Risk assessment plant

Sundararajan, C. 1992. Structural Engineering Aspects of Plant Risk Assessment. 

Kido, C. A Bibliography of Data Bases for Nuclear Power Plant Risk Assessment. EGG-EA-6100, November 1982. 

Chemical plants—Risk assessment 4. Risk management. 

Nuclear power plants — Risk assessment. 2. Nuclear power plants — Safety measures. I. International Atomic Energy Agency. II. Series. 

In a nuclear facility, as in any industrial plant, risk assessment distinguishes between the potential hazards that might be encountered in the absence of any protective measures, and the residual risks that will still remain despite the measures taken. The problem lies in assessing the latter, since there is no way of ensuring that they have been completely eliminated. The concept of event probability and its associated consequences was rapidly incorporated into safety analysis procedures, by taking account of the fact that the probability of an accident must be inversely proportional to the severity of the potential consequences for the public and the environment. 

This section describes the potential causes of common mode failure (CMF), how we can design l C systems to prevent CMF, and how we can take possible CMF into account when doing plant risk assessments. It addresses both software and hardware systems and components. Common mode failure can also be referred to as common-cause failure or dependent failure. Some people may say that there are subtle differences between these terms, but let us keep it simple. 

PROGRAMMABLE CONTROLLER FAULT TREE MODELS FOR USE IN NUCLEAR POWER PLANT RISK ASSESSMENTS... 

Bendixen L.M., O Neil J.K. and Little A.D., (1984) Chemical Plant Risk Assessment Using HAZOP and Fault Tree Methods , Plant/Operations Progress, Vol. 3, No. 3, pp. 179-184. 

The purpose of hazard analysis and risk assessment ia the chemical process industry is to (/) characterize the hazards associated with a chemical facihty (2) determine how these hazards can result in an accident, and (J) determine the risk, ie, the probabiUty and the consequence of these hazards. The complete procedure is shown in Figure 1 (see also Industrial hygiene Plant safety). 

Many companies use worker—management teams, suggestion boxes, consultant surveys, suppHer training sessions, and other methods to reduce risk of injuries (see Hazard analysis and risk assessment). The principal regulatory burden falls on wastes and discharges which leave the plant (3,53,54). 

Risk-Based Inspection. Inspection programs developed using risk analysis methods are becoming increasingly popular (15,16) (see Hazard ANALYSIS AND RISK ASSESSMENT). In this approach, the frequency and type of in-service inspection (IS I) is determined by the probabiUstic risk assessment (PRA) of the inspection results. Here, the results might be a false acceptance of a part that will fail as well as the false rejection of a part that will not fail. Whether a plant or a consumer product, false acceptance of a defective part could lead to catastrophic failure and considerable cost. Also, the false rejection of parts may lead to unjustified, and sometimes exorbitant, costs of operation (2). Risk is defined as follows ... 

Hazard and Risk Assessment Tools The hazard and risk assessment tools used vary with the stage of the project from the early design stage to plant operations. Many techniques are available, both quahtative and quantitative, some of which are hsted in the following section. Reviews done early in projects often result in easier, more effective changes. 

Nuclear Regulatory Commission, PRA Procedures Guide—A Guide to the Performance of Probabilistic Risk Assessments for Nuclear Power Plants, NUREG/CR-2300, Jantiaiy 1983. 

Hazard analysis (HAZAN) is a quantitative way of assessing the likelihood of failure. Other names associated with this technique are risk analysis, quantitative risk assessment (QRA), and probability risk assessment (PRA). Keltz [44] expressed the view that HAZAN is a selective technique while HAZOP can be readily applied to new design and major modification. Some limitations of HAZOP are its inability to detect every weakness in design such as in plant layout, or miss hazards due to leaks on lines that pass through or close to a unit but cany material that is not used on that unit. In any case, hazards should... 

Transportation should be considered when assessing risks associated with planned or existing plants. The design of new chemical processing units should include at the earliest opportunity a qualitative or quantitative risk assessment of the whole system including production, use, and transportation in order to minimize overall risk. A brief discussion of the inherent safety aspects of transportation is included in Chapter 5. 

Plant designs should be based on a risk assessment that considers the process and the site in detail as well as all of the principles of inherently safer operation. Earlier decisions may limit the options in... 

Fleming, K. N. et al., 1979, A Methodology for Risk Assessment of Major Fires and Its Application to an HTGR Plant, General Atomic GA-A15401. 

GAO, 1985, Probabilistic Risk Assessment An Emerging Aid to Nuclear Power Plant Safety Regulation, GAO/RCED-85-11, June,... 

Potash, L. M. et al., Experience in Integrating the Operator Contributions of the PRA of Actual Operating Plants, Proceeding of the ANS/ENS September 1981 Topical Meeting on Prbabilisitic Risk Assessment, Port Chester, NY pp 1054-1063, ANS. 

Roger, C., J. L. Boccio, and M. A. Azarm, 1985, Evaluation of Current Methodology Employed in Probabilistic Risk Assessment of Fire Events at Nuclear Power Plants, BNL report A-3710, February. 

The last three decades have seen the development of a new science to help us better understand the risk of events about which there is often very little information. The reason there is interest in such a science is that there are a great many societal benefits from activities that involve risk risk that if properly managed through better understanding can greatly benefit the quality of all life on the planet earth, both plant and animal. That science is quantitative risk assessment, also known by such names as probabilistic risk assessment and probabilistic salety assessment, the latter being the preferred name for this text. Probabilistic safety assessment divides the risk question into three questions "What can go wrong " "How likely is it " and "What are the consequences "... 

Figure 1 shows part of a solvent phase polypropylene plant. The plant consists of three process lines, denoted A, B, and C. During a risk assessment review, a scenario was identified that involved a release of reactor contents from a location near the west end of the A line. Estimates are needed of the blast overpressures that would occur if the resulting cloud of vapor, mist, and power ignites. 

Capital Project Review and Design Procedures (for new or existing plants, expansions, and acquisitions) Appropriation request procedures Risk assessment for investment purposes Hazards review (including worst credible cases)... 

A program of research has been supported for several years by the United Kingdom Health Safety Executive (HSE) to address the effects of sociotechnical factors on risk in the CPI. The initial emphasis of this work was to develop a methodology so that chemical process quantitative risk analysis (CPQRA) would take into accotmt the effects of the quality of the management factors of plant being assessed. This work has been described in a series of publications (e.g., Bellamy et al., 1990 Hurst et al., 1991 Geyer et al., 1990 and Hurst et al., 1992). 

Performance-influencing factors analysis is an important part of the human reliability aspects of risk assessment. It can be applied in two areas. The first of these is the qualitative prediction of possible errors that could have a major impact on plant or personnel safety. The second is the evaluation of the operational conditions under which tasks are performed. These conditions will have a major impact in determining the probability that a particular error will be committed, and hence need to be systematically assessed as part of the quantification process. This application of PIFs will be described in Chapters 4 and 5. 

Generally, risk assessment has focused on the first type of error, since the main interest in human reliability was in the context of human actions that were required as part of an emergency response. However, a comprehensive Consequence Analysis has to also consider other types, since both of these outcomes could constitute sources of risk to the individual or the plant. 

There is considerable interest in developing a database on human error probabilities for use in chemical process quantitative risk assessment (CPQRA). Nevertheless, there have been very few attempts to develop such a database for the CPI compared, for example, with the nuclear industry. Some of the reasons for this are obvious. The nuclear industry is much more highly integrated than the CPI, with a much greater similarity of plant equipment... 

U.S. Nuclear Power Plants. Big Rock Point Probabilistic Risk Assessment. 4.8-1... 

A risk estimate indicates Uie likelihood of occurrence of the different types of health or enviroinnental effects in exposed populations. Risk assessment should include both liuimn health and environmental evaluations (i.c., impacts on ecosystems). Ecological impacts include actual or potential effects on plants and animals (other than domesticated species). The number produced from the risk characleriznlion, representing the probability of adi crse... 

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