A RISK BASED APPROACH TO HUMAN VULNERABILITY MODELLING AND OCCUPIED BUILDING ANALYSIS

摘要

Recent accidents like Buncefield and Texas City have put risk to people from explosion high on the agenda, particularly with respect to risks to those in buildings. Regulatory regimes for land use planning and occupied buildings are becoming more demanding and the need for accuracy and transparency has increased. For example, regulatory guidelines like API RP752 and RP753 provide guidance on the design and location of permanent and portable buildings to minimise risks to occupants. This paper focuses on advances in software models for assessing risks to people in buildings from releases of hazardous materials, particularly those which are flammable and may result in VCE's creating large overpressures.When deciding on the location and construction of occupied buildings in the vicinity of hazardous installations, a number of factors must be considered during the design and operational phases. Key to the process of deciding where to locate buildings and what level of protection they should offer their occupants are the level of risk to which it is acceptable to expose those occupants. Traditional QRA tends to use "generic" vulnerability for people indoors where their probability of death when particular levels of different types of hazardous effects are exceeded, such as explosion overpressure, radiation from fires, flame impingement or toxicity, is treated as being independent of the type of building within which they reside. This is obviously a significant limitation to using the results of traditional QRA in selecting appropriate building types in different situations or to locate buildings in the safest place from the standpoint of risk to occupants. Risk to individuals within buildings is a function of both building location and construction. In order to minimise risk to personnel in the most cost effective way, plant designers and safety managers need to be able to compare and assess different options with ease.This paper describes recent advances to the vulnerability modelling capabilities of the Phast Risk QRA tool. These new features enable individual definition of building types and associated occupant vulnerability. In addition, GIS facilities allowing analysts to locate buildings of a particular type in various locations help ensure overall risks can be minimised, or location specific risks for particular buildings can be assessed. A case study and some hypothetical explosion risk scenarios using the Multi Energy explosion model (Cavanagh et al., 2009; Cavanagh, 2010) illustrate the application of the new vulnerability modelling to selecting suitable building types, and locating them in the most appropriate position to minimise the fatality risks to occupants. In addition, techniques are described for using these tools and methods to help locate and design buildings to withstand the possible explosion and radiation loads they may be subjected to.