Managing technology development for safety-critical systems

This paper presents a model that determines the optimal budget allocation strategy for the development of new technologies for safety-critical systems over multiple decision periods. The case of the development of a hypersonic passenger airplane is used as an illustration. The model takes into account both the probability of technology development success as a function of the allocated budget, and the probability of operational performance of the final system. It assumes that the strategy is to consider (and possibly fund) several approaches to the development of each technology to maximize the probability of development success. The model thus decomposes the system's development process into multiple technology development modules (one for each technology needed), each involving a number of alternative projects. There is a tradeoff between development speed and operational reliability when the budget must be allocated among alternative technology projects with different probabilities of development success and operational reliability (e.g., an easily and quickly developed technology may have little robustness). The probabilities of development and operational failures are balanced by a risk analysis approach which allows the decision maker to optimize the budget allocation among different projects in the development program at the beginning of each budget period. The model indicates that by considering reliability in the R&D management process, the decision maker can make better decisions, optimizing the balance between development time, cost, and robustness of safety-critical systems.Technology development; system reliability; risk analysis; project management

Human Error Analysis in a Permit to Work System: A Case Study in a Chemical Plant.

BACKGROUND: A permit to work (PTW) is a formal written system to control certain types of work which are identified as potentially hazardous. However, human error in PTW processes can lead to an accident. METHODS: This cross-sectional, descriptive study was conducted to estimate the probability of human errors in PTW processes in a chemical plant in Iran. In the first stage, through interviewing the personnel and studying the procedure in the plant, the PTW process was analyzed using the hierarchical task analysis technique. In doing so, PTW was considered as a goal and detailed tasks to achieve the goal were analyzed. In the next step, the standardized plant analysis risk-human (SPAR-H) reliability analysis method was applied for estimation of human error probability. RESULTS: The mean probability of human error in the PTW system was estimated to be 0.11. The highest probability of human error in the PTW process was related to flammable gas testing (50.7%). CONCLUSION: The SPAR-H method applied in this study could analyze and quantify the potential human errors and extract the required measures for reducing the error probabilities in PTW system. Some suggestions to reduce the likelihood of errors, especially in the field of modifying the performance shaping factors and dependencies among tasks are provided

Risk-Driven Design Processes: Balancing Efficiency with Resilience in Product Design

Current design methods and approaches focus on increasing the efficiency of the product design system by, for example, eliminating waste and focusing on value creation. However, continuing failures in the development of complex, large scale products and systems point towards weaknesses in the existing approaches. We argue that product development organizations are hindered by the many uncertainties that are inherent in the process. Common management heuristics ignore uncertainty and thus overly simplify the decision making process. Creating transparency regarding uncertainties and the associated risks (i.e. effect of uncertainties on design objectives) is not seen as an explicit priority. Consequently organizations are unable to balance risk and return in their development choices. Product development processes do not emphasize reduction of risks, particularly those risks that are apparent early in the process. In addition, the resilience of the PD system, i.e. its ability to deliver on-target results under uncertainty, is not deliberately designed to match the level of residual uncertainty. This chapter introduces the notion of Risk-Driven Design and its four principles of 1. Creating transparency regarding design risks; 2. Risk-driven decision making; 3. Minimizing uncertainty; and 4. Creating resilience.Massachusetts Institute of Technology. Lean Advancement InitiativeCenter for Clean Water and Clean Energy at MIT and KFUP

NASA's Understanding of Risk in Apollo and Shuttle

Mathematical risk analysis was used in Apollo, but it gave unacceptably pessimistic resultsand was discontinued. Shuttle was designed without using risk analysis, under the assumptionthat good engineering would make it very safe. This approach led to an unnecessarily riskydesign, which directly led to the Shuttle tragedies. Although the Challenger disaster wasdirectly due to a mistaken launch decision, it might have been avoided by a safer design. Theultimate cause of the Shuttle tragedies was the Apollo era decision to abandon risk analysis

Building fragility curves of sliding failure of concrete gravity dams integrating natural and epistemic uncertainties

[EN] The proposed procedure combines the concepts of the Electrical Power Research Institute (EPRI) guidelines to develop fragility curves for the nuclear industry with existing reliability techniques for computing fragility curves in the context of concrete dams engineering. The procedure has been applied to a dam to illustrate how it can be used in a real case in such a manner that fragility curves are obtained integrating natural and epistemic uncertainties without losing track of their separate contribution to risk results. (C) 2016 Elsevier Ltd. All rights reserved.This paper was published with the support of the research project "INICIA" (Methodology for Assessing Investments on Water Cycle Infrastructures informed on Risk and Energy Efficiency Indicators, BIA2013-48157-C2-1-R, 2014-2016), co-funded by the Spanish Ministry of Economy and Competitiveness "Ministerio de Economia y Competitividad" (Programa Estatal de Investigacion, Desarrollo e Innovation Orientada a los Retos de la Sociedad) and the European Regional Development Fund (ERDF).Morales Torres, A.; Escuder Bueno, I.; Altarejos García, L.; Serrano Lombillo, AJ. (2016). Building fragility curves of sliding failure of concrete gravity dams integrating natural and epistemic uncertainties. Engineering Structures. 125:227-235. https://doi.org/10.1016/j.engstruct.2016.07.006S22723512

Nuclear terrorism and virtual risk: Implications for prediction and the utility of models

Assessing the risk of nuclear terrorism is a challenging task due to the diversity of actors involved, variety of pathways to success, range of defensive measures employed, and the lack of detailed historical record upon which to base a nalysis. Numerical models developed to date vary wildly in both approach and ultimate assessment: estimates of the likelihood a nuclear terrorist attack differ by up to nine orders of magnitude. This paper critiques existing efforts from the standpoint of probability theory, and proposes an alternative perspective on the utility of risk assessment in this area. Nuclear terrorism is argued to be a ‘virtual risk’ for which it is not possible to meaningfully ascribe a quantitative measure, making numerical estimates of the likelihood of nuclear terrorism misleading. Instead, we argue that focus should be placed on utilising models to identify areas of disagreement as targets for further research, with greater emphasis on understanding terrorist decision-making and adaption in response to nuclear security measures

How can health care organisations make and justify decisions about risk reduction? Lessons from a cross-industry review and a health care stakeholder consensus development process

Interventions to reduce risk often have an associated cost. In UK industries decisions about risk reduction are made and justified within a shared regulatory framework that requires that risk be reduced as low as reasonably practicable. In health care no such regulatory framework exists, and the practice of making decisions about risk reduction is varied and lacks transparency. Can health care organisations learn from relevant industry experiences about making and justifying risk reduction decisions? This paper presents lessons from a qualitative study undertaken with 21 participants from five industries about how such decisions are made and justified in UK industry. Recommendations were developed based on a consensus development exercise undertaken with 20 health care stakeholders. The paper argues that there is a need in health care to develop a regulatory framework and an agreed process for managing explicitly the trade-off between risk reduction and cost. The framework should include guidance about a health care specific notion of acceptable levels of risk, guidance about standardised risk reduction interventions, it should include regulatory incentives for health care organisations to reduce risk, and it should encourage the adoption of an approach for documenting explicitly an organisation’s risk position

The quantification of low-probability–high-consequences events: part I. A generic multi-risk approach

ISSN:0921-030XISSN:1573-084