Assumed risk losses from

Accident scenarios that assume no loss of hydrogen due to buoyancy-driven convection can considerably overestimate the risk incurred in hydrogen escapes. In reality, hydrogen s very low density prevents this accident scenario from occurring. 

Figure 18-5 Top Events. The top tiers of the MORT chart indicate that the losses resulting from the accident being investigated result from oversights and omissions or assumed risks or both.

The oversights and omissions and assumed (accepted) risks tier of the tree is relatively academic and generally adds to the analysis. A formal accident investigation is unlikely to be performed on losses that result from assumed risks only. Losses from assumed risks are normally those from earthquakes, tornados, hurricanes, and other acts of nature. (Of course, exceptions exist, as do situations in which certain losses due to even remote acts of nature are not acceptable.)... 

Risk sensitivity results are also very useful in identifying key elements in your existing loss prevention program. For example, suppose your fire protection system was assumed to have a very low probability of failure because you test it weekly. Fire protection failures may not show up as an important contributor to your total risk (because failure is so unlikely), but your total risk estimate may be extremely sensitive to any change in the probability of fire protection failures. Flence you should not divert resources away from testing the fire protection system unless the alternate use of funds will decrease risk more than the reduced testing will increase risk. 

Finally, one of the most difficult types of crises to address is the death of a client. People with drug problems often lead very risky lives, and the threat of death may be ever present with such clients. People who use drugs are at risk from infectious diseases such as hepatitis and AIDS, from suicide and homicide, and from accidents. The saddest events in my professional career have been associated with losing a client. Such losses burden professionals, who may assume some level of responsibility for the death or may feel a sense of loss in not being able to meet with the client any more. Be aware that caregivers sometimes need care themselves, and this is one particular situation in which that may be true. Do not be shy about seeking help if you feel that the death of a client has adversely affected your professional or personal life. 

Disclaimer The recommendations, advise, descriptions, and the methods in this book are presented solely for educational puiposes. The author and publisher assume no liability whatsoever for any loss or damage that results from the use of any of the material in this book. Use of the material in this book is solely at the risk of the user. 

The scope of the analysis aims to identify the process under consideration, in which plant it will take place, and with which chemicals it will be performed. The chemical reactions and unit operations must be clearly characterized. In this step, it is also important to check for interface problems with other plant units. As an example, when considering raw material delivery, it can be assumed that the correct raw material of the intended quantity and quality is delivered from a tank farm. Thus, it can be referred to the tank farm risk analysis, or the tank farm is to be included in the scope of the analysis. Similar considerations can be made for energy supply, to ensure that the appropriate energy is delivered. Nevertheless, loss of energy must be considered in the analysis, but it will be assumed that... 

As an alternative to the assumption of a one-time exposure for 1,000 h at the time of facility closure, permanent occupancy of a disposal site following loss of institutional control could be assumed (see Section 7.1.3.4). The assumption of chronic lifetime exposure would affect the analysis for hazardous chemicals that induce deterministic effects only if estimated intakes due to additional pathways, such as consumption of contaminated vegetables or other foodstuffs produced on the site, were significant. Based on the results for lead in Table 7.8, an intake rate from additional pathways of about 50 percent of the assumed intake rate by soil ingestion, inhalation, and dermal absorption would be sufficient to increase the deterministic risk index above unity. The importance of additional pathways was not investigated in this analysis, but they clearly would warrant consideration. The increase in exposure time during permanent occupancy does not otherwise affect the analysis for chemicals that induce deterministic effects, provided RfDs are appropriate for chronic exposure, because chronic RfDs incorporate an assumption that the levels of contaminants in body organs relative to the intake rate (dose) are at steady state. 

Okrent and Xing (1993) estimated the lifetime cancer risk to a future resident at a hazardous waste disposal site after loss of institutional control. The assumed exposure pathways involve consumption of contaminated fruits and vegetables, ingestion of contaminated soil, and dermal absorption. The slope factors for each chemical that induces stochastic effects were obtained from the IRIS (1988) database and, thus, represent upper bounds (UCLs). The exposure duration was assumed to be 70 y. Based on these assumptions, the estimated lifetime cancer risk was 0.3, due almost entirely to arsenic. If the risk were reduced by a factor of 10, based on the assumption that UCLs of slope factors for chemicals that induce stochastic effects should be reduced by this amount in evaluating waste for classification as low-hazard (see Section 7.1.7.1), the estimated risk would be reduced to 0.03. Either of these results is greater than the assumed limit on acceptable risk of 10 3 (see Table 7.1). Thus, based on this analysis, the waste would be classified as high-hazard in the absence of perpetual institutional control to preclude permanent occupancy of a disposal site. 

The concept of a hypothetical inadvertent intruder at a nearsurface waste disposal site, including permanent occupants of a site after an assumed loss of institutional control, provides a suitable basis for defining exposure scenarios that would be used to calculate risks that arise from waste disposal and the boundaries between waste classes. For other dispositions of waste, alternative scenarios would need to be developed and evaluated. 

A second method may be used in which the company assumes all the risk and no payments are made into a reserve fund. This method is designated as self-assumption of risk. Partial self-insurance may be obtained through the purchase of deductible insurance from regular agencies. The purchaser assumes the risk up to a certain amount and the insurance company agrees to pay for any additional losses. 

The desire to predict the future often leads to collecting a large amount of information based on the hope that something useful will be obtained and noticed. The NASA Space Shuttle program was collecting six hundred metrics a month before the loss of Columbia. Companies often collect data on occupational safety, such as days without a lost time accident, and they assume that these data reflect on system safety [17], which of course it does not. Not only is this misuse of data potentially misleading, but collecting information that may not be indicative of real risk diverts limited resources and attention from more effective risk-reduction efforts. 

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