Safety Case Research Articles

Impact of the heterogeneity of the sandy Opalinus clay facies at the Mont Terri underground research laboratory on radionuclide migration

Abstract. The assessment of the safety of a deep geological repository (DGR) for high-level radioactive wastes over assessment time scales of up to 1 million years requires an in-depth understanding of the multi-scale coupled processes that affect the repository system evolution over time, to reduce uncertainties and conservatism in safety analyses. This is in particular required with respect to the challenges of a comparative assessment of different repository concepts in different host rocks within the process of a site selection for a DGR for heat-generating radioactive wastes in Germany. The collaborative project “Integrity of nuclear waste repository systems – Cross-scale system understanding and analysis (iCross)” conducted jointly by five research centres of the Helmholtz Association and co-funded by the Initiative and Networking Fund of the Helmholtz Association and the Federal Ministry of Education and Research (BMBF) has been initiated with the overall objective to improve the understanding of coupled thermal-hydraulic-mechanical-chemical-(micro)biological (THMCB) processes and to develop simulation tools that enable a holistic close to reality description of the long-term evolution of the repository system. Geological formations, such as those foreseen as potential host rocks for DGRs, and their surroundings are heterogeneous on various length scales ranging from nanometers to kilometers. Therefore, the aim of this work in the context of iCross is to evaluate the effects of mineralogical, geochemical and microstructural heterogeneities of repository host rocks on radionuclide transport in the repository far field, using the sandy facies of the Opalinus clay (SF-OPA) from the Mont Terri underground research laboratory (St. Ursanne, Switzerland) as an example. Here, we address in particular the migration behaviour of Ra-226 as an important radionuclide to be considered in safety cases for deep geological disposal of spent nuclear fuel. To assess the impact of the heterogeneities in SF-OPA on radionuclide transport, a complementary approach combining microstructural characterisation methods, experimental techniques for the determination of transport parameters of the rock matrix and the mobility of Ra-226 with innovative developments in reactive transport modelling on the pore and continuum scales was pursued. One of the results was that although the limited clay content in SF-OPA decreases the total amount of Ra bound to the illite phase, the solid solutions of sulphate and carbonate compensate for this and provide a major fixation mechanism.

Advanced gas-cooled reactors technology for enabling molten-salt reactors design – Optimisation of a new system

Molten salts present significant advantages as coolants over traditional light water or gas. Salt-cooled nuclear reactor can potentially i allow an increase in core power density and simplify the reactor safety case. Traditionally, molten salt reactors assume molten salt being both the fuel and the coolant. This, however, creates major challenges for the design and operation due to requirements for chemistry control and corrosion behaviour of the core structural materials. The Fluoride salt-cooled High-temperature Reactors (FHR) on the other hand, have conventional solid fuel geometry surrounded by moderator and coolant. Furthermore, some FHR variations share many common characteristics with the Advanced Gas-cooled Reactors (AGR). Thus, using the knowledge accumulated during many decades of successful AGR operation can speed up the FHR development and deployment. However, replacing carbon-dioxide coolant by molten salt significantly changes the reactor performance. Hence, a new core design is needed. In this work, a Multi-Objective Particle Swarm Optimisation is used to identify the most favourable configurations for a new system layout. Initially, the optimisation targeted the beginning of cycle parameters such as criticality and Coolant Temperature Coefficient (CTC). The present work is the next step in this analysis. Each configuration is examined with respect to its thermal-hydraulic performance to assess the power uprate potential which is limited by multiple temperature constraints (e.g. fuel centreline and cladding temperatures as well as the coolant freezing/boiling). The estimated maximum power was then used in the fuel burnup calculations, from which a discharge burnup and cycle average CTC were obtained. As a result of the optimisation process, several families of possible solutions were identified, which form an optimal Pareto front. The most attractive configurations in terms of achievable power density, however, were not necessarily on the Pareto front. Most of the identified design options had only a small amount of graphite moderator or no graphite at all, relying entirely on moderation in the salt. Increasing the graphite volume was consistently found to worsen most of the optimisation parameters. The newly identified design options have the potential to achieve power density which is higher than that of a typical AGR by up to a factor of five, while maintaining negative CTC through the burnup cycle.

1141 Robotic Assisted Surgery in Horseshoe Kidneys: A Safety and Feasibility Multicentre Case Series

Abstract Introduction Horseshoe kidneys (HSK) are the most common renal fusion abnormality. However, they are only present in 0.2% of the population. Due to anatomical variation in vasculature, ectopia and malrotation, surgery has traditionally been performed via an open approach. We aimed to assess the safety and feasibility of robot-assisted surgery for HSK. Method Six patients (four female, two male) with HSKs were operated on between 2016 and 2019 across two high-volume centres by high-volume surgeons. All operations were robot-assisted, with three partial nephrectomies and one nephroureterectomy for renal masses and two benign nephrectomies for non-functioning kidneys. 3D reconstruction using CT renal angiograms was used to help identify vasculature and tumour location (where appropriate). Results The median age was 53 years (IQR 47-58.3) and the median BMI was 25 (IQR 25-25.8). Median tumour size in the four patients with renal masses was 35.5 mm (IQR 25.3-44.8). Median console time was 120 minutes (IQR 117-172.5) and the median estimated blood loss was 150 mL (IQR 112.5-262.5). The median pre-operative eGFR was 76 (IQR 70-86.5) and median post-operative eGFR was 65.5 (IQR 59.3-80.8). All operations were uneventful, there were no perioperative transfusions and no complications reported. Length of stay was two days for all patients. Conclusions We report the largest series of mixed robotic-assisted surgery on HSK. Robotic surgery is safe and feasible for HSK in high-volume centres with acceptable perioperative outcomes. Further prospective, longer-term, multi-centre studies are required to evaluative if robotic surgery for HSK is superior to open surgery.

Use of a Rubric to Improve the Quality of Internal Medicine Resident Event Reporting.

IntroductionAs frontline providers, residents report patient safety events and provide crucial safety feedback. Specific ACGME and AAMC requirements for graduating residents include active participation in event reporting and patient safety investigations. However, formal training on what information a quality event report should include to effect real change in the health care system is lacking.MethodsThis practical, interactive, case-based workshop educates residents on the key components of a quality event report in a 1-hour time frame. The scoring rubric offers quantitative feedback on the quality of information provided in residents’ own event reports. The materials include a presentation template, sample teaching points, pre- and posttraining patient safety cases for residents to complete their own event reports about, and a standardized rubric to score event reports for feedback.ResultsDuring the fall of 2019, 198 internal medicine residents completed the workshop, and 143 matched pre- and postcourse surveys were reviewed. Residents’ ability to correctly identify the key concepts of an event report improved from a median score of 4 to 8 (p < .001). After completion of training, residents reported increased knowledge regarding the content of an effective event report (p < .001) and increased confidence in their ability to write one (p < .001).DiscussionResidents’ knowledge of key event-reporting concepts and confidence in reporting improved after completion of the workshop. This brief interactive training and its novel rubric can be used as a standardized tool for patient safety curricula in academic training programs.

Model-based safety engineering for autonomous train map

As a part of the digital revolution of railway systems, an autonomous driving train will use a complete and precise map of railway infrastructure to conduct operational actions. Nevertheless, the full autonomy of trains depends on the safety decisions management capacity both on-board and track-side. These decisions must be refined into safety requirements in order to continuously check the consistency between the perceived infrastructure and safety related properties. However, traditionally, the integration of safety analysis requires the intervention of human agent skills. This may be error-prone and in interference with the embedded aspect of the train map. In this paper, we propose a model-based approach to match between safety concepts expressed as an ontology, a derived safety model and a safety-extended railway infrastructure map model for autonomous trains. This approach is validated by railway safety case studies for autonomous train map. The integration of this model-based safety solution from the early stages of the map system design improves the safety decisions management process.

Temperature dependent lithium isotope fractionation during glass dissolution

Understanding the mechanisms by which borosilicate glasses corrode in contact with aqueous solutions remains a challenge to the safety case for the geological disposal of vitrified high-level nuclear waste. Here, lithium isotope fingerprinting techniques were applied to the leachates of a simulant Magnox waste glass to probe the mechanisms of aqueous corrosion at both short and long timescales (6 hours to 464 days). Experiments took place at 40 and 90 °C to assess the consistency of the dissolution mechanisms across a range of commonly employed temperatures and the legitimacy of applying higher temperature experimental datasets to understand glass corrosion within a disposal facility at lower temperatures.Two competing release mechanisms were observed for lithium (diffusion and hydrolysis), and the relative proportions of these mechanisms changed through time. Leachates initially had lower δ7Li values than the pristine glass (−2.7‰ at 40 °C and −1.1‰ at 90 °C relative to the pristine glass) at both temperatures due to lithium leaching incongruently through diffusive processes. The greater offset between solution and solid at lower temperatures indicates a larger rate of diffusion (incongruent dissolution) relative to the rate of hydrolysis (congruent dissolution) at lower temperatures. The fraction of lithium released through diffusion relative to the fraction of lithium released through hydrolysis then increased at both temperatures with time up to 126 days, increasing from 0.47 and 0.22 at 6 hours to 0.66 and 0.41 at 126 days at 40 and 90 °C respectively. Subsequently, the fractions of lithium released through diffusion sharply decreased to 0.36 at 40 °C and 0.22 at 90 °C after 464 days, consistent with network hydrolysis coupled with secondary phase precipitation later controlling the long-term release of Li at both temperatures. Throughout the duration of the experiments (464 days) the δ7Li values in solution increased to 9.0‰ at 40 °C and 10.0‰ at 90 °C due to the formation of talc and montmorillonite phases at 40 °C and additional smectite phases at 90 °C. Further, no evidence for the formation of a diffusive barrier to the transport of Li within the alteration layers became apparent during the later stages of dissolution at either temperature. However, the fraction of lithium leached through diffusion was still significant throughout all stages of dissolution. Lithium isotope ratios in solution were correlated with the transition from a system which was increasingly dominated by lithium diffusion as the dissolution rate slowed to one which was controlled by hydrolysis coupled with secondary phase precipitation at long durations. Alongside elemental ratios in solution, these results were consistent with the same set of mechanisms governing dissolution across the temperature range studied.

Agents that Argue and Explain Classifications of Retinal Conditions

PurposeExpertise for auditing AI systems in medical domain is only now being accumulated. Conformity assessment procedures will require AI systems: (1) to be transparent, (2) not to rely decisions solely on algorithms, or (3) to include safety assurance cases in the documentation to facilitate technical audit. We are interested here in obtaining transparency in the case of machine learning (ML) applied to classification of retina conditions. High performance metrics achieved using ML has become common practice. However, in the medical domain, algorithmic decisions need to be sustained by explanations. We aim at building a support tool for ophthalmologists able to: (i) explain algorithmic decision to the human agent by automatically extracting rules from the ML learned models; (ii) include the ophthalmologist in the loop by formalising expert rules and including the expert knowledge in the argumentation machinery; (iii) build safety cases by creating assurance argument patterns for each diagnosis.MethodsFor the learning task, we used a dataset consisting of 699 OCT images: 126 Normal class, 210 with Diabetic Retinopathy (DR) and 363 with Age Related Macular Degeneration (AMD). The dataset contains patients from the Ophthalmology Department of the County Emergency Hospital of Cluj-Napoca. All ethical norms and procedures, including anonymisation, have been performed. We applied three machine learning algorithms: decision tree (DT), support vector machine (SVM) and artificial neural network (ANN). For each algorithm we automatically extract diagnosis rules. For formalising expert knowledge, we relied on the normative dataset (Invernizzi et al. in Ophthalmol Retina 2(8):808–815, 2018). For arguing between agents, we used the Jason multi-agent platform. We assume different knowledge base and reasoning capabilities for each agent. The agents have their own optical coherence tomography (OCT) images on which they apply a distinct machine learning algorithm. The learned model is used to extract diagnosis rules. With distinct learned rules, the agents engage in an argumentative process. The resolution of the debate outputs a diagnosis that is then explained to the ophthalmologist, by means of assurance cases.ResultsFor diagnosing the retina condition, our AI solution deals with the following three issues: first, the learned models are automatically translated into rules. These rules are then used to build an explanation by tracing the reasoning chain supporting the diagnosis. Hence, the proposed AI solution complies with the requirement that “algorithmic decision should be explained to the human agent”. Second, the decision is not solely based on ML-algorithms. The proposed architecture includes expert knowledge. The diagnosis is taken based on exchanging arguments between ML-based algorithms and expert knowledge. The conflict resolution among arguments is verbalised, so that the ophthalmologist can supervise the diagnosis. Third, the assurance cases are generated to facilitate technical audit. The assurance cases structure the evidence among various safety goals such as: machine learning methodology, transparency, or data quality. For each dimension, the auditor can check the provided evidence against the current best practices or safety standards.ConclusionWe developed a multi-agent system for retina conditions in which algorithmic decisions are sustained by explanations. The proposed tool goes behind most software in medical domain that focuses only on performance metrics. Our approach helps the technical auditor to approve software in the medical domain. Interleaving knowledge extracted from ML-models with expert knowledge is a step towards balancing the benefits of ML with explainability, aiming at engineering reliable medical applications.

Preliminary study of patient safety and quality use cases for ICD-11 MMS.

This study investigated how well-suited the International Classification of Diseases, 11th Revision, for Mortality and Morbidity Statistics, (ICD-11 MMS) is for 2 morbidity use cases, patient safety and quality, examining the level of detail captured, and evaluating the necessity for the development of a US clinical modification (CM). Utilizing the 5 NCVHS-specified perspectives plus the consumer perspective, a framework was created of International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) use cases. Analysis yielded candidate source criteria for use in case evaluation. Patient safety and quality were chosen because they are relevant across all perspectives.Granularity differences and content coverage of ICD-11 MMS entities were assessed pre- and post-coordination to determine suitability for the 2 use cases. Pressure ulcers, a common condition across 3 patient safety applications, became the focus for comparing ICD-10-CM codes to ICD-11 MMS codes. For 3 electronic clinical quality measures (eCQMs), the evaluation centered on specified value sets for ischemic stroke, hypertension, and diabetes. For pressure ulcers, the ICD-11 MMS was found to exceed ICD-10-CM capabilities via post-coordinated extension codes. For the 3 eCQM value sets explored, the ICD-11 MMS fully represented the disease concepts when post-coordinated code clusters were used. The examples from the patient safety and quality use cases evaluated in this study are appropriate for ICD-11 MMS. It captures greater detail than ICD-10-CM, and ICD-11 MMS specificity would benefit both use cases. The authors believe this preliminary study indicates the US should invest resources to explore adopting the WHO ICD-11 MMS and tooling and guidelines to implement post-coordination.

Life-Extension Project Applies Assessment of Reinforced Concrete to Nonjacket Structures

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 31250, “Wandoo B: Application of Advanced Reinforced Concrete Assessment for Life Extension for Non-Jacket Structures,” by Robert Sheppard, Spire Engineering; Colin O’Brien, Vermilion Oil and Gas; and Yashar Moslehy, Spire Engineering, et al., prepared for the 2021 Offshore Technology Conference, originally scheduled to be held in Houston, 4–7 May. The paper has not been peer reviewed. Copyright 2021 Offshore Technology Conference. Reproduced by permission. Wandoo B is a concrete gravity-based structure (GBS) and is the main production facility for the Wandoo field offshore northwest Australia. It was installed in 1997 with a design life of 20 years. The structural assessments discussed in this paper are part of a comprehensive life-extension project encompassing wells, subsea systems, marine and safety systems, and topsides facilities and structures to demonstrate fitness for service through the end of field life. Background The GBS serves as the support structure for the Wandoo B facility and provides oil storage for the Wandoo field. The structure has four shafts approximately 11 m in diameter that support the top-sides facilities and a base structure with permanent ballast and oil storage cells (Fig. 1). It was originally developed as an ExxonMobil-led project and now is owned and operated wholly by Vermilion Oil and Gas Australia. The reinforced concrete (RC) shafts and the base top slab are pretensioned. In the shafts, tendons are enclosed in 20 ducts distributed around the circumference. The top of the shafts provides a mating point with the steel topsides structure with the connection formed by embedded anchor bolts in a bulge in the shaft cross section. The topsides structure is a three-level braced steel frame system supporting production operations for 12 well conductors contained within the northeast shaft and three outboard well conductors. Life-Extension Project The facility was designed with a target life of 20 years. The life-extension project was intended not only to satisfy the operator’s responsibility to continue safe operations and adhere to their safety case but also to meet the expectations of the regulator. The structural aspects of the project included four phases, the first two of which are detailed in this synopsis: - Design assessments per latest standards and modifications where required - Ultimate capacity assessments with retrofit modifications where required - Risk studies and workshops to demonstrate that risk is as low as reasonably practicable (ALARP) - Integrity-management manual and inspection plan The first two phases were addressed using the latest condition-assessment, weight, and environmental data available. The phased approach allowed the assessment team to use basic linear approaches to demonstrate code compliance and only use the more-advanced analysis techniques to evaluate the critical components that did not satisfy code or were needed to provide input to the ALARP assessment and establish target reliability for the facility.

Study on the Interference Process of Liquid Radial Reflux on the Stability of a Shaped Charge Jet

The process of liquid radial reflux interference during jet penetration in a liquid-filled composite structure is divided in this study into three stages: bottom plate reflection interference, side-wall reflection interference, and side-wall secondary reflection interference. The calculation model of the velocity interval of the disturbed jet and the residual penetration depth of the jet has been established through theoretical analysis. Results show that the liquid-filled composite structure can interfere with the high-speed section of the shaped charge jet. The accuracy of the theoretical analysis in this paper has been verified through numerical simulation, X-ray, and depth-of-penetration experiments. Among the results, those of the X-ray experiment show that the liquid-filled composite structure has interference on the tip of the shaped charge jet, which provides a possibility for the application of the liquid-filled composite structure to ammunition safety and other extreme cases.

Variability of Gravel Pavement Roughness: An Analysis of the Impact on Vehicle Dynamic Response and Driving Comfort

Gravel pavement has lower construction costs but poorer performance than asphalt surfaces on roads. It also emits dust and deforms under the impact of vehicle loads and ambient air factors; the resulting ripples and ruts constantly deepen, and therefore increase vehicle vibrations and fuel consumption, and reduce safe driving speed and comfort. In this study, existing pavement quality evaluation indexes are analysed, and a methodology for adapting them for roads with gravel pavement is proposed. We report the measured wave depth and length of gravel pavement profile using the straightedge method on a 160 m long road section at three stages of road utilization. The measured pavement elevation was processed according to ISO 8608, and the frequency response of a vehicle was investigated using simulations in MATLAB/Simulink. The international roughness index (IRI) analysis showed that a speed of 30–45 km/h instead of 80 km/h provided the objective results of the IRI calculation on the flexible pavement due to the decreasing velocity of a vehicle’s unsprung mass on a more deteriorated road pavement state. The influence of the corrugation phenomenon of gravel pavement was explored, identifying specific driving safety and comfort cases. Finally, an increase in the dynamic load coefficient (DLC) at a low speed of 30 km/h on the most deteriorated pavement and a high speed of 90 km/h on the middle-quality pavement demonstrated the demand for timely gravel pavement maintenance and the complicated prediction of a safe driving speed for drivers. The main relevant objectives of this study are the adaptation of a road roughness indicator to gravel pavement, including the evaluation of vehicle dynamic responses at different speeds and pavement deterioration states.

A sensitivity study of the factors affecting the risks associated with the disposal of spent nuclear fuel in a geological disposal facility in a clay environment

The disposal route for the UK's inventory of spent nuclear fuel has yet to be decided upon, however if the UK follows the approach taken by many nations, its spent nuclear fuel will be destined for geological disposal. This paper provides a simplified, approach to the calculation of radiological risk posed to members of the public, associated with the disposal of spent advanced gas-cooled reactor (AGR) nuclear fuel in a geological disposal facility (GDF) located in a hypothetical clay geological setting. Simulating the release of radionuclides at differing levels of complexity shall aid in the development of aspects of the design, construction, operation, decommissioning and post-closure phases of geological disposal and the development of a safety case for geological disposal. This paper presents a high-level, 1-D model built in GoldSim, to provide an initial indication of the radiological risks to the public, the nature of which would require further development into a complex total system model in order to facilitate risk evaluation supplementary to a safety case. The model was validated against benchmark calculations provided by Radioactive Waste Management Ltd. The base case calculations suggest that the predicted risks to the potential exposed groups are well below, approximately 2 orders, the recommended risk guidance level of 1 × 10−6 per year. A number of sensitivity studies were carried out to identify the importance of various factors that could influence the predicted risks. Sensitivity analysis indicated that the most influential sensitivities on the annual risk posed by geological disposal were the depth and rate at which spent nuclear fuel dissolved in contact with groundwater. The pathways available for groundwater flow to the biosphere were also noted to significantly alter the peak risk observed; crucially almost all sensitivities did not increase the peak risk to within 1 order of magnitude below the recommended risk guidance level. Validation for a second hypothetical high strength rock geological setting resulted in higher projected predicted risks to the potential exposed groups although risk levels remained below the recommended risk guidance level. This suggests a clay environment may have favourable characteristics for the final disposal of spent nuclear fuel compared to a high strength rock alternative.

The Role of Construal Alignment in Enterprise Risk Management

ABSTRACT According to the Committee of Sponsoring Organizations of the Treadway Commission (COSO 2017), two important elements of an organization's enterprise risk management (ERM) framework are its risk management philosophy, and its risk appetite and tolerance. Based on Construal Level Theory (CLT), we posit that the effectiveness of ERM depends on the extent of alignment (non-fit or fit) between mental representations (high versus low construal) of those two ERM elements. We test our hypothesis across two risk cases: safety and confidentiality. Results of our experiment suggest that employees are more proactive when there is a construal fit between the emphasis placed on a firm's risk management philosophy and its expression of the key risk indicators (KRIs). This benefit is observed in the confidentiality case, but not in the safety case. Implications are discussed.

Supplemental Material for Testing Boundary Conditions in the Communication–Cohesion Relationship in Team Sport: The Case for Psychological Safety

Supplemental Material for Testing Boundary Conditions in the Communication–Cohesion Relationship in Team Sport: The Case for Psychological Safety

Communication, information, and education (CIE) on food safety issues in Kalimojosari Village, Pekalongan

Food safety issues in Indonesia are still a common concern. Lack of knowledge causes the number of food safety cases is increasing, such as snack poisoning and diarrhea. This community service was carried out to form the PKK Food Safety Cadre in Kalimojosari Village which is expected to provide information and education to local residents regarding food safety. The implementation method applied was communication, information, and education counseling through the lecture method. The result of this community service activity is an increase in knowledge about food safety issues by 6.08%.

A dual porosity poroelastic model for simulation of gas flow in saturated claystone as a potential host rock for deep geological repositories

Claystone is considered as a potential host rock for radioactive waste disposal at great depth in many countries. Considerable quantity of gas can be generated in a deep geological repository (DGR) due to several processes, which may affect the integrity of the host rock and the safety of the DGR. Thus, understanding the migration of gas through the host rock is an essential requirement in developing a safety case for a deep geological disposal of radioactive waste. In this paper, a fully coupled dual porosity poroelastic model is developed to simulate the gas transport process in initially saturated claystone. The model considers the hydro-mechanical behavior for the fractured porous medium consisting of both the porous matrix (represented by the porous continuum) and fractures (represented by the fractured continuum), which are two separate and overlapping porous media. Each continuum has its own constitutive law that imposes a superimposed effect on the behavior of the fractured porous medium. The mechanical coupling between the two continua is through total stress equilibrium and strain superimposition technique, while the fluid coupling in the two continua is through water exchange term and porosity interaction. The capability of the developed dual porosity poroelastic model is evaluated by comparing the simulated results with that recorded in the laboratory gas injection tests on claystone, in which the main experimental behaviors, i.e., the major gas breakthrough, sample volume dilation, gas induced fracturing are well represented.

Cost Benefit Analysis of Implementation Occupational Health and Safety: Literature Review

Assessment of management commitments is required for investment in Occupational health and safety program. This systemic literature review evaluates 15 cases of Occupational health and safety (OHS) interventions to assess whether the implementation of OHS is beneficial. Search engines used in literature review are Medline, Embase, Web of Science, Cochrane Library, Pubmed. Studies related to benefit cost analysis included in the search include also looking at company productivity. The focus of this analysis includes samples, design, theoretical framework, implementation OHS, validity and results.Results show,in 15 cases, cross-sectional research design looked at pre-after comparisons in the absence of control groups. The positive return on investment from the implementation of OHS is shown in 13 studies. Two other studies concluded that their chosen implementation of OHSwas not cost-effective. The main benefit is to reduce sick leave. In 3 cases the perceived benefit is an increase in productivity and quality. The conclusions in this study required a guideline for the evaluation of the implementation of OHS.

What difference has the Cullen Report made? Empirical analysis of offshore safety regulations in the United Kingdom's oil and gas industry

Anecdotal evidence from the United Kingdom's offshore oil and gas industry indicates that risk-based safety regulations, introduced in the aftermath of the 1988 Piper Alpha disaster which killed 167 offshore workers, have improved safety outcomes such as reducing fatalities and dangerous occurrences. However, the empirical dimensions of this supposed improved safety record in the literature is scanty. This paper explores the relationship between the safety regulatory regime and safety outcomes in the UK offshore oil and gas industry from 1995 to 2011 using multivariate regression analysis based on the generalized linear modelling framework. We assess the trend and impact of the regulatory changes implemented through the safety case regulations on major hazard risk indicators such as hydrocarbon releases controlling for technical factors such as type of offshore facility, facility location, water depth, production levels, and external factors such as oil prices, acting as a measure of the prevailing macroeconomic activity level. The results show a statistically significant industry-wide decline in hydrocarbon releases between 1995 and 2011 (average marginal effects), after controlling for location, water depth, installation type, installation age and other factors. This reflects both the commitment of operating companies and the regulator to reducing major accident hazards in line with the principles underlying the safety case regime. Other offshore jurisdictions could focus major accident reduction efforts predicated on goal-setting safety case principles which identify key safety-critical elements of an oil and gas installation and put in place risk-based mitigation measures.

Design and Calibration of a Hall Effect System for Measurement of Six-Degree-of-Freedom Motion within a Stacked Column.

This paper presents the design, development and evaluation of a unique non-contact instrumentation system that can accurately measure the interface displacement between two rigid components in six degrees of freedom. The system was developed to allow measurement of the relative displacements between interfaces within a stacked column of brick-like components, with an accuracy of 0.05 mm and 0.1 degrees. The columns comprised up to 14 components, with each component being a scale model of a graphite brick within an Advanced Gas-cooled Reactor core. A set of 585 of these columns makes up the Multi Layer Array, which was designed to investigate the response of the reactor core to seismic inputs, with excitation levels up to 1 g from 0 to 100 Hz. The nature of the application required a compact and robust design capable of accurately recording fully coupled motion in all six degrees of freedom during dynamic testing. The novel design implemented 12 Hall effect sensors with a calibration procedure based on system identification techniques. The measurement uncertainty was ±0.050 mm for displacement and ±0.052 degrees for rotation, and the system can tolerate loss of data from two sensors with the uncertainly increasing to only 0.061 mm in translation and 0.088 degrees in rotation. The system has been deployed in a research programme that has enabled EDF to present seismic safety cases to the Office for Nuclear Regulation, resulting in life extension approvals for several reactors. The measurement system developed could be readily applied to other situations where the imposed level of stress at the interface causes negligible material strain, and accurate non-contact six-degree-of-freedom interface measurement is required.

Security assurance cases\u2014state of the art of an emerging approach

Security Assurance Cases (SAC) are a form of structured argumentation used to reason about the security properties of a system. After the successful adoption of assurance cases for safety, SAC are getting significant traction in recent years, especially in safety-critical industries (e.g., automotive), where there is an increasing pressure to be compliant with several security standards and regulations. Accordingly, research in the field of SAC has flourished in the past decade, with different approaches being investigated. In an effort to systematize this active field of research, we conducted a systematic literature review (SLR) of the existing academic studies on SAC. Our review resulted in an in-depth analysis and comparison of 51 papers. Our results indicate that, while there are numerous papers discussing the importance of SAC and their usage scenarios, the literature is still immature with respect to concrete support for practitioners on how to build and maintain a SAC. More importantly, even though some methodologies are available, their validation and tool support is still lacking.