Ingrid Bouwer Utne

A method for risk modeling of interdependencies in critical infrastructures

Failures in critical infrastructures may be hazardous to population, economy, and national security. There can be strong interdependencies between various infrastructures, but these interdependencies are seldom accounted for in current risk and vulnerability analyses. To reduce probability and mitigate consequences of infrastructure failures, these interdependencies have to be assessed. The objective of this paper is to present a method for assessing interdependencies of critical infrastructures, as part of a cross-sector risk and vulnerability analysis. The method is based on a relatively simple approach applicable for practitioners, but may be extended for more detailed analyses by specialists. Examples from a case study with the Emergency Preparedness Group of the city of Oslo, Norway, are included.

Risk analysis of critical infrastructures emphasizing electricity supply and interdependencies

Failures in critical infrastructures can cause major damage to society. Wide-area interruptions (blackouts) in the electricity supply system have severe impacts on societal critical functions and other critical infrastructures, but there is no agreed-upon framework on how to analyze and predict the reliability of electricity supply. Thus, there is a need for an approach to cross-sector risk analyses, which facilitates risk analysis of outages in the electricity supply system and enables investigation of cascading failures and consequences in other infrastructures. This paper presents such an approach, which includes contingency analysis (power flow) and reliability analysis of power systems, as well as use of a cascade diagram for investigating interdependencies. A case study was carried out together with the Emergency Preparedness Group in the city of Oslo, Norway and the network company Hafslund Nett. The case study results highlight the need for cross-sector analyses by showing that the total estimated societal costs are substantially higher when cascading effects and consequences to other infrastructures are taken into account compared to only considering the costs of electricity interruptions as seen by the network company. The approach is a promising starting point for cross-sector risk analysis of electricity supply interruptions and consequences for dependent infrastructures.

Risk of collision between service vessels and offshore wind turbines

Offshore wind farms are growing in size and are situated farther and farther away from shore. The demand for service visits to transfer personnel and equipment to the wind turbines is increasing, and safe operation of the vessels is essential. Currently, collisions between service vessels and offshore wind turbines are paid little attention to in the offshore wind energy industry. This paper proposes a risk assessment framework for such collisions and investigates the magnitude of the collision risk and important risk-influencing factors. The paper concludes that collisions between turbines and service vessels even at low speed may cause structural damage to the turbines. There is a need for improved consideration of this kind of collision risk when designing offshore wind turbines and wind farms.

Maintenance strategies for deep‐sea offshore wind turbines

Purpose – The objective of this paper is to outline a framework that guides the development of sound maintenance strategies and policies for deep‐sea offshore wind turbines.Design/methodology/approach – An important challenge with offshore wind energy production is to reduce the high operation and maintenance costs. To decrease complexity, and structure the maintenance strategy developing process, systems engineering principles are used.Findings – The framework facilitates integration of fragmented but valuable information from different disciplines in the development of sound maintenance strategies. In addition, the framework may be used to identify knowledge gaps, and areas for further research.Research limitations/implications – The paper refers to research on deep‐sea offshore wind turbines, which is in its infancy, with a limited amount of data yet available for verification and validation. Deep‐sea offshore installations are not commercialized, and few pilot installations have been installed.Origina...

Use of dynamic Bayesian networks for life extension assessment of ageing systems

Extending the operating lifetime of ageing technical systems is of great interest for industrial applications. Life extension requires identifying and selecting decision alternatives which allow for a safe and economic operation of the system beyond its design lifetime. This article proposes a dynamic Bayesian network for assessing the life extension of ageing repairable systems. The main objective of the model is to provide decision support based on the system performance during a finite time horizon, which is defined by the life extension period. The model has three main applications: (i) assessing and selecting optimal decision alternatives for the life extension at present time, based on historical data; (ii) identifying and minimizing the factors that have a negative impact on the system performance; and (iii) reassessing and optimizing the decision alternatives during operation throughout the life extension period, based on updating the model with new operational data gathered. A case study illustrates the application of the model for life extension of a real firewater pump system in an oil and gas facility. The case study analyzes three decision alternatives, where preventive maintenance and functional test policies are optimized, and the uncertainty involved in each alternative is computed.

Integrating RAMS engineering and management with the safety life cycle of IEC 61508

This article outlines a new approach to reliability, availability, maintainability, and safety (RAMS) engineering and management. The new approach covers all phases of the new product development process and is aimed at producers of complex products like safety instrumented systems (SIS). The article discusses main RAMS requirements to a SIS and presents these requirements in a holistic perspective. The approach is based on a new life cycle model for product development and integrates this model into the safety life cycle of IEC 61508. A high integrity pressure protection system (HIPPS) for an offshore oil and gas application is used to illustrate the approach.

Common patterns in aggregated accident analysis charts from human fatigue-related groundings and collisions at sea

Research has shown that there are potentially disastrous outcomes of human fatigue at sea. The conditions in which the seafarers have to operate are becoming more and more demanding. The study in this article attempts to aggregate accident charts derived from in-depth studies of human fatigue-related accidents to determine common patterns of interlinked fatigue factors. The accidents are analyzed by means of the Cognitive Reliability and Error Analysis Method (CREAM), which in the article has been modified for maritime accidents. The main fatigue factors identified are ‘shift work’, ‘irregular working hours’, ‘inadequate task allocation’, and ‘excessive demands’. The study reveals several differences between ship collision and grounding accidents and their corresponding fatigue factors. Human fatigue-related collision accidents are characterized by wrong/badly timed decisions, misconceptions, and poor communication between the vessels. Right before the collision the crew is often panicking and mistakes are easily made. In human fatigue-related groundings, the conditions are often monotonous and the navigating officer has either overlooked the upcoming seabed or simply fallen asleep. Safety climate issues are also identified as important contributors to human fatigue.

Routing and Scheduling of Maintenance Fleet for Offshore Wind Farms

Reducing the operation and maintenance (O&M) cost is a necessity in current offshore wind farms so that the produced power can achieve a competitive price in the market. An offshore wind farm normally comprises a large number of turbines which demand frequent maintenance visits. In addition to making maintenance plans that avoid downtime and production losses, it is important to utilize the expensive resources, such as service vessels, in an efficient way. This article introduces the routing and scheduling problem of a maintenance fleet for offshore wind farms (RSPMFOWF), which is to determine the optimal assignments of turbines and routes to the vessels in terms of cost. Simultaneously considering the characteristics and limitations in this problem, we present the mathematical formulations for the RSPMFOWF. A computational case study is also carried out. The results provide both the optimized cost and detailed arrangements, which can be directly used in maintenance planning.

Exposed Aquaculture in Norway

Farming of Atlantic salmon in exposed areas poses unique challenges to operations, structures and equipment due to severe and irregular wind, wave and current conditions, and sheer remoteness. Many of the operational challenges seen at present sheltered sites are likely to be amplified when moving production to more exposed locations. There is, however, a strong Norwegian industrial interest in utilizing such areas. A new research center, the Exposed Aquaculture Operations center has been initialized to develop competence and technology to address the challenges. Six core research areas are identified that will be crucial to address the challenges with exposed farming, with a focus on the industrial status in Norway. Four areas target technological innovations that will enable safe and reliable exposed aquaculture operations: 1) Autonomous systems and technologies for remote operations, 2) Monitoring and operational decision support, 3) Structures for exposed locations and 4) Vessel design for exposed operations. Two areas represent core requirements for sustainable production: 5) Safety and risk management and 6) Fish behavior and welfare. This paper describes the research needs and the research strategy planned for the Exposed Aquaculture Operations center.

A systems approach to risk analysis of maritime operations

Technological innovations and new areas of application introduce new challenges related to safety and control of risk in the maritime industry. Dynamically positioned systems are increasingly used, contributing to a higher level of autonomy and complexity aboard maritime vessels. Currently, risk assessment and verification of dynamically positioned systems are focused on technical reliability, and the main effort is centered on design and demonstration of redundancy in order to protect against component failures. In this article, we argue that factors, such as software-requirement errors, human errors, including unsafe or too late decision-making, and inadequate coordination between decision makers, also should be considered in the risk assessments. Hence, we investigate the feasibility of using a systems approach to analyzing risk in dynamically positioned systems and present an adapted version of the system-theoretic process analysis. A case study where the system-theoretic process analysis is applied to a dynamically positioned system is conducted to assess whether this method significantly expands the current view on safety of dynamically positioned systems. The results indicate that the reliability-centered approaches, such as the failure mode and effect analysis, sea trials, and hardware-in-the-loop testing, are insufficient and that their view on safety is too narrow. This article shows that safety constraints can be violated in a number of manners other than component failures for dynamically positioned systems, and hence, system-theoretic process analysis complements the currently applied methods.