Aircraft crashes

Reference [2] gives recommendations and guidance for a site specific review of the potential risk of an aircraft crash on the site and the nuclear power plant itself. The result of this analysis, which is based on a screening procedure to identify the potential hazard associated with an aircraft crash, is expressed in terms of either specific parameters for the aircraft (mass, velocity and stiffness) or load-time functions (with associated impact areas). 

In the probabilistic approach for hazard evaluation, this information is complemented by a selected probability limit (value), but it is not to be used in a deterministic design (structural and functional). In the deterministic approach for hazard evaluation, the reference load case may be identified without explicit reference to an aircraft type or to a probability of occurrence. 

SSCs requiring a design for aircraft crash are defined by a safety analysis conducted as specified in Section 2. Section 2 defines the overall safety functions to be performed by the plant. Alternative paths may be selected to achieve satisfactory performance of these functions. Iterations between the designers of the SSCs may occur before the final EE classification of the SSCs is determined. 

All SSCs classified as EE-Cl, EE-C2 and EE-C3 should be designed or evaluated for the aircraft crash event. In some cases and for some phenomena, such as overall aircraft impact, selected structures may be shielded by other structures designed to resist the aircraft crash. For these cases, the shielded structure may not need to be assessed with respect to direct impact. 

Wind induced missiles usually generate effects of the same nature as those of aircraft crashes, but smaller. Reference [2] discusses such enveloping 

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Appendix HI, of WASH-1400 presents a database from 52 references that were used in the study. It includes raw data, notes on test and maintenance time and frequency, human-reliability estimates, aircraft-crash probabilities, frequency of initiating events, and information on common-cause failures. Using this information, it assesses the range for each failure rate. 

Appendix III contains failure rate estimates for various genetic types of mechanical and electrical equipment. Included ate listings of failure rates with range estimates for specified component failure modes, demand probabilities, and times to maintain repair. It also contains some discussion on such special topics as human errors, aircraft crash probabilities, loss of electric power, and pipe breaks. Appendix III contains a great deal of general information of use to analysts on the methodology of data assessment for PRA. 

The incidence of aircraft impacts may be significantly higher in certain areas (e g., in the vicinity or airports). The aircraft crash hazard is site specific and tlie failure is strongly dependent on the kinetic energy of tlie aircraft. Two types of data are needed to analyze for aircraft impact the aircraft crash rate in tlie site vicinity (per unit area per year) and tlie effective target area of tlie vulnerable item. Crash rates for different categories of aircraft can be obtained from state and national autliorities (e.g., FAA). The proximity of the site to airfields must be taken into account because crashes are much more frequent witliin a radius of approximately 3 miles. 

In 1977, two fully loaded Boeing 747 commercial aircraft crashed into each other on a foggy runway in the Canary Islands. This accident was then the worst in aviation history and took 583 lives. An inquiry concluded most of the deaths in the Canary Islands accident resulted from the aviation fuel fire that lasted for more than 10 hours. G. Daniel Brewer, who was the hydrogen program manager for Lockheed, stated that if both aircraft had been using liquid hydrogen as fuel instead of kerosene, hun-... 

As a coating offers increased anti-icing effectiveness and durability than fluorocarbon and silicone elastomers. These icephobic coats can reduce the accumulation of ice on products such as rooftops, aircraft, radomes, antennas, ships, and power-transmission lines. The weight of such accumulations of ice has led to aircraft crashes, fallen power lines, etc. The icephobic coats reduce the adhesive force between ice and a surface. Polyphosphazene elastomers possess these desired properties, in addition have low glass transition temperature (Tg), good environmental stability, curability, and moderate cost. 

Other factors (forced evacuation for environmental hazards, aircraft crashes)... 

The QRA includes all identified potential causes of release, except for intentional acts, such as sabotage and terrorism. Releases resulting from both internal initiating events (events that originate inside the facility or that result directly from activities during the disposal process) and external events (such as earthquakes, aircraft crashes, and tornadoes) are included. 

The safety philosophy for future nuclear plants will most probably include the protection against aircraft crash (penetration and induced vibrations) as well as chemical explosion waves such that a respective contribution to the risk is minimal. 

If corrosion is the cause of an aircraft crash into the sea, the costs are effectively, partly internalized as the airlines obtain their money for anticorrosion measures from fare-paying passengers. However, if the aircraft crashes on a city suburb, third parties are involved, and the costs are externalized. Internalized costs represent an argument for industry support for corrosion information and dissemination and research facilities. Externalized costs refer to government support. 

A problem discovered by an air force corrosion engineer was the corrosion of tin-plated electrical connector pins mated with gold-plated sockets. Fretting corrosion between these very small contacts appears to have been implicated in as many as six F-16 fighter aircraft crashes when their main fuel shutoff valves closed uncommanded (17). 

The F-16 fighter aircraft crashes and the Aloha incident described earlier are good examples of documented corrosion-related failures. Now we turn our attention to some corrosion-related accidents involving great loss of life. 

The design of safe, crashworthy subfloor structures is dependent on crash severity and what is considered to be a survivable crash. For large civil transport aircraft, crash-worthiness requirements are set out in CFR and CS paragraphs 25.561, 25.562, [3,4],... 

Desjardins SP, Zimmermann RE, Bolukbasi AO, Merritt NA. ACSDG aircraft crash survival design guide, vol. I—IV December 1989. USAAVSCOM TR 89-D-22A-E. 

MIL-STD-1290A (AV) Mihtary standard for light fixed and rotary-wing aircraft crash resistance. Washington, DC Department of Defense September 1988. 

An example of an accident that has been attributed to an indirect mode change occurred while an A320 was landing in Bangalore, India [182], The pilot s selection of a lower altitude while the automation was in the altitude acquisition mode resulted in the activation of the open descent mode, where speed is controlled only by the pitch of the aircraft and the throttles go to idle. In that mode, the automation ignores any preprogrammed altitude constraints. To maintain pilot-selected speed without power, the automation had to use an excessive rate of descent, which led to the aircraft crashing short of the runway. 

In addition to operational accidents, external accidents also require detailed study. Examples are earthquake, extreme wind, flooding, aircraft crash, external fire, etc. Because of the time limit, the details will not be discussed here. 

Furthennore the impact of external events such as earthquakes, aircraft crash, tornado, flooding or pressure waves (possibly resulting from events in neighbouring plants or transportation routes) have to be accounted for as initiating events or events triggering initiating events. 

Possible external events are fires, flooding lightning, storm, earthquake, explosion, aircraft crash etc. They will usually affect several components at the same time. 

Steel and reinforced concrete beams have a classical advantage over timber beams because, unlike standard timber beams, they exhibit ductile behaviour which can lead to a favourable redistribution of loads in multi-span beams. This behaviour enhances beam performance in extreme loading cases like earthquakes or an aircraft crash into a building. Our calculations indicate that if the flexible adhesive layer is placed in the top part of a glulam beam over the intermediate support of a multi-span beam (Fig. 18), the reduced stiffness in this section could also lead to... 

Number 1 engine then burst into flames and the aircraft crashed. Of the 126 people aboard, 47 died and 74 sustained serious injuries. 

The preceding evaluations, despite the high level of protection already incorporated in the casks, support the need for technological solutions which offer special protection against aircraft crash and against explosive events or solutions such as where the storage structure is located at least 20 m below grormd level. 

In certain cases it may not be necessary to consider the combination of an event or hazard with a single faUure when the probability of the combination is very low (e.g. aircraft crash). 

Potential man-made threats include aircraft crashes, chemical/toxlc gas releases, forest fires, loss of electrical power, soil erosion, criticality events, explosions, missiles, pipeline accidents, structural interactions, and transportation accidents. These events and their potential effects on the HCF are discussed in Chapter 3. 

Fire (radiological and toxic material) Forklift fire incident causes transfer cask breach with possible target exposure and airborne release Failure of electrical equipment or system in SCBs, SGB, ventilation hood, Zone 2 or Zone 2A canyon Lightning strike External fire (vehicle accident, aircraft crash, other building fire) irradiated isotope production target, up to 20,000 curies. Volatiles in process cold traps, up to 70,000 curies. Same material as toxic spill. Residual radiological contamination. 

External fire (vehicle accident aircraft crash, other building fire) (App. 3B) IV D 4... 

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