Friday, April 22, 2011

How much safe is Nuclear Power Plant?

Increase in the number of reactors will increase the the possibility of exposure to radiation hazards.
Dr. Nitish Priyadarshi

Japan has raised its assessment of the accident at the crippled Fukushima Daiichi nuclear power plant to the worst rating on an international scale, putting the disaster on par with the 1986 Chernobyl explosion.

The decision to raise the alert level to 7 from 5 on the scale amounts to an admission that the accident at the nuclear facility, is likely to have substantial and long lasting consequences for health and for the environment.

Living with radiation can in fact be frightening. Plants making nuclear-weapons materials also pollute our environment. Three Mile Island and Chernobyl, as well as other nuclear power plant accidents, have alarmed us. Nuclear waste is piling up.

What is radiation anyway? Although the term is broad enough to include sunlight and heat, radio waves and microwaves, it is most often used to mean ionizing radiation. Every radioactive substance contains unstable atoms, or radionuclides. They want to become something else- something stable- so they change or decay. With each change energy is released. A radionuclide may transform itself many times before becoming stable. An atom of radioactive uranium 238 goes through 14 changes before stabilizing as lead 206. These sequences are known as decay chains.

If body tissues and cells become ionized, abnormalities in DNA can result. Cancer and birth defects can also result from exposure to ionizing radiation.

Even more than Three Mile Island, the explosion at the Chernobyl power plant in soviet Ukraine confirmed the worst nuclear fears. Poor design magnified operator negligence to cause disaster. The explosion sent the graphite slabs of the reactor core through the roof, setting it afire and spewing radioactive materials around the world. Twenty percent of the plant’s radioactive iodine escaped, along with 10 to 20 percent of its radioactive cesium. Thirty persons died; 237 suffered severe radioactive injury. Chernobyl affected the health of many people throughout Russia. Around 600,000 were classified as being ‘significantly exposed’ and will have their health monitored their whole lives.

The main economic cost of the Chernobyl explosion was from the effect the fallout had on the agriculture. Enormous amount of milk in Poland, Hungary, Austria and Sweden were made unusable by the contamination from radioiodine and radioiodine and radiocesium. Also many countries across Europe had numerous amounts of vegetation burned because of contamination. A ban on many agricultural goods was placed in Eastern Europe. The longest effect the radiation had was on the reindeer and sheep in Sweden.

The Three Mile Island accident was a core meltdown in Unit 2 (a pressurized water reactor ) of the Three Mile Island Nuclear Generating Station in Dauphin County, Pennsylvania near Harrisburg, United States in 1979.

The power plant was owned and operated by General Public Utilities and Metropolitan Edison. It was the most significant accident in the history of the USA commercial nuclear power generating industry, resulting in the release of up to 481 P Bq (13 million curies) of radioactive gases, and less than 740 GBq (20 curies) of iodine-131.

On December 12, 1952 a partial meltdown of a reactor's uranium core at the Chalk River plant near Ottawa, Canada, resulted after the accidental removal of four control rods. Although millions of gallons of radioactive water poured into the reactor, there were no injuries.

On October 1957 fire destroyed the core of a plutonium-producing reactor at Britain's Windscale nuclear complex - since renamed Sellafield - sending clouds of radioactivity into the atmosphere. An official report said the leaked radiation could have caused dozens of cancer deaths in the vicinity of Liverpool.

Other accident took place on Winter 1957-'58 when a serious accident occurred during the winter of 1957-58 near the town of Kyshtym in the Urals. A Russian scientist who first reported the disaster estimated that hundreds died from radiation sickness.

On January 1,1992 four tons of heavy water spilt at Rajasthan nuclear power plant (India).

Lots more are there to be listed.

Fears of radiation hazards from nuclear energy arise on the following counts:

  1. release of radioactivity into the atmosphere.
  2. doubts on safety of operating nuclear reactors and associated health risks.
  3. management and safe disposal of radioactive waste.
  4. possibilities of nuclear plant accidents including sabotage.
  5. risk of proliferation of nuclear weapons.

Nuclear power plants are subject to a number of hazards that may originate from outside. Among natural hazards are earthquakes, flooding of the site, ground settlement, etc. Other hazards could be accidents in near by industries, fire, aircraft crash, or sabotage such as bombing and missile attacks during war and terrorist activities.

Accidents in nuclear power plants in the past have been attributed mainly to operation errors, design deficiencies and a series of equipments failures. But the accident in Japan is the first case due to earthquake.

Controversies regarding actual number of deaths, the quantity of radioactivity released and delayed effects still persist.

The demand for energy in several countries is being substantially met through nuclear reactors. It is feared that the phenomenal increase in the number of reactors during the last 40 years or so has increased the possibility of exposure to radiation hazards and accidents.