Saturday, October 31, 2009

Chernobyl Nuclear Power Plant Accident Article

Location of Chernobyl Nuclear Power Plant Accident

On April 26, 1986, at 1:23 a.m. local time, reactor number four at the Chernobyl Nuclear Power Plant in the Soviet Union exploded. Additional explosions and the resulting fire sent a plume of radioactive fallout into the atmosphere. The fallout released was four hundred times more than had been released by the atomic bombing of Hiroshima.

The plume drifted over extensive parts of:

  • Western Soviet Union
  • Western Europe
  • Eastern Europe
  • Northern Europe
  • Eastern North America

Large areas of Russia, Belarus, and the Ukraine were badly contaminated. The contamination resulted in the evacuation of over 300,000 people. About 60% of the radioactive fallout landed in Belarus.

It was the worst nuclear power plant disaster ever, resulting in a severe release of radioactivity into the environment. Two people died in the initial steam explosion, but most deaths from the accident were attributed to radiation.

Russia, the Ukraine, and Belarus are still dealing with the continuing decontamination and health care costs of the Chernobyl accident.

The cost of the disaster is estimated to be around $200 billion USD, making Chernobyl the costliest disaster in modern history.

According to the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO), 56 direct deaths and an estimated 4,000 extra cancer deaths have been attributed to the disaster.

The Chernobyl Exclusion Zone and other limited areas remain off limits. The majority of affected areas are now considered safe for economic activity and settlement.

The Accident

The accident occurred on April 26, 1986, when reactor four suffered a massive, catastrophic power excursion. This resulted in a steam explosion, tearing the top from the reactor, exposing the core, and dispersing large amounts of radioactive particulate and gaseous debris (mostly Strontium-90 and Cesium-137). This allowed oxygen to contact the hot core, which contained 1,700 tons of combustible graphite moderator. The burning graphite moderator increased the emission of the radioactive particles.

The radioactivity was not contained by any type of containment vessel, and radioactive particles were carried by the wind across international borders.

Crisis Management

Radiation Levels

The radiation levels in the worst-hit areas of the reactor building are estimated to have been 5.6 rontgen per second (R/s), or 20,000 R/hr. A lethal dose is around 500 rontgen over 5 hours; some workers received fatal doses within several minutes.

Due to faulty dosimeters (equipment to measure rontgens) or dosimeters which only read low levels of rontogens, the reactor crew chief assumed that the reactor was intact. Operating under this assumption, the chief and his crew stayed in the reactor building until morning trying to pump water into the reactor.

None wore protective gear, and most died from radiation exposure within three weeks.

Fire Containment

Shortly after the accident, firefighters arrived to try to extinguish the fire. They were not told how dangerous the smoke and debris were. They were not told that the fire involved the reactor.

The fires were extinguished by 5 a.m., but many firefighters received high doses of radiation. The fire inside reactor no. 4 continued to burn until May 10, 1986. It was finally extinguished by dropping tons of sand, lead, and clay onto the burning reactor and injecting liquid nitrogen.

Causes of the Disaster

There were two official explanations of the accident:

  • Flawed operators explanation
    Placed the blame on the power plant operators
  • Flawed design explanation
    Placed the blame on flaws in the reactor design, especially the control rods

Effects of the Disaster

  • International spread of radioactivity
  • Radioactive release
  • Human cost
    237 people suffered from acute radiation sickness
    31 died within the first 3 months after the disaster
    135,000 evacuated from the area
  • Environmental costs
    Radioactive contamination of aquatic systems
    Four square kilometers of pine forest in the immediate vicinity of the reactor turned brown and died
    Some animals in the worst-hit areas died or stopped reproducing

Chernobyl After the Disaster

All work on the unfinished reactors at Chernobyl halted in 1989. A fire broke out in reactor 2 in 1991, resulting in it being taken off-line. Reactor 1 was decommissioned in 1996. Reactor 3 was turned off in 2000, effectively shutting down the entire plant.

Disaster's Effect on Human Health

· 57 direct deaths in the accident itself

· 4,000 additional cancer cases due to the accident

· Primarily thyroid cancer

· No increase in the rate of birth defects or abnormalities

· No increase in solid cancers

· Possibility of tens of thousands of cases of thyroid cancer in the future.

source: abovetopsecret

old articles: chernobyl nuclear power plant disaster

Tuesday, October 20, 2009

Video of How Hydroelectric Power Works

Video of How Hydroelectric Power Works

Hydroelectricity energy is a renewable energy source dependent upon the hydrologic cycle of water, which involves evaporation, precipitation and the flow of water due to gravity. Canada has abundant water resources and a geography that provides many opportunities to produce low-cost energy. In fact, accessing the energy from flowing waters has played an important role in the economic and social development of Canada for the past three centuries.

Source: Hydroelectricity Power Works

Tuesday, October 13, 2009

What is hydroelectricity according to wikipedia?

The World Largest Hydroelectricity Three George Dam

Hydroelectricity is electricity generated by hydropower, i.e., the production of power through use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the greenhouse gas carbon dioxide (CO2) than fossil fuel powered energy plants. Worldwide, hydroelectricity supplied an estimated 816 GWe in 2005. This was approximately 20% of the world's electricity, and accounted for about 88% of electricity from renewable sources.


Sunday, October 11, 2009

Hydroelectricity - source from thecanadianencyclopedia

Hydroelectricity is obtained from the energy contained in falling water; it is a renewable, comparatively nonpolluting energy source and Canada's largest source of electric power generation. In N America in the 1850s the energy content of moving water was exploited through the use of small-capacity waterwheels and turbines for the direct drive of machinery, for example, in gristmills and sawmills. By the 1860s many hundreds of turbines, ranging up to 1000 HP capacity, were manufactured annually in the US and by the early 1870s the production of at least one Canadian factory was averaging about 20 machines per year. Hydroelectricity was introduced in the 1880s, soon after Thomas Edison began manufacturing direct-current (DC) electric generators, which were initially belt driven by steam engines. It was not long before enterprising mill owners began to install generators of up to 10-12 kW capacity, with belt drives from existing mill turbines, to provide electric lighting in the mills and adjacent premises.

Source from thecanadianencyclopedia.

Friday, October 9, 2009

Hydroelectricity Explained

Hydroelectricity is another term for power generated by harnessing the power of moving water. Not necessarily falling water, just moving water. There are many famous such generating stations in the world, not the least of them at Niagara Falls, Grand Coulee and Boulder Dam. These are just a few of the many examples of energy produced by falling water. On the other hand, a small mill set in the rapids of a fast-moving stream is also an example of it in action, on a lesser scale. The truth is that any steady current of flowing water from a river or other waterway can be converted to power.

Source: Hydroelectricity Explained

Wednesday, October 7, 2009

What is Coal Ash?

What is Coal Ash?

Coal combustion byproducts (CCBs) are considered to be four distinct and extremely different materials.


Fly ash is the finest of coal ash particles. It is called "fly" ash because it is transported from the combustion chamber by exhaust gases. Fly ash is the fine powder formed from the mineral matter in coal, consisting of the noncombustible matter in coal plus a small amount of carbon that remains from incomplete combustion. Fly ash is generally light tan in color and consists mostly of silt-sized and clay-sized glassy spheres. This gives fly ash a consistency somewhat like talcum powder. Properties of fly ash vary significantly with coal composition and plant-operating conditions.

Fly ash can be referred to as either cementitious or pozzolanic. A cementitious material is one that hardens when mixed with water. A pozzolanic material will also harden with water but only after activation with an alkaline substance such as lime. These cementitious and pozzolanic properties are what make some fly ashes useful for cement replacement in concrete and many other building applications.


Coal bottom ash and fly ash are quite different physically, mineralogically, and chemically. Bottom ash is a coarse, granular, incombustible byproduct that is collected from the bottom of furnaces that burn coal for the generation of steam, the production of electric power, or both. Bottom ash is coarser than fly ash, with grain sizes spanning from fine sand to fine gravel. The type of byproduct produced depends on the type of furnace used to burn the coal.


Boiler slag is coarser than conventional fly ash and is formed in cyclone boilers, which produce a molten ash that is cooled with water. Boiler slag is generally a black granular material with numerous engineering uses.


Flue gas desulfurization (FGD) gypsum is also known as scrubber gypsum. FGD gypsum is the byproduct of an air pollution control system that removes sulfur from the flue gas in calcium-based scrubbing systems. It is produced by employing forced oxidation in the scrubber and is composed mostly of calcium sulfate. FGD gypsum is most commonly used for agricultural purposes and for wallboard production.

More details: What is coal ash? (source)

Saturday, October 3, 2009

Video - How a coal power station works?

Video - How a coal power station works?

Coal shipment from coal jetty transfered to the coal stockyard. There is a large machine called stacker reclaimer, arranged the coal into the storage piles. A series of conveyor belt transport the coal to the generating plant where it goes to the bunker hopper for temporary storage before it was introduced to bowl milling. Coal will be pulverized or; coal is grinded to a fine powder more less 70 microns prior to burning. The pulverized coal is mix with air and is feeded to the furnace combustion that is surrounding by boiler tube filled with purified water. The burning coal heats the purified water inside the boiler tube to the steam. The steam is transfered under high pressure and high speed throughout the pipe turbine. This pressure flow pushes the blade of turbine to spin. Turbine is connected to the generator where the spinning of the turbine will causes a shaft to turn inside generator and create electricity. The producing of the electricity that can be step up voltage through the station transformer and send from the station across transmission line. The steam from the turbine (exhausted) condense back to the purified water using cooling water from the forebay or seawater and pump back to the boiler where it's reheated back to continue the process again.

How a coal-fired power plant works
General coal-fired power plant view

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