Glossary
Accident An unexpected and undesirable event, especially one resulting in damage or harm.
Acetaldehyde An organic chemical compound.
Anomalies Deviation or departure from the normal or common order, form, or rule.
Basic event A fault or failure in an accident sequence that can occur, which has an impact on the overall outcome or the top event of a probabilistic risk assessment or fault tree analysis.
Bioconcentration Uptake and accumulation of a substance from water alone.
Biomagnification The increase in concentration of a substance such as the pesticide, DDT.
Boundary conditions The values or conditions that constrain a system.
Chloracne An acnelike eruption of blackheads, cysts, and pustules.
Closed loop Materials do not enter or leave a system.
Component System, job/person, part, tool, or other thing that performs the activities that make up the critical function.
Component failure An electronic or mechanical part of a system that ceases to work. In risk assessment terms, this unit has an impact on the success or failure of a system.
Component fault An electronic or mechanical part of a system that ceases to work or ceases to work correctly. In risk assessment terms, this unit has an impact on the success or failure of a system.
Conditional probability A probability whose sample space has been limited to only those outcomes that fulfill a certain condition.
Consequences The positive or negative outcomes of decisions, events, or processes.
Critical function What has to be in place to achieve or maintain the mission.
Cut set A set of basic events that lead to the top event in a probabilistic risk assessment or fault tree.
Delphi process A structured communication technique, originally developed as a systematic, interactive forecasting method, which relies on a panel of experts.
Discrete distribution A statistical distribution that has specific values.
Event tree A graphical representation of the possible sequence of events that might occur following an event that initiates an accident.
Failure mode and effects analysis (FMEA) A detailed document that identifies the ways in which a process or product can fail to meet critical requirements. It is a living document that lists all the possible causes of failure from which a list of items can be generated to determine types of controls or where changes in the procedures should be made to reduce or mitigate risk.
Failure mode, effects, and criticality analysis (FMECA) The additional dimension of probability and criticality added to FMEA(s) by the prioritization of steps/sections of procedures that need to be changed or the process changed to reduce risk; pointing out where warnings, cautions, or notes need to be added in procedures; and pointing out where special precautions need to be taken or specialized teams/individuals need to perform tasks. The criticality is mainly a qualitative measure of how critical the failure to the process really is based on subject matter experts' opinion and based on probability of occurrence and/or on the consequence or effect.
Fault tree analysis A form of safety analysis that assesses hardware safety to provide failure statistics and sensitivity analyses that indicate the possible effect of critical failures.
Gates Logic structures in a fault tree that connect basic events.
Hazard Any risk to which a worker is subject to as a direct result (in whole or in part) of his being employed.
Hazmat Hazardous materials.
Human reliability analysis (HRA) Used to analyze the human response to an equipment failure and any process or activity that involves humans is susceptible to human error. HRAs are used to quantify the probability of human errors and can be used to identify steps or activities in the process that can be targeted for changes that could reduce the probability of human error.
Hydrazine A colorless, fuming, corrosive hygroscopic liquid, H2NNH2, used in jet and rocket fuels.
Involuntary risks Those associated with activities that happen to us without our prior consent or knowledge. Acts of nature such as being struck by lightning, fires, floods, tornados, and so on and exposure to environmental contaminants are examples of involuntary risks.
Methylmercury A bioaccumulative environmental toxicant.
Minamata disease A neurological syndrome caused by severe mercury poisoning.
Mission Goal of process, organization, or task.
Nanoparticles A small object that behaves as a whole unit in terms of its transport and properties.
Nomenclature The terminology used in a particular science, art, activity, and so on.
Nominal value The value of a security that is set by the company issuing it, unrelated to market value.
Perception The process of interpreting sensory stimuli by filtering it through one's experiences and knowledge base.
Preliminary hazard analysis A hazard analysis performed at the very beginning of a product or facility life cycle to determine the hazards.
Preliminary hazards list Hazards initially determined from an analysis.
Probabilistic risk assessment (PRA) Focuses on equipment failures and may included a section that discusses the probability of human failure being the initiating event.
Probability The likelihood that the event will occur.
Qualitative analysis Nonquantitative analysis. An analysis that is descriptive in nature.
Quantitative analysis An analysis that seeks to determine the numerical value of something.
Reverse engineer The process of discovering the technological principles of a man-made device, object, or system through analysis of its structure, function, and operation. It often involves taking something (e.g., a mechanical device, electronic component, or software program) apart and analyzing its workings in detail to be used in maintenance or to try to make a new device or program that does the same thing without using or simply duplicating (without understanding) any part of the original.
Risk The potential for realization of unwanted, adverse consequences to human life, health, property, or the environment; estimation of risk is usually based on the expected value of the conditional probability of the event occurring times the consequence of the event given that it has occurred.
Risk analysis A detailed examination, including risk assessment, risk evaluation, and risk management alternatives, performed to understand the nature of unwanted, negative consequences to human life, health, property, or the environment; an analytical process to provide information regarding undesirable events; the process of quantification of the probabilities and expected consequences for identified risks.
Risk assessment The process of establishing information regarding acceptable levels of a risk and/or levels of risk for an individual, group, society, or the environment.
Risk estimation The scientific determination of the characteristics of risks, usually in as quantitative a way as possible. These include the magnitude, spatial scale, duration, and intensity of adverse consequences and their associated probabilities as well as a description of the cause and effect links.
Risk evaluation A component of risk assessment in which judgments are made about the significance and acceptability of risk.
Risk homeostasis theory In any activity, people accept a certain level of subjectively estimated risk to their health, safety, and other things they value, in exchange for the benefits they hope to receive from that activity (transportation, work, eating, drinking, drug use, recreation, romance, sports, or whatever).
Risk identification Recognizing that a hazard exists and trying to define its characteristics. Often risks exist and are even measured for some time before their adverse consequences are recognized. In other cases, risk identification is a deliberate procedure to review and, it is hoped, anticipate possible hazards.
Risk perception An individual or group assessment of the potential for negative consequence.
Statistically nonverifiable Risks from involuntary activities that are based on limited data sets and mathematical equations.
Statistically verifiable Risks for voluntary or involuntary activities that have been determined from direct observation.
Support Utilities, materials, activities, or other items that support the components.
Target risk A specific level of risk an organization feels comfortable with and aims to achieve.
Task analysis Task analysis is any processes of assessing what a user does and why, step by step, and using this information to design a new system or analyze an existing system.
TOP events The event of interest in a probabilistic risk assessment or fault tree analysis to which all other basic events feed.
Undeveloped event Events with little information or no information or those that do not need to be developed because they concern things such as weather or other natural events.
Voluntary risks Those associated with activities that we decide to undertake (e.g., driving a car, riding a motorcycle, drinking, and driving).