Accidents, 1957 study

Aluminium chloride was introduced into recovered nitrobenzene containing 5% phenol. This operation led to a violent detonation. A post-accident study showed that, at ambient temperature, the mixture of these three reactants makes the temperature rise and that at a temperature starting at 120 C, the reaction becomes extremely violent. 

Anon., Interim Report. Tanker Accident Study Committee, API, Washington DC, November 1970. 

Marijuana use impairs a person s abihty to form memories, recall events, and shift attention from one thing to another.THC also disrupts coordination and balance by binding to receptors in the cerebellum and basal ganglia. Through its effects on the brain and body, marijuana intoxication can cause accidents. Studies show that approximately 6% to 11% of fatal accident victims test positive for THC. In many of these cases alcohol is detected as well. 

The critical incident technique is regarded as an outgrowth of studies in the Aviation Psychology Program of the U.S. Army and Air Forces in World War 11. It is an accident study method in which an interviewer questions a nnmber of persons who have performed particular jobs and asks them to recall within a specified time period unsafe acts and/or conditions they have committed or observed [p. 303]. 

The nuclides are grouped according to a criterion adopted in many source term (complex of external releases in an accident) studies. This classification takes into account important factors in the release evaluation, such as the volatility of the element or its probable compounds and their chemical/physical properties. 

The most severe hazard caused by hydrogen release is that it will be released, sooner or later according to the conservative assumptions made in severe accident studies, into the primary containment atmosphere where it may cause, in the presence of air, explosions or relatively slow combustion. In both cases, the internal pressure in the primary containment will increase and its integrity will be endangered. The containment safety margins against internal pressure are, however, normally high. ... 

From data like these, stems the practical rule of multiplying the specification value by 10 in correspondence with a 10 per cent probabUity and by 100 for a 1 per cent probability, in a probabUistic accident study. 

Accident studies with the European Accident Code (EAC-2) were continued, but at a reduced pace, for the sodium-cooled 800 MWe fast reactor design used in the European WAC benchmark calculation of 1989. 

GIDAS German In-Depth Accident Study. http //www.gidas.org/files/GIDAS eng.pdf, as of December 22, 2010. 

German In-Depth Accident Study UnfaUdatenbank 07.1999-12.2008. Dresden, Hannover, 31.12.2008. 

The focus is on two data sets in the following analysis the German In-Depth Accident Study (GIDAS) and the Pedestrian Crash Data Smdy (PCDS) from the US. 

The vast majority of situations in the simulation did not result in an accident. The characteristics of simulated accidents as a random result were tested using knowledge from in-depth accident studies such as GIDAS. The simulation used showed adequate validity. 

Accident studies, or hazard analyses, often assume that reactivity is inserted so as to make the reactor supercritical on the prompt neutrons alone. In such events, sufficient power may be generated to cause feedback effects due not only to temperature changes, but also to shock motions or inertial accelerations of reactor parts. A discussion of some of these effects in a detailed accident study is presented by Brooks in his report to the symposium. 

In the 1930s, Heinrich smdied the relative role of unsafe acts and unsafe conditions. He concluded that 88% of cases involved unsafe acts, 10% involved unsafe conditions and 2% had no preventable cause. A different study in the 1960s by the State of Pennsylvania found both unsafe acts and unsafe conditions were causes for nearly every accident studied. The ratio between the two causes is irrelevant. Any ratio does not provide a suitable strategy when analyzing hazards and accident prevention. Preventing accidents must consider both as well as the surrounding circumstances. 

For normal reactor operation, one is interested in temperatures ranging from 500° to 2000°K, and for accident studies temperatures up to 10,000°K and sometimes higher. It is then evident that the isolated resonance approximation is not valid in the upper part of the temperature-energy range, even for U , and is scarcely usable at all for U , with Pu an intermediate case. Since p waves enter significantly only above a few kiloelectron volts, the isolated resonance approximation is not suitable for calculation of the p-wave contribution. 

The difficirlty of extracting GPS-related human machine interaction problems has prevented the identdication of the relevant issues in today s aviatioa The combined incident and accident study presented here shottld distinguish the issues that initially need our atterrtion and may prevent an increase in GPS-related incidents and possible accidents. On the basis of the theory on human/machine interaction and the previous studies on GPS utihzation in aviation, it is expected that incidents and accidents reveal issues of training and system design. Incident analysis should aid in the prevention of accidents, particirlarly since incidents can be considered a precursor of an accident and may develop into an accident without intervention. 

In 1910, the U.S. Bureau of Mines was created by the Department of the Interior to investigate the causes of mine accidents, study health hazards, and find means for taking corrective action. 

Two kinds of causes are taken into account in the database the general cause and the specific cause. Of the 413 accidents studied in this survey, the cause was known only in 252 cases (61% of total). This can be explained by the fact that it can be very difficult to establish the cause after the accident. The various general causes are summarized in Table 41.11. Because one accident can be due to more than one cause, the sum of the percentages is again greater than 100. 

The Nuclear Protection and Safety Institute of the Commissariat a I Energie Atomique (CEA) is conducting a new important experimental program at the Valduc Criticality Laboratory in the field of criticality accident studies, both to provide consistent data for safety analysis and to improve its ability for facing a possible accidental situation. 

Local authority accident studies — most local authorities in the UK produce annual reports on accidents and casualty levels in their areas while some produce reports on the safety performance of features such as roundabouts and traffic signals. 

TecnEcon Report Pilot red route accident study, 1996... 

The steady-state simulation showed that the average reactor core channel operates in sub-cooled forced convection, with the hot core channel is in sub-cooled nucleate boiling. A minimum critical heat flux (CHF) ratio of 7.2 was calculated for the hottest location, indicating a large margin of safety during normal operation. The initial conditions obtained from the analysis of normal operation were used as the initial condition in the accident studies. 

W. Heinrich did his research prior to 1929, only one cause of the accidents studied were considered, which led to the findings that 88% of all accidents are caused by unsafe acts. At the same time of this research, the National Safety Council found that if one looked at both the unsafe acts and the unsafe conditions, they were almost on a par. 

On the basis of Nagel s (1988) information processing stages, 71 per cent of the 284 accidents studied were considered to involve human error, whereby 22 per cent were eoded as information errors, 35 per cent as decision errors, and 43 per cent as action errors (O Hare et al., 1994). However, a different picture emerged when the mishaps were divided according to accident severity. Of the 34 accidents in which there was a fatality or serious injury, 62.5 per cent were attributable to decision errors, while only 25 per eent involved the action stage (O Hare et al., 1994). Of the 169 cases involving minor/non-injury occurrences, only 30.5 per cent were the result of decision errors, while 45.6 per eent were attributed to action errors. These results closely mirror those reported by Jensen and Benel (1977) in their examination of NTSB reeords between 1970 and 1974 in whieh the majority of non-fatal incidents appeared to involve perceptual-motor factors, whereas most fatal accidents were associated with decision-related factors (Jensen and Benel, 1977). 

In a conventional fast reactor the mean energy of neutron absorption is about 100 kilo electron volts (keV). However energies down to about 100 eV are of importance in the calculation of reactor core properties, and a lower energy range can be of importance in some types of accident study (in particular to calculate the effect of the entry of hydrogenous substances into the core). 

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