The selected accidents

Table 13 The selected accidents and their identical predecessors from FACTS.

This section summarizes the methods used to evaluate and quantify the consequences of operational accidents, natural phenomena events, and external events selected in Section 3.3.2.3.5, Accident Selection as DBAs. Consequences to the public and the environment stem from airborne releases of radioactive material since no liquid or solid radioactive material would be released in the selected accidents. The airborne pathway is of primary interest for releases from nonreactor nuclear facilities according to DOE-STD-1027-92 (DOE 1997). Exposure to direct or scattered radiation is a hazard only for workers due to the distance to the public. 

A pragmatic choice of design target which is often based on rather conservative analyses of the selected accidents is characteristic to the DBA concept. However, the choice is based on collected experience and expert judgement. 

Accidents are presented on the map with accident identifiers, each consisting of a symbol (yellow dot with red outline) and a letter representing the most severe accident that occurred on the location. For each location on the map, the user can access the data associated with it. A mouse click on each accident identifier on the map provides access to data on all accidents at a specific location which are in accordance with the selected criteria. Also available are data related to the road a specific accident occurred on and data on topographic entities at the loeation. The data is shown in an information cloud pop-up (Figure 19.11), which also includes a link to the participant data for the selected accident. A mouse click on the link opens a new window with relevant data on all accident participants (Figure 19.12). 

Automotive and architectural laminates of PVB develop maximum impact strength near 20°C, as shown in Figure 2. This balance is obtained by the plasticizer-to-resin ratio and the molecular weight of the resins. It has been adjusted to this optimum temperature based on environmental conditions and automobile population at various ambient temperatures. The frequency and severity of vehicle occupant injuries vs temperature ranges at the accident location have been studied (5), and the results confirm the selection of the maximum performance temperature and decreasing penetration resistance at temperature extremes. 

E)ocumentation of flash fires is scarce. In several accident descriptions of vapor cloud explosions, flash fires appear to have occurred as well, including those at Flixborough, Port Hudson, East St. Louis, and Ufa. The selection and descriptions of flash fires were based primarily on the availability of information. 

One of the most important elements of the PSM Rule is the process hazard analysis (PrHA). It requires the systematic identification of hazards and related accident scenarios. The PSM Rule allows the use of different analysis methods, but the selected method must be based on the process being analyzed. The PSM Rule specifies that PrHAs must be completed as soon as possible within a 5-year period. However, one-fourth of the PrHAs must have been completed by May 26, 1994, with an additional one-fourth completed each succeeding year. The highest risk processes were to be done first. A schedule for PrHAs must be established at the outset of a process safety management (PSM) program to give priority to the highest risk processes. PrHAs must be reviewed and updated at least every 5 years. 

Under the PSM Rule, the PrHA element requires the selection and application of appropriate hazard analysis methods to systematically identify hazards and potential accident scenarios associated with highly hazardous chemicals. The components of a PrHA are summarized and explained below. 

The selection process of retrieving these case histories from the 18,000 is based on the availability of rich accident data located within the chemical process industry. A detailed discussion of the selection process can be found in Chapters 3 and 6. 

In addition to these selection criteria, the limitations of the author s contacts and the willingness of companies to participate, narrowed the search for a suitable case down to a small Dutch company (< 30 people). This company produces in batches, falls under the Dutch Seveso-II directive (BRZO, 1999) and authorized access to the relevant data. The selected company had experienced some serious accidents recently, in spite of using many technical safety systems. Thus the management was aware of the necessity to enhance both safety and the reliability of the operational process. 

Stage 4, the identification of the initial ineffective control element, can only be identified on the operational control level. Due to limited information (in spite of selecting accidents on the basis of information-richness), hierarchical control levels cannot be identified. 

In the previous Chapter it was shown that the developed protocol for analysis identified the ineffective control elements causing the precursors prior to accidents. However, due to the lack of detailed accident information the conclusions were limited. To perform the analysis, using the developed 7-stage protocol pro-actively (before any accident occurs), cases have to be selected on which the analysis can be performed and from which reliable and generic conclusions about safety indicators and the performance of current safety management systems can be obtained. The next sub-Section will discuss the selection criteria to select suitable cases. 

We cannot infer from court decisions whether the underlying legal rules favor the defendant or the plaintiff because legal rules affecf the selection of disputes from the universe of accidents (and nonaccidents) as well as the outcome (Eisenberg 1990). That, in itself, would not be a problem if there were data about people s decisions to litigate and settle but, for the most part, trials are the only window on the liability system... 

This involves considerable art, which must be learned in the clinic. It falls into two divisions (1) surface application to the mucous membranes, especially of the eye, nose, throat, and urethra and (2) injections about nerves, in different parts of their course and distribution, from their spinal roots to their ultimate fibrils. The advantages and disadvantages in comparison with general anesthesia and the selection of the local anesthetic agent also depend on clinical discrimination. Nervous, fearful, and excitable patients often suffer severely from apprehension, which also disposes toward accidents. They may be at least somewhat quieted by sedatives, morphine (0.015 g hypodermically) half an hour before the operation, or by barbiturates. The latter also tend to prevent convulsions. 

Technical solutions relating to selection of the thermal conversion unit design mainly depend on the results of analysis of various accident modes of the selected design, and estimates of diffusion flows (hydrogen flow to primary circuit and tritium flow to process circuit), i.e. on those problems which are connected with validation of possible failure as a result of intermediate circuit application. 

The Chernobyl accident provided the ideal opportunity to study the deposition of radionuclides to vegetation over a wide geographical area, after a single spike release. Table 7-4 shows a selection of data on deposition velocities for 137Cs and 103Ru... 

Hazard Reviews. Formal and informal hazard reviews are essential to establishing an operational history that is free of accidents. Reviews should be made at key points during the selection, design, construction, start-up and operation of a system. Such reviews are cost-effective because they identify hazards and permit problems to be solved before incorrect and... 

Characteristic of several of the selection criteria is that they are reactive. The authority or the inspectors choose themes on the basis of information received from others. They do not analyse information they have collected independently. Tips from other authorities and reports in the media are examples of such criteria. Events and environmental problems in the media are often related to specific serious accidents. It is not unusual for the media itself to act reactively under pressure from stake-holders, interest groups, public authorities and private companies (Asp 1986). From the perspective of environmental efficiency, this kind of selection can be problematic, specifically when environmental problems of lesser importance are chosen for inspection. 

The news media reinforcement is subtle in misconceptions on risk of chemical plants. They provide selected news coverage. No doubt there are many poor unfortunates in southwestern Louisiana who die harvesting shrimp, oysters, blue crabs, pogy fish, and edible fish. Their demise is not a top story. No news reporter takes a photo of the water or the boat that steals the hard worker s life. Or in the case of the timber cutter who perished, no one takes a photo of the tree that struck the deceased or a photo of the chain saw that was involved in the tragic accident. These incidents usually appear in the back of the paper, or only the worker s name, age, next of kin, and personal information get published on the obituary page. 

One of the first issues addressed by the committee was what constitutes a chemical event. The Army s definition of chemical events encompasses all chemical accidents, incidents, and politically and publicly sensitive occurrences (U.S. Army, 1995), whether or not chemical agent was actually present. The committee determined that the seven examples provided in Army Regulation 50-6 (U.S. Army, 1995 see Chapter 1) were too broad for the tasks assigned to it. Consequently, it elected to establish its own criteria to determine which of the reported incidents qualified as chemical events. The following definition was developed by the committee and used for the selection process ... 

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