Flooding causes

A flooding analysis for major plant systems uses a qualitative fault tree that takes into account the elevation of system components. This procedure, illustrated in Figure 5.3-1, uses a fault tree captioned for the top event, "core melt due to internal flood." The fault tree is developed under the assumption that a flood causes a transient, small, or large LOCA, or causes the failure of... 

Flood Cause criticality Unlikely No water in critical facility. 

Figure 1.6 Flooding caused by inadequate downcomer clearance.

Figure 7.10 Flooding caused by mislocation of holddown grid.

Figure 1.1 Flooding caused by Hurricane Katrina destroyed many areas...

All trays must have a balance of downcomer areas. Notice that the areas of the two side downcomers on any tray (straight downcomers, not sloped) are nearly equal area to that of the center downcomer. In other words, the area of the center downcomer tray approximately equals the area of two side downcomers. The logic here is that the liquid backup height in all downcomers must be equal, or otherwise the choked downcomer (the one having a lesser area) will flood, causing tray failure. 

The water regime of the river is characterized by a spring-summer flood caused by snow melt and rainfall and by rainfall floods during the year. The highest water runoff is observed in May. The seasonal water runoff distribution is fairly uniform. The river flow regulation practically did not influence the water runoff. 

The most probable cause of a submarine sinking is flooding caused by an event that breaches the outer hull. The force required would have to be substantial. Potential causes include surface collision, grounding, external explosion, and catastrophic failure of a hull valve. It is likely that such an event also would start a fire within the submarine. The immediate concern for the crew is the release of toxic gases that are produced as the combustion products of on-board fires (U.S. Navy 1998). Human exposure to these gases can lead to adverse health effects, particularly respiratory and central nervous system effects, and even... 

Related Calculations. The velocity calculated above is the threshold for flooding of the condenser. Flooding causes unstable operation. A safety factor of 0.85 is commonly used when designing upflow condensers. The maximum velocity at which flooding occurs can be increased by cutting the bottom of the tube at an angle. Improvements that can be achieved are as follows ... 

Figure 1.5 New Orleans, LA, August 31, 2005—People walk through the New Orleans floodwaters to get to higher ground. New Orleans was under a mandatory evacuation order as a result of flooding caused by Hurricane Katrina.

Tropical rain forests are important in maintaining the balance of CO2 and O2 in the earth s atmosphere. In recent years a portion of the South American forests (by far the world s largest) larger than France has been destroyed, either by flooding caused by hydroelectric dams or by clearing of forest land for agricultural or ranching use. 

Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. Flooding causes major damage to lower floors of all structures near the shoreline. Massive evacuation of residential areas may be required. 

Peace, in the sense of the absence of war, is of little value to someone who is dying of hunger or cold. It will not remove the pain of torture inflicted on a prisoner of conscience, it does not comfort those who have lost their loved ones in floods caused by senseless deforestation in a neighboring country. Peace can only last where human rights are respected, where the people are fed, and where individuals and nations are free."... 

The design procedure sizes the column to prevent flooding caused by excessive entrainment. Flooding can also occur in the downcomers, and this case is discussed later. Excessive entrainment can also cause a large drop in stage efficiency because liquid that has not been separated is mixed with vapor. The effect of entrainment on the Murphree vapor efficiency can be estimated from... 

A third sequence of experiments was done on one core following the flow experiments at residual oil saturation. The core was heated to 60C and polymer flooded at maximum rate using the 1500 ppm solution to reduce the oil saturation and increase brine permeability. Oil displaced by this polymer flood caused the brine permeability to increase from 10 md to about 90 md. Thus, it was possible to conduct polymer flow experiments on a core with the same internal pore configuration but with a different permeability. 

Consistent with the phase equilibrium concept discussed in this section, there was a considerable difference in the time at which surfactant concentration peaked in the effluent liquids from those two chemical floods. Surfactant lag, brought about by the high salinity formation brine in the one flood, caused surfactant concentration in the effluent liquids to peak about 15 percent pore volume later in the flood with 100 percent SDSW formation brine than in the flood with 20 percent SDSW formation brine. 

All data and observations must be recorded in the notebook. Paper towels, napkins, toilet tissue, or scratch paper tend to become lost or destroyed. It is bad laboratory practice to record information on such random and perishable pieces of paper. All entries must be recorded in permanent ink. It can be frustrating to have important information disappear from the notebook because it was recorded in washable ink or pencil and could not survive a flood caused by the student at the next position on the bench. Because you will be using your notebook in the laboratory, the book will probably become soiled or stained by chemicals, filled with scratched-out entries, or even slightly burned. That is expected and is a normal part of laboratory work. 

This Safety Guide does not deal with floods caused by any acts of sabotage on or off the site. 

For a regional analysis where the region includes a coast, a prehminary study of coastal floods should be performed. At the preliminary phase of site selection the most important flood causing events, in particular surges. 

For site assessment at the feasibility and verification stages (i.e. the evaluation of the suitabihty of a site to host a plant), first the large scale and long term weather pattern of the area should be established, then a preliminary evaluation of the important flood causing events for the proposed site should be undertaken. 

It is recognized that floods originating from dam failures could be increased by flood waves due to landshdes into rivers and reservoirs, which could result from severe precipitation. Floods caused by dam failures should generally be combined with an appropriate flood due to other causes (see below) to obtain the controlhng flood. The appropriate coincident wind wave activity (wave set-up and wave runup) should be superimposed on the flood still water level that has been determined. 

In deriving the design basis flood for a nuclear power plant, combined events should be considered as well as single events. Combinations of events should be carefully analysed with account taken of the stochastic and nonlinear nature of the phenomena. Furthermore, the ambient conditions that are relevant for the important flood causing event or for each event of the selected combination should also be taken into account. 

The design basis flood for a given site may result not from the occurrence of one extreme event but from the simultaneous occurrences of more than one severe event each of which is in itself less than the extreme event. The interdependence or independence of the potential flood causing phenomena should be examined according to the site specificity. In many combinations of flood causing events the distinction between dependent and independent events is not sharp. Sequential meteorological events, for example, are only partially dependent on or fuUy independent of each other. In contrast, seismic and wind events are clearly independent. 

The potential for instability of the shoreline, jams of debris and ice effects should be evaluated and if the occurrence of these events affects the flood at the site they should be combined with other primary flood causing events. 

A-1. A suitable combination of flood causing events depends on the specific characteristics of the site and involves considerable engineering judgement. The following is an example of a set of combinations of events that cause floods for use in determining the design conditions for flood defence in an estuary where the following items are of importance ... 

Both lack of water (leading to the deltydration of the membrane) and excess of water (leading to flooding) cause a drop in the cell voltage, which makes it tricky to detect and diagnose the problem. 

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