Acceptable Risk Process

The Acceptable Risk Process was the basis for all technical decision making at NASA, from daily decision making to the formalized, final decision process immediately prior to a launch known as the FRR. The Acceptable Risk Process was first set forth in the Space Shuttle Safety Assessment Report, issued prior to the first shuttle launch in 1981. Similar to the hazard analysis and tracking process introduced in Chapter 3, a hazard was classified by NASA as an acceptable risk only after... 

The basic tenets of the proposed policy is to encourage the manufacturer to reduce or eliminate the N-nitroso contaminant level in his product, or failing this to establish that the level does not exceed an "acceptable risk to the user of the pesticide or the general public. This latter process of evaluation also requires that the Agency consider the benefits of this pesticide together with the risk in order to reach a final decision. Since there might be hundreds of products falling under this policy, the... 

Risk is the product of the probability of a release, thepjpbability of exposure, and the consequences of the exposure. Risk is usually described graphically, as shown in Figure 11-15. All companies decide their levels of acceptable risk and unacceptable risk. The actual risk of a process or plant is usually determined using quantitative risk analysis (QRA) or a layer of protection analysis (LOPA). Other methods are sometimes used however, ORA and LOPA are the methods that are most commonly used. In both methods the frequency of the release is determined using a combination of event trees, fault trees, or an appropriate adaptation. 

Managing Risk and Reliability of Process Plants, Gulf Professional, Houston, Tex, 2003, p. 70) suggests that accepted risk is a better term because it makes it clear that the risk has been accepted by those responsible for the decisions on how to build, operate, and regulate the facility. 

Benefits are often more important than risks to consumers. Consumers become willing to accept products processed with specific technologies when they become convinced that these products offer significant benefits over other products. These benefits can include decreases in price as well as increases in product quality, such as taste and naturalness purity, such as reduced use of chemicals and wholesomeness, such as better nutrition (Kuznesof and Ritson, 1996). Hamstra (1995) reported that perceived benefits of biotechnology products had greater statistical influences on Dutch consumer attitudes and acceptance than perceived risks. 

The liquid and solid effluents are well characterized. As the ACW I Committee noted in its original and supplemental reports, the gaseous process emissions will have to be characterized for health risk assessments and environmental risk assessments required by EPA guidelines (NRC, 1999, 2000a). These results, along with the results of analyses of metals emissions (including chromium VI), can be used to assess the environmental impact of a facility through accepted risk-assessment methods (EPA, 1998). 

Risk assessment is the conventional tool for decision making on the acceptability of chemical use. It is based on predicted exposure levels, predicted no-effect levels of individual chemicals and politically defined degrees of acceptable risk. Each of these processes involves a series of value judgements and estimations. Risk assessment is therefore highly subjective. 

Reduction of Inventories Advancements in process control and changing acceptable risk standards may have removed the initial justification for large inventories of hazardous raw materials or products. For example, tight quality control of on-time deliveries of hazardous raw materials may allow for a one or two day supply on hand versus a one- or two-week supply. 

HAZAN, on the other hand, is a process to assess the probability of occurrence of such accidents and to evaluate quantitatively the consequences of such happenings, together with value judgments, in order to decide the level of acceptable risk. HAZAN is also sometimes referred to as Probabilistic Risk Assessment (PRA) and its study uses the well-established techniques of Fault Tree Analysis and/or Event Tree Analysis ... 

The accepted risk is a risk inferior to a level defined in advance either by law, technical, economical, or ethical considerations. The risk analysis, as it will be described in the following sections, has essentially a technical orientation. The minimal requirement is that the process fulfils requirements by the local laws and that the risk analysis is carried out by an experienced team using recognized methods and risk-reducing measures that conform to the state of the art It is obvious that non-technical aspects may also be involved in the risk acceptation criteria. These aspects should also cover societal aspects, that is, a risk-benefit analysis should be performed... 

Establishing the boundaries in a risk-based waste classification system requires that one or more values of acceptable risk be specified. The values of acceptable risk are then used to establish the values of parameters that define the boundaries of the different waste classes. The process of establishing the value(s) of acceptable risk is part of risk management. Risk management is an essential aspect of establishing a waste classification system, but it has an important nontechnical component that reflects societal values. 

The waste classification system developed in this Report includes a general class of exempt waste. Waste in this class would contain sufficiently small amounts of hazardous substances that it could be managed in all respects as if it were nonhazardous (e.g., as household trash). NCRP intends that exempt materials could be used or disposed of in any manner allowed by laws and regulations addressing disposition of nonhazardous materials. However, exempt waste would not necessarily be exempt for purposes of beneficial use without further analysis of the risks associated with anticipated uses. Materials could be exempted for purposes of disposal or beneficial use based on similar considerations of acceptable risk. However, based on differences in exposure scenarios for the two dispositions, limits on the amounts of hazardous substances that could be present in exempt materials intended for beneficial use could be substantially lower than the limits for disposal as exempt waste. Thus, disposal may be the only allowable disposition for some exempt materials based on considerations of risk. In addition, some exempt materials may consist of trash, rubble, and residues from industrial processes that would have no beneficial uses and must be managed as waste. 

Jeff is a talented Staff Engineer employed by a major chemical plant in West Virginia he has a solid background in Loss Prevention. Jeff Josecks article was written to spark interest and discussion of process safety in safety meetings. It is also very skillfully worded to spark the readers into thinking about acceptable risks and minimal risks. 

If, on the other hand, one is interested in determining the minimum acceptable sample process capability index Cp required to have some stated confidence 100(1 — a)% that the true Cp is above some value (e.g., Cp = 1.0), one can use the following equation for a particular Cp, sample size n, and risk level a ... 

---