in modern designs of reactor facilities involve several options for providing of heat removal from the core and containment. Such options include heat removal systems from the reactor core and from the containment of reactor facility. Most of such systems are based on passive principals of operation and do not require or require a minimum action of operating personnel. At the same time, reactor facilities that are operated in Ukraine are based on old VVER designs, which do not include passive safety systems for long-term heat removal (especially for the case of total station blackout, which was in the focus during safety reassessments, so-called “stress tests”). Thus, the necessity of such systems at Ukrainian NPPs with VVER-1000 and VVER-440 was discussed together with analysis of existing types of passive systems and their prevalence. Based on the results of performed analysis the feasibility of implementation at Ukrainian NPPs of a passive heat removal system from the core for VVER-1000 and from the confinement for the VVER-440 was identified. The possibility of implementation of such systems at Ukrainian NPPs requires a separate analysis. In addition, a general information on current state of passive systems reliability assessment was described. It should be noted that despite the reliability of passive safety systems is one of the important issues it is still poorly studied and require additional analyses.

Analysis and Estimation of Core Damage Frequency of Flow Blockage and Loss of Coolant Accident: A Case Study of a 10 MW Water-Water Research Reactor-PSA Level 1

Fault trees (FT) and event trees (ET) are widely used in industry to model and evaluate the reliability of safety systems. This work seeks to analyze and estimate the core damage frequency (CDF) due to flow blockage (FB) and loss of coolant accident (LOCA) due to large rupture of primary circuit pipe with respect to a specific 10 MW Water-Water Research Reactor in Ghana using the FT and ET technique. Using FT, the following reactor safety systems: reactor protection system, primary heat removal system, isolation of the reactor pool, emergency core cooling system (ECCS), natural circulation heat removal, and isolation of the containment were evaluated for their dependability. The probabilistic safety assessment (PSA) Level 1 was conducted using a commercial computational tool, system analysis program for practical coherent reliability assessment (SAPHIRE) 7.0. The frequency of an accident resulting in severe core damage for the internal initiating event was estimated to be 2.51e − 4/yr for the large LOCA as well as 1.45e − 4/yr for FB, culminating in a total core damage frequency of 3.96e − 4/yr. The estimated values for the frequencies of core damage were within the expected margins of 1.0e − 5/yr to 1.0e − 4/yr and of identical sequence of the extent as found for similar reactors.

Tragic Choices at Fukushima Daiichi Nuclear Power Plant

AbstractIn high-risk industries, the development of reliable safety systems has made it easy to forget that operators may one day be confronted with dramatic, life-threatening situations. This arti...

A Bayesian framework of inverse uncertainty quantification with principal component analysis and Kriging for the reliability analysis of passive safety systems

In this work, we propose an Inverse Uncertainty Quantification (IUQ) approach to assigning Probability Density Functions (PDFs) to uncertain input parameters of Thermal-Hydraulic (T-H) models used to assess the reliability of passive safety systems. The approach uses experimental data within a Bayesian framework. The application to a RELAP5-3D model of the PERSEO (In-Pool Energy Removal System for Emergency Operation) facility located at SIET laboratory (Piacenza, Italy) is demonstrated. Principal Component Analysis (PCA) is applied for output dimensionality reduction and Kriging meta-modeling is used to emulate the reduced set of RELAP5-3D code outputs. This is done to decrease the computational cost of the Markov Chain Monte Carlo (MCMC) posterior sampling of the uncertain input parameters, which requires a large number of model simulations.

НОВАЯ СИСТЕМА УПРАВЛЕНИЯ И ЗАЩИТЫ РЕАКТОРА SD-TMSR

The current work introduces a reliable safety system based on control rods in addition to the online feed system reactivity control in the Single-fluid Double-zone Thorium-based Molten Salt Reactor (SD-TMSR). The reactivity of the SD-TMSR core is controlled through two systems of control assemblies: (1) the Control Safety Devices (CSD) and (2) the Diverse Safety Devices (DSD). In the present work, the control rods are natural B4C and B4C-90 (with 90% weight content of the main absorbing 10B isotope). Since the numbers and distribution of control assemblies in SD-TMSR have not been studied previously, we proposed a unique distribution as a starting point for this analysis. The distribution of these 25 fuel assemblies with control rods in the SD-TMSR core and their numbering scheme were presented in this paper. Additionally, excess reactivity, control rod worth, and shutdown margin were calculated using Monte Carlo code Serpent2. Analysis results showed that the proposed placement of the control rods will make it possible to compensate for excess reactivity during fuel burnout and emergency shutdown of the reactor.