Safety Assessment Framework Research Articles

Tissue Distribution and Elimination of Ciguatoxins in Tridacna maxima (Tridacnidae, Bivalvia) Fed Gambierdiscus polynesiensis.

Ciguatera is a foodborne disease caused by the consumption of seafood contaminated with ciguatoxins (CTXs). Ciguatera-like poisoning events involving giant clams (Tridacna maxima) are reported occasionally from Pacific islands communities. The present study aimed at providing insights into CTXs tissue distribution and detoxification rate in giant clams exposed to toxic cells of Gambierdiscus polynesiensis, in the framework of seafood safety assessment. In a first experiment, three groups of tissue (viscera, flesh and mantle) were dissected from exposed individuals, and analyzed for their toxicity using the neuroblastoma cell-based assay (CBA-N2a) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses. The viscera, flesh, and mantle were shown to retain 65%, 25%, and 10% of the total toxin burden, respectively. All tissues reached levels above the safety limit recommended for human consumption, suggesting that evisceration alone, a practice widely used among local populations, is not enough to ensure seafood safety. In a second experiment, the toxin content in contaminated giant clams was followed at different time points (0, 2, 4, and 6 days post-exposure). Observations suggest that no toxin elimination is visible in T. maxima throughout 6 days of detoxification.

Using SAFRAN Software to Assess Radiological Hazards from Dismantling of Tammuz-2 Reactor Core at Al-tuwaitha Nuclear Site

The Safety Assessment Framework (SAFRAN) software has implemented here for radiological safety analysis; to verify that the dose acceptance criteria and safety goals are met with a high degree of confidence for dismantling of Tammuz-2 reactor core at Al-tuwaitha nuclear site. The activities characterizing, dismantling and packaging were practiced to manage the generated radioactive waste. Dose to the worker was considered an endpoint-scenario while dose to the public has neglected due to that Tammuz-2 facility is located in a restricted zone and 30m berm surrounded Al-tuwaitha site. Safety assessment for dismantling worker endpoint-scenario based on maximum external dose at component position level in the reactor pool and internal dose via airborne activity while, for characterizing and packaging worker endpoints scenarios have been done via external dose only because no evidence for airborne radioactivity hazards outside the reactor pool. The in-situ measurements approved that reactor core components are radiologically activated by Co-60 radioisotope. SAFRAN results showed that the maximum received dose for workers are (1.85, 0.64 and 1.3mSv/y) for activities dismantling, characterizing and packaging of reactor core components respectively. Hence, the radiological hazards remain below the low level hazard and within the acceptable annual dose for workers in radiation field

Probabilistic safety assessment (PSA) of a safety critical system: a case study of a nuclear power plant

Probabilistic Safety Assessment approach has been successfully applied in engineering, economics, computer science and statistics to re-solve a wide range of safety-related problems. However, using Probabilistic Safety Assessment for quantifying safety of a safety critical system is a challenging task in Safety Engineering community. This method plays an essential role in analyzing safety of safety critical sys-tems and its various components. Therefore, in this paper, we present Probabilistic Safety Assessment framework which can be used to quantify the critical failures of a systems. The approach is well demonstrated on a Digital Feed Water Control System uses in a Nuclear Power Plant as safety critical system.

Derivation of a speciic activity limit for plutonium for near surface disposal a case study at a potential site in northwest China

Based on the safety assessment framework and site-specific characteristic investigations in northwest China, an approach to deriving the specific activity limit of 239Pu is applied to establish a proposed value. Our analyses, in conjunction with the results of other previous studies, allow for the following conclusions: (1) As an intrusion scenario with a feature of minimal site-dependence and pervasive applicability, the drilling scenario can be used as the limiting scenario for the post-closure period; (2) Given a dose limit of 5 mSv per year, a derived specific activity of 287 Bqg-1 (at a disposal depth shallower than 5 m) for 239Pu is obtained through the formulation of models and subsequent calculations. It is suggested that both our approaches to deriving the limit and the results can be effectively applied to establish acceptance criteria of long-lived transuranic nuclides, for the particular disposal facility; and (3) From the standpoint of exploring the approach for limit derivation, the intrusion scenario and the corresponding exposure evaluation can be the focus of concern in the study area. It is implied that, in arid regions, a leaching scenario may lead to a more complex evaluation, with unnecessary effort, and can be virtually excluded.

Dynamic Safety Assessment in Nonlinear Hydropower Generation Systems

This paper focuses on the stability problems in a hydropower station. To enable this study, we consider a nonlinear hydropower generation system for the load rejection transient process based on an existing hydropower station. Herein we identify four critical variables of the generation system. Then, we carry out the dynamic safety assessment based on the Fisher discriminant method. The dynamic safety level of the system is determined, and the evolution behavior in the transient process is also performed. The result demonstrates that the hydropower generation system in this study case can operate safely, which is in a good agreement with the corresponding theory and actual engineering. Thus, the framework of dynamic safety assessment aiming at transient processes will not only provide the guidance for safe operation, but also supply the design standard for hydropower stations.

A heuristic framework for process safety assessment during research and development design stage

Process safety assessment is one of the most powerful approaches that can be used to communicate the strategies of hazard identification as well as risk assessment in the chemical process industry. Process safety has been introduced decades ago. Its importance and needs have become more obvious due to the constant increase of plant operation scales in the process industries. The increasing scale of process plant can be especially dangerous due to the presence of additional or higher magnitude of hazards. Between years 1996 and 2014, study shows that there are various methods that have been developed for the assessment of process safety including qualitative, quantitative as well as the combination of both. Despite the availability of an enormous number of methods, there is no detailed guideline on how to select which is the most suitable one that suits the scope, nature, interest and constraint of the assessment. This has led to slow adoption of detailed assessment (especially inherent safety) among industries, which based on the survey, have responded that too complicated methods have discouraged them from using the available methods. This is especially critical during the process design phase since not much information is already available. The best time to apply process hazard analysis is during research and development (R&D) design phase due to cost and time constraint. The main purpose of this study is to develop a framework for safety assessment in the R&D design phase of chemical processes. The framework was developed based on two aspects - (i) the methods screened to be suitable to be included in the framework and (ii) the specific stages in the design phase itself. This is important since different stage offers different type and amount of process information. Different method also requires a different type of information for the assessment. A simple case study is presented to demonstrate the application of the proposed framework.

The Research Framework for Quantitative Safety Assessment for Safety-Critical Computer Systems

Objectives: A safety-critical computer system has to be designed with safety in mind. The purpose of this paper is to identify and assess the safety hazards by using the proposed framework for Safety-Critical Computer Systems (SCCS). Methods/Statistical Analysis: Computer software quality models like McCall’s and Boehm’s were deficient in addressing the basic safety issues of SCCS. This paper proposes another safety model for software safety by adjusting McCall’s product quality model that particularly distinguishes the conditions comparing to software safety in safety-critical applications. The conditions in the proposed software safety model relate to Hazard Analysis distinguishing of Completeness of safety requirements, Safety-critical Design, Coding, and Testing. Findings: The criteria in the proposed software safety model relate to Hazard Analysis (HA) distinguishing of safety requirements, Completeness of safety requirements, Safety-critical Design, Safety-critical Coding, and Safety-critical Testing. The proposed safety model changes the current quality model by presenting different safety criteria’s and metrics in all phases of Software life cycle to assess the software safety. This model was connected to a safety basic Railroad Crossing Control System (RCCS) which is a laboratory prototype and obtained better results in terms of safety. Application/Improvements: This model was connected to a safety basic Railroad Crossing Control System (RCCS) which is a laboratory prototype and obtained better results in terms of safety.

Development of a Probabilistic Safety Assessment Framework for an Interim Dry Storage Facility Subjected to an Aircraft Crash Using Best-Estimate Structural Analysis

Using a probabilistic safety assessment, a risk evaluation framework for an aircraft crash into an interim spent fuel storage facility is presented. Damage evaluation of a detailed generic cask model in a simplified building structure under an aircraft impact is discussed through a numerical structural analysis and an analytical fragility assessment. Sequences of the impact scenario are shown in a developed event tree, with uncertainties considered in the impact analysis and failure probabilities calculated. To evaluate the influence of parameters relevant to design safety, risks are estimated for three specification levels of cask and storage facility structures. The proposed assessment procedure includes the determination of the loading parameters, reference impact scenario, structural response analyses of facility walls, cask containment, and fuel assemblies, and a radiological consequence analysis with dose–risk estimation. The risk results for the proposed scenario in this study are expected to be small relative to those of design basis accidents for best-estimated conservative values. The importance of this framework is seen in its flexibility to evaluate the capability of the facility to withstand an aircraft impact and in its ability to anticipate potential realistic risks; the framework also provides insight into epistemic uncertainty in the available data and into the sensitivity of the design parameters for future research.

Port Risk Management in Container Terminals

Abstract World trade increasingly relies on longer, larger and more complex port systems, where maritime transportation is a vital backbone of such operations. Port systems are more prone to being risk oriented. Many specific methods have been found to assess risk and safety in a port area or operation. A review is presented of different approaches to quantify the risk in port area. On the other hand, there is no specific risk management method or framework to cope with threats and hazards as a whole. This conceptual paper presents a Port Risk Management (PRM) methodology, seeking to transfer the safety-oriented Formal Safety Assessment (FSA) framework into the domain of port container terminal. The PRM methodology, has been developed to model all the probable port risks, by taking into account its different factors and their mutual influences. This paper presents a risk management methodology into the domain of port container terminals. This methodology constitutes a decision support framework that will be used to conduct port to port risk evaluations or to assess a whole port’s and terminal’s overall risk level in order to facilitate continues improvement strategies. An empirical study is contacted in order to provide evidence for risk management at the port container terminals in Greece. There is a need for methodologies and tools for assessing and managing the overall risk in maritime and port operations, which are increasingly complex and are dependable by systematic and nonsystematic risks. The critical impact on a number of port stakeholders has established a new methodology and a port risk index a considerable task.

Independent assessment for new nuclear reactor safety

A rigorous framework for safety assessment is established in all countries where nuclear technology is used for the production of electricity. On the one side, industry, i.e. reactor designers, vendors and utilities perform safety analysis and demonstrate consistency between results of safety analyses and requirements. On the other side, regulatory authorities perform independent assessment of safety and confirm the acceptability of safety of individual reactor units. The process of comparing results from analyses by reactor utilities and regulators is very complex. The process is also highly dependent upon mandatory approaches pursued for the analysis and from very many details which required the knowledge of sensitive proprietary data (e.g. spacer designs). Furthermore, all data available for the design, construction and operation of reactors produced by the nuclear industry are available to regulators. Two areas for improving the process of safety assessment for individual Nuclear Power Plant Units are identified: New details introduced by industry are not always and systematically requested by regulators for the independent assessment; New analytical techniques and capabilities are not necessarily used in the analyses by regulators (and by the industry). The established concept of independent assessment constitutes the way for improving the process of safety assessment. This is possible, or is largely facilitated, by the recent availability of the so-called Best Estimate Plus Uncertainty approach.

An overview on nature-inspired optimization algorithms for Structural Health Monitoring of historical buildings

Structural Health Monitoring (SHM) of historical building is an emerging field of research aimed at the development of strategies for on-line assessment of structural condition and identification of damage in the earliest stage. Built heritage is weak against operational and environmental condition and preservation must guarantee minimum repair and non-intrusiveness. SHM provides a cost-effective management and maintenance allowing prevention and prioritization of the interventions. Recently, in computer science, mimicking nature to address complex problems is becoming more frequent. Nature-inspired approaches turn out to be extremely efficient in facing optimization, commonly used to analyze engineering processes in SHM, providing interesting advantages when compared with classic methods. This paper begins with an introduction to Natural Computing. Then, focusing on its applications to SHM, possible improvements in built heritage conservation are shown and discussed suggesting a general framework for safety assessment and damage identification of existing structures.

Probabilistic-based assessment of a masonry arch bridge considering inferential procedures

Considering the safety assessment requirements of masonry arch bridges, different levels of reliability, based on uncertainty, may be distinguished, whose core objectives are to accurately analyse the ultimate load-carrying capacity and the serviceability structural response. Within this framework, a simplified full-probabilistic methodology for the safety assessment of existing masonry arch bridges is proposed, which combines both structural analysis and Bayesian inference procedures. The proposed framework aims to determine the ultimate load-carrying capacity (Ultimate Limit State) of masonry arch bridges, by using probabilistic procedures and Limit States principles. Geometric, material and load characterization, as well as inherent uncertainties will be also considered. In order to determine the ultimate load-carrying capacity, a limit analysis approach, based on the mechanism method, will be employed. Due to the high computational costs required by a probabilistic safety assessment framework, a sensitivity analysis will then be introduced. The incorporation of new information from monitoring and/or testing will be performed by the application of Bayesian inference methodologies. Based on the information collected, two reliability indexes will be computed and compared, one with data collected from design documentation and literature and the other with data collected from testing, emphasizing the importance of testing and the advantages of Bayesian inference procedures. The probabilistic framework developed is tested and validated in a Portuguese railway masonry arch bridge from the 19th century.

ENanoMapper – A database and ontology framework for design and safety assessment of nanomaterials

In this paper, we discuss the derivation of respiratory health effect factors (HEFs) for use in Life Cycle Impact Assessment (LCIA) for five nanoparticles: nanosilver, nano TiO2, carbon black, high-aspect ratio, rigid MWCNT and flexible MWCNT. For this purpose, we applied the methodology of USEtox™, a consensus model to calculate human toxicity and ecotoxicity characterization factors. In view of the available data, the non-carcinogenic HEFs for carbon black and TiO2 can be attributed the recommended status. For MWCNT and nanosilver the non-carcinogenic HEFs should be awarded the indicative status due to the minimal effects observed in the animal studies. All carcinogenic HEFs are currently labelled as indicative since there is no consensus with respect to the human relevance of the overload mechanism of carcinogenicity observed in rats exposed to poorly soluble particles (carbon black, flexible MWCNT and TiO2), whereas for high-aspect ratio, rigid MWCNT, the extrapolation from asbestos carcinogenicity introduces uncertainty. For nanosilver no carcinogenic HEF could be derived.The present study clearly demonstrates the difficulties associated with the derivation of HEFs for the nanomaterials considered, in particular in the USEtox™ framework for comparative risk assessment, and makes recommendations to overcome them:•Nanoparticles for which a dose metric other than its mass is relevant for their toxicity require ‘normalisation’ to the mass metric. Adaptation of USEtox™ to accommodate other dose metrics than mass intake is therefore recommended.•Simplified estimates of deposited and retained dose are currently needed, ignoring particle size distribution dependency. Therefore, it is recommended to include kg deposited and kg retained as dose parameters for HEFs in USEtox™ and to link USEtox™ to the Multiple Path Particle Dosimetry model to convert kg intake to these dose parameters.•Establishment of the Point of Departure (PoD) for the derivation of the HEFs and the extrapolation factors to be used is recommended through consensus building. Although the ED50 is preferred as the PoD from the perspective of comparative risk assessment in LCA, for some nanoparticles, other PoDs could be considered when the dose-response data are limited.•Overall, the assessed nanoparticles are likely to be more toxic than most bulk chemicals regarding non-carcinogenic effects. However, the results of LCIA based on these HEFs must be interpreted with the necessary constraints and reservations due to the large uncertainty involved.

Selection of maritime safety control options for NUC ships using a hybrid group decision-making approach

Maritime safety control is an essential step to mitigate risk in the well-known formal safety assessment framework. The selection of safety control options for NUC (not under control) ships is a challenge due to many influencing factors, together with the different preference formats on the attributes among the multiple involved organizations. This paper proposes a hybrid group decision-making approach to facilitate NUC ship safety control by incorporating fuzzy logic, consistency-based linear programming and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS). The kernel of the new method is to use fuzzy logic to obtain the attributes values by integrating the associated influencing factors, to employ consistency-based linear programming model to gain the interval weights of attributes, and to introduce TOPSIS for final decision-making. Consequently, this work provides a practical decision framework for NUC ship safety control.

A safety assessment framework for the Automatic Dependent Surveillance Broadcast (ADS-B) system

The ATM system is currently undergoing various fundamental changes to improve air travel performance. A key change is the transition from a mainly reactive and tactical system to a significantly more predictive and strategic system. This is encapsulated in the concept of 4D trajectory based operations, currently being developed in Europe and the USA through the Single European Sky (SES)/Single European Sky ATM Research (SESAR) and the Next Generation Air Transportation System (NextGEN) respectively. At the core of this transition, is the need for improved situational awareness, shared between relevant stakeholders. The Automatic Dependent Surveillance Broadcast (ADS-B) system is a key enabler of this concept, targeted at distributing real-time positioning and navigation information to stakeholders. Therefore, the safety and credibility of the ADS-B system to support various ground and airborne applications are key, and need to be assessed and validated. This paper reviews existing safety assessment methods, identifies key limitations and proposes a novel, comprehensive and rigorous safety assessment framework for the ADS-B system.

Safety assessment driving radioactive waste management solutions (sadrwms methodology) implemented in a software tool (safran)

In 2004, the International Atomic Energy Agency (IAEA) organized the International Project on Safety Assessment Driving Radioactive Waste Management Solutions (SADRWMS) to examine international approaches to safety assessment for predisposal management of radioactive waste. The initial outcome of the SADRWMS Project was achieved through the development of flowcharts which could be used to improve the mechanisms for applying safety assessment methodologies to predisposal management of radioactive waste. These flowcharts have since been incorporated into DS284 ( General Safety Guide on the Safety Case and Safety Assessment for Predisposal Management of Radioactive Waste), and were also considered during the early development stages of the Safety Assessment Framework (SAFRAN) Tool. In 2009 the IAEA presented DS284 to the IAEA Waste Safety Standards Committee, during which it was proposed that the graded approach to safety case and safety assessment be illustrated through the development of Safety Reports for representative predisposal radioactive waste management facilities and activities. To oversee the development of these reports, it was agreed to establish the International Project on Complementary Safety Reports: Development and Application to Waste Management Facilities (CRAFT). The goal of the CRAFT project is to develop complementary reports by 2014, which the IAEA could then publish as IAEA Safety Reports. The present work describes how the DS284 methodology and SAFRAN Tool can be applied in the development and review of the safety case and safety assessment to a range of predisposal waste management facilities or activities within the Region.

Development and evaluation of an enhanced surrogate safety assessment framework

This study adopted an integrated simulation approach for generating more realistic vehicle trajectories, ultimately for enhancing the surrogate safety assessment methodology under the Connected Vehicle (CV) environment. This integrated simulation divides into two main parts, real time-based simulation approach and post-processing approach. The real-time simulation environment consists of the microscopic traffic simulator to generate various traffic situations, driver warning simulator, GPS/INU simulator, and V2V/V2I communication delays probability model. The post-processing approach includes vehicle dynamics model to incorporate vehicle dynamics to the vehicle trajectories and Surrogate Safety Assessment Model (SSAM) to identify traffic conflicts. This integrated simulation approach was adopted to assess the safety impact of Connected Vehicle (CV)-based traffic applications by considering potential positioning errors and communication delays which are likely to occur in reality. The evaluation results showed that the V2V/V2I communication delays degraded the effectiveness of driver warnings by 3–13% while the driver warnings under ideal conditions (i.e., error-free vehicle positions and no V2V/V2I communication delays) reduced conflicts by 27–42%. In addition, the most accurate GPS/INU device (i.e., Real-Time Kinematic (RTK) GPS) was the best for use with vehicle safety applications as the RTK case was the closest to the ground truth-based warning scenario. Meanwhile, the device with the lowest accuracy (i.e., autonomous GPS) was not very suitable for deployment in the safety application as this case showed even worse results than the base case (i.e., no driver warnings). This integrated simulation approach used for these experiments is a practical and reliable alternative for assessing the safety impact of CV-based traffic applications since it considers the potential positioning errors and communication delays which are likely to affect the performance of CV-based traffic applications in reality and uses vehicle dynamics-incorporated vehicle trajectories which are more realistic than the sore traffic simulator vehicle trajectories.

The interim regulated legal market for NPS ('legal high') products in New Zealand: The impact of new retail restrictions and product licensing.

New Zealand has recently established the world's first regulated legal market for new psychoactive products (NPS) (i.e. 'legal highs'). While the new regime is currently in a transitional phase, a range of retail restrictions and an interim licensing regime for NPS products and operators has been introduced. A product safety assessment framework has been developed to determine if a product should receive an interim licence. As a result of the licensing requirements, the number of NPS retail outlets fell from 3000- 4000 largely convenience stores to 156 specialty stores, and the number of legally available NPS products fell from 200 to fewer than 46. Some of the licensed products contain potent cannabinoid compounds. The licensing system provided, for the first time, information on all the products and operators involved in the sector, and this will assist future monitoring. The effectiveness of the new product safety assessment framework will depend on the quality of the data available on adverse cases. This is a challenge as self-reported information from users is often unreliable, and some emergency department cases do not have all the information required to make an accurate assessment. These data limitations indicate the need for retrospective studies of NPS adverse cases and additional test data. While the new legislation initially reduced the number of NPS retailers by prohibiting convenience outlets, new specialized NPS retail outlets may emerge as the new sector expands. Empirical research is required to measure the impact of the reduction in retail outlets and products on NPS availability.

Expectation-Maximization Algorithm Embedded Framework for Safety Assessment of Reinforced Concrete Systems

This paper studies the safety assessment of in-service reinforced concrete (RC) structures with incomplete appraisal data. An appraisal data missingness event may occur under a series of circumstances, such as the breakdown of the data acquisition system involved. To deal with the incomplete appraisal data, two straightforward options—that is, pairwise and listwise parameter estimation schemes—are first explored, and the discussion focuses on the positive-semidefiniteness criterion, the additional information loss, and the probability of noninformativeness. An expectation-maximization (EM) algorithm embedded safety assessment framework for in-service RC systems is then formulated as a remedy for the missingness of the appraisal data. Through a designed statistical hypothesis testing scheme, the efficacy and the general applicability of the framework are illustrated using both the numerically simulated appraisal data and the data collected by a rebound hammer during a field investigation. The proposed framework has the potential to be incorporated into the sustainable RC structural design paradigms.

On a systematic perspective on risk for formal safety assessment (FSA)

In the maritime domain, risk is evaluated within the framework of the Formal Safety Assessment (FSA), introduced by the International Maritime Organization in 2002. Although the FSA has become an internationally recognized and recommended method, the definition, which is adopted there, to describe the risk, seems to be too narrow to reflect the actual content of the FSA.Therefore this article discusses methodological requirements for the risk perspective, which is appropriate for risk management in the maritime domain with special attention to maritime transportation systems. A perspective that is proposed here considers risk as a set encompassing the following: a set of plausible scenarios leading to an accident, the likelihoods of unwanted events within the scenarios, the consequences of the events and description of uncertainty. All these elements are conditional upon the available knowledge (K) about the analyzed system and understanding (N) of the system behavior. Therefore, the quality of K and the level of N of a risk model should be reflected in the uncertainty description. For this purpose we introduce a qualitative scoring system, and we show its applicability on an exemplary risk model for a RoPax ship.