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Posts Tagged ‘Chernobyl nuclear disaster’

Pripyat: 16 Years a City, 30 Years a Ghost Town

Posted by feww on April 26, 2016

30th Anniversary of Chernobyl Nuclear Disaster

Pripyat was founded on 4 February 1970 to serve the nearby Chernobyl Nuclear Power Plant. By the time it was evacuated, on April 27, 1986, the day after the Chernobyl disaster, the ninth nuclear city in the Soviet Union had a population of about 49,400.

Chernobyl NPP, [The V. I. Lenin Nuclear Power Station] was commissioned in 1970. The first reactor came online in 1977, followed by Reactor No. 2 (1978), No. 3 (1981), and No. 4 (1983). Between them, the four reactors were producing about 10 percent of Ukraine’s electricity before the core meltdown.

A power surge blew the roof off the reactor No. 4, releasing radioactive clouds across Eastern Europe, and leaving entire regions in three countries—Ukraine, Russia and Belarus—unlivable.

The explosion has so far claimed at least a million lives, and counting.

z-chernobyl-meltdown
Ukraine’s Chernobyl nuclear power plant underwent a core meltdown [center] in 1986 with disastrous consequences. The radionuclide levels still exceed the normal background in 60 Ukrainian towns and villages. This image was taken by authorities in the former Soviet Union.

The radiation contaminated 50,000 square kilometers of land across 12 regions in Ukraine, and forced hundreds of villages to be relocated. In neighboring Belarus 20 percent of the entire country’s land area was also contaminated.

The radionuclide levels still exceed the normal background in 60 Ukrainian towns and villages.

Today, a second casing is being built to contain the radiation, which is still being emitted by the reactor because the old sarcophagus is crumbling.

Never Ending Nightmare at

“In mid-February [2013,] a 600-square-meter section of the roof at the Chernobyl site collapsed, sparking fears of another disaster. The collapse occurred 70 meters above the sarcophagus that contains the radiation from the damaged No. 4 reactor,” said a report.

Experts estimate that 200 tons of radioactive corium [a molten, lava-like mixture of nuclear reactor core materials, containing nuclear fuel, fission products, control rods, structural materials and other substances found in a reactor core,] several dozen tons of highly contaminated dust and 16 tons of uranium and plutonium remain under the existing sarcophagus that covers the disaster stricken power plant.


Birth defects and cancer were the norm for many years following the Chernobyl disaster.  By the time  residents of Pripyat were ordered to evacuate, about two days after the Chernobyl core meltdown had occurred, many had already been exposed to varying doses of radiation poisoning.

1 Million Killed in Chernobyl Disaster

“A report by Alexey Yablokov, Vassily Nesterenko and Alexey Nesterenko which appeared in the Annals of the New York Academy of Science showed that by 2004, there were 985,000 additional deaths worldwide caused by the nuclear disaster, including 212,000 of within Western Russia, Belarus and Ukraine.”

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29th Anniversary of Chernobyl NPP Disaster

Posted by feww on April 26, 2015

Chernobyl sarcophagus falling apart

29 Years ago today (April 26, 1986) a power surge blew the roof off the reactor No. 4 of the V.I. Lenin Nuclear Power Station, as it was then called, releasing radioactive clouds across Eastern Europe, and leaving entire regions in three countries—Ukraine, Russia and Belarus—unlivable.

The explosion has so far claimed at least a million lives, and counting.

z-chernobyl-meltdown
Ukraine’s Chernobyl nuclear power plant underwent a core meltdown [center] in 1986 with disastrous consequences. The radionuclide levels still exceed the normal background in 60 Ukrainian towns and villages. This image was taken by authorities in the former Soviet Union.

The radiation contaminated 50,000 square kilometers of land across 12 regions in Ukraine, and forced hundreds of villages to be relocated. In neighboring Belarus 20 percent of the entire country’s land area was also contaminated.

The radionuclide levels still exceed the normal background in 60 Ukrainian towns and villages.

Today, a second casing is being built to contain the radiation, which is still being emitted by the reactor because the old sarcophagus is crumbling.

However, the dire economic situation in Ukraine may mean the project may be shelved, said a report.

Never Ending Nightmare at

“In mid-February [2013,] a 600-square-meter section of the roof at the Chernobyl site collapsed, sparking fears of another disaster. The collapse occurred 70 meters above the sarcophagus that contains the radiation from the damaged No. 4 reactor.” Said a report.

Experts estimate that 190 tons of reactor fuel remain under the existing sarcophagus that covers the disaster stricken power plant.


Birth defects and cancer were the norm for many years following the Chernobyl disaster.  By the time  residents of Pripyat, a town located near the plant, were ordered to evacuate, about two days after the Chernobyl core meltdown had occurred, many had already been exposed to varying doses of radiation poisoning.

1 Million Killed in Chernobyl Disaster

“A report by Alexey Yablokov, Vassily Nesterenko and Alexey Nesterenko which appeared in the Annals of the New York Academy of Science showed that by 2004, there were 985,000 additional deaths worldwide caused by the nuclear disaster, including 212,000 of them within Western Russia, Belarus and Ukraine.”

Chernobyl fallout covers the entire Northern Hemisphere

Consequences of the Catastrophe. Authors  Alexey Yablokov (Center for Russian Environmental Policy in Moscow), Vassily Nesterenko and Alexey Nesterenko ( Institute of Radiation Safety, Minsk, Belarus) studies about 5,000 reports and scientific  papers mostly published in Slavic languages and compiled their finding in the  book “Chernobyl: Consequences of the Catastrophe for People and the Environment,” which was published last year on the 24th anniversary of the Chernobyl reactor core meltdown.

“For the past 23 years, it has been clear that there is a danger greater than nuclear weapons concealed within nuclear power. Emissions from this one reactor exceeded a hundred-fold the radioactive contamination of the bombs dropped on Hiroshima and Nagasaki.” They wrote.

“No citizen of any country can be assured that he or she can be protected from radioactive contamination. One nuclear reactor can pollute half the globe,” the authors said. “Chernobyl fallout covers the entire Northern Hemisphere.”

According to the book, a total of about 830,000 people, referred to as the “liquidators,” were responsible for various emergency works at the Chernobyl site including fire extinguishing, decontamination and cleanup.

The authors say between 112,000 and 125,000 of the  liquidators had died by 2005.  The authors also estimate that between 1986 and 2004 some 985,000 people died as a result of Chernobyl fallout {2011 estimates are well over a million deaths.]

“Official discussions from the International Atomic Energy Agency and associated United Nations’ agencies (e.g. the Chernobyl Forum reports) have largely downplayed or ignored many of the findings reported in the Eastern European scientific literature and consequently have erred by not including these assessments.” The authors said last year.

What Happened to Wildlife?

Researchers found that there were “areas with an abundance of 100 animals per square meter. And then there are areas with less than one specimen per square meter on average; the same goes for all groups of species.”

The researchers also found that animals living near the Chernobyl reactor were subject to more incidences of deformities, including discoloration and stunted limbs, than normal.

“We wanted to ask the question: Are there more or fewer animals in the contaminated areas? Clearly there were fewer,” said Moller, one of the researchers who has worked on Chernobyl since 1991.

Effects of Chernobyl radioactive contamination on decomposition of plant material

A new study has found that the microbial communities, which are responsible for natural cycle of decay of organic materials,  have been significantly reduced in radioactively contaminated zones near Chernobyl.

The following is Abstract from  the report E-pubulished on March 4,  2014.

Highly reduced mass loss rates and increased litter layer in radioactively contaminated areas

The effects of radioactive contamination from Chernobyl on decomposition of plant material still remain unknown. We predicted that decomposition rate would be reduced in the most contaminated sites due to an absence or reduced densities of soil invertebrates. If microorganisms were the main agents responsible for decomposition, exclusion of large soil invertebrates should not affect decomposition. In September 2007 we deposited 572 bags with uncontaminated dry leaf litter from four species of trees in the leaf litter layer at 20 forest sites around Chernobyl that varied in background radiation by more than a factor 2,600. Approximately one quarter of these bags were made of a fine mesh that prevented access to litter by soil invertebrates. These bags were retrieved in June 2008, dried and weighed to estimate litter mass loss. Litter mass loss was 40 % lower in the most contaminated sites relative to sites with a normal background radiation level for Ukraine. Similar reductions in litter mass loss were estimated for individual litter bags, litter bags at different sites, and differences between litter bags at pairs of neighboring sites differing in level of radioactive contamination. Litter mass loss was slightly greater in the presence of large soil invertebrates than in their absence. The thickness of the forest floor increased with the level of radiation and decreased with proportional loss of mass from all litter bags. These findings suggest that radioactive contamination has reduced the rate of litter mass loss, increased accumulation of litter, and affected growth conditions for plants.

Oecologia. 2014 May;175(1):429-37. doi: 10.1007/s00442-014-2908-8. Epub 2014 Mar. Authors: Mousseau TA(1), Milinevsky G, Kenney-Hunt J, Møller AP. PMID: 24590204 [PubMed – in process]

Chernobyl and Other Nuclear Stats

  • More than 95% of the radioactive material (180 metric tons with a radioactivity of about 18 million curies) still remains inside the Chernobyl reactor.
  • The  core meltdown at Chernobyl was said to have released radiation estimated at 50 million curies. Committee on the Safety of Nuclear Installations said in 1995 that the meltdown had released about 140 million curies. [Researchers Alexey Yablokov, Vassily Nesterenko and Alexey Nesterenko say the radiation released from Chernobyl may have been up to 10 billion curies. In comparison, the Hiroshima bomb released about 3 million curies.]
  • Immediately after the accident, 237 people suffered from acute radiation sickness, and 31 died within the first 90 days of the disaster.
  • About 135,000 people were evacuated from the area surrounding the plant, including 50,000 from the town of Pripyat.
  • The Academy’s  estimate for the number of casualties  are more than 90,000 deaths and more than a quarter of a million cancer cases.
  • The Ukrainian National Commission for Radiation Protection calculates the number of radiation casualties at half a million  deaths so far.
  • In a book published by the New York Academy of Sciences last year on the 24th anniversary of the reactor core meltdown, the researchers maintain that about one million people have died from exposure to radiation released by the Chernobyl reactor so far [as of 2010.]
  • “In the former Soviet Union at least 9 million people have been effected by the accident; 2.5 million in Belarus; 3.5 million in Ukraine; and 3 million in Russia. In total over 160 000 Km2 are contaminated in the three republics.” source
  • Some 441 commercial nuclear power reactors are  operating in 31 countries ( total capacity of 376 gigawatts) each of which is potentially as lethal as Chernobyl, if not worse. [This item, updated here, was written before the Fukushima nuclear disaster began unfolding.]
  • An estimated 56 countries operate more than 250 research reactors.
  • At least 220 nuclear reactors power military ships and submarines.

Legacy: More than 4,000 cases of thyroid cancer were diagnosed among children and adolescents between 1992 to 2002 in Belarus, Russia and Ukraine. Victims under 14 years were most severely affected by the elevated concentrations of radioiodine found in milk.

  • Incidents of skin lesions, respiratory ailments, infertility and birth defects were readily found among the more than five million people who inhabit the affected areas of Belarus, Russia, and Ukraine for many years following the accident.

The Poisoned land. Up to 5 million people continue to live on radioactive contaminated land. About 85% of the children who live in contaminated areas of Belarus today are ill, a near 6-fold increase compared to the time before the explosion (15%), according to The Belarusian National Academy of Sciences.




Birth defects and cancer were the norm for many years following the Chernobyl disaster.  By the time  residents of Pripyat, a town located near the plant, were ordered to evacuate, about two days after the Chernobyl core meltdown had occurred, many had already been exposed to varying doses of radiation poisoning

Fukushima NPP

Fukushima NPP is said to contain about 4,277 tons of nuclear fuel, about 24 times as much as Chernobyl (~ 180 tons).

“The Fukushima Dai-ichi site has a considerable number of fuel rods on hand, according to information provided Thursday by Toyko Electric Power Co., which owns the atomic complex: There are 3,400 tons of fuel in seven spent fuel pools within the six-reactor plant, including one joint pool storing very old fuel from units 3 and 4. There are 877 tons in five of the reactor cores. Officials have said that the fuel in Unit 4′s reactor vessel was transferred to its spent fuel pool when the unit was temporarily shut in November.” AP reported.

On April 12, Japanese authorities raised the measure of severity of the Fukushima NPP disaster to the maximum level of 7 on INES. (See below for details.)

The International Nuclear and Radiological Event Scale (INES)

The INES, a logarithmic scale, which was introduced in 1990 by the IAEA to enable prompt communication, classifies the intensity of nuclear incidents as follows:

7 – Major Accident [Chernobyl disaster, criticality accident, April 1986]

6 – Serious Accident [e.g., Kyshtym incident, Mayak, former Soviet Union, steam explosion released up to 80 tons of highly radioactive material into the atmosphere, September 1957. ]

5 – Accident With Wider Consequences [e.g., Three Mile Island accident  Pen State, U.S., partial meltdown release radioactive gases  into the environment, March 1979.]

4 – Accident With Local Consequences [e.g., Sellafield, UK, at least 5 incidents reported between 1955 to 1979]

3 – Serious Incident [e.g., Vandellos NPP, Spain, fire destroyed control systems; the reactor was shut down, July1989]

2 – Incident [e.g., Forsmark NPP, Sweden, a backup generator failed, July 2006]

1 – Anomaly [e.g., TNPC, France, 1,600 gallons of water containing 75 kilograms (170 lb) of uranium leaked into the environment,  July 2008]

0 – Deviation (No Safety Significance) — [e.g., Atucha, Argentina – Reactor shutdown caused by tritium increase in reactor encasement, December 2006.]

What is a lethal dose of radiation from a single Exposure?

Studies of the 1945 atomic bombing at Hiroshima and Nagasaki show that 100 percent of victims whose bodies were exposed to 600,000 millirems (6,000 mSv) died from radiation. About 50 percent of victims who received  450,000 millirems (4,500 mSv) of radiation also died.

(Note: Rem is a unit of ionizing radiation equal to the amount that produces the same damage to humans as one roentgen of high-voltage x-rays.  Source: MIT)

1 rem = 10 mSv  (1 Sv = 100 rem)

Background Radiation in millirems per year (mrem/yr)

  • Average background radiation (US):  300
  • Higher altitudes (e.g, Denver): 400

“Safe Levels” of Radiation (U.S.)

Limits above natural background radiation levels (average 300 millirems per year) and medical radiation:

  • Occupation Limit: Maximum of 5,000  (the limit for a worker using radiation)
  • Average Natural Background: 300

[Note: Lifetime cumulative exposure should be limited to a person’s age multiplied by 1,000 millirems, e.g., a 70-year-old person, 70,000 millirems.]

Adults

  • Max single dose for an adult: 3,000
  • Annual total dose: 5,000

Under 18

  • Max single dose for a person aged under 18 years: 300 millirems (whole body equivalent)
  • Annual total exposure: 500

Fetal Exposure

  • Maximum limit for fetal exposure during gestation period:  50 millirems per month above background levels

Medical

  • Single Chest X-ray (the whole body equivalent): 2 millirem

Air Travel

  • Coast-to-coast US round trip flight: 12 millirems

*Note:  Radiation dose of about 2,000 millisieverts (200,000 millirems) cause serious illness.

Half-life of some radioactive elements

[NOTE: Half-life is the time taken for a radioactive substance to decay by half.]

  • Cesium-134 ~ 2  years
  • Cesium-137 ~ 30 years
  • Iodine-131 ~ 8 days
  • Plutonium-239 ~ 24,200 years
  • Ruthenium-103 ~ 39 days [Ruthenium is a fission product of uranium-235.]
  • Ruthenium-106 ~ 374 days
  • Strontium-90 ~ 28.85 years  [Strontium-90 is a product of nuclear fission and is found in large amounts in spent nuclear fuel and in radioactive waste from nuclear reactors.]
  • Uranium-234 ~  246,000 years
  • Uranium-235 ~ 703.8  million years
  • Uranium-238  ~ 4.468 billion years

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Nebraska Nuke Plant Remains Shut After Missouri River Flooding

Posted by feww on June 20, 2011

The Fort Calhoun NPP in Nebraska still in shutdown following Missouri River flooding  

The federal government insists the plant has not flooded and is NOT expected to pose any danger.


Original caption: The Fort Calhoun nuclear power station in Fort Calhoun, Neb., currently shut down for refueling, is surrounded by flood waters from the Missouri River, Tuesday, June 14, 2011. On Tuesday, the releases at Gavins Point Dam in South Dakota hit the maximum planned amount of 150,000 cubic feet of water per second, which are expected to raise the Missouri River 5 to 7 feet above flood stage in most of Nebraska and Iowa. (AP Photo/Nati Harnik). Image may be subject to copyright.

The 480-megawatt plant which is located north of Omaha shut down about 10 weeks ago to refuel, but has remained shut since due to flooding, according to Omaha Public Power District (OPPD).

The Fort Calhoun NPP has a single CE pressurized water reactor generating about 480 megawatts of electricity, the smallest commercial power reactor in North America.

OPPD is “a customer-owned utility,” which provides electricity to about 346,000 customers in all or parts of 13 counties in east and southeast Nebraska.

“Floodwaters are already surrounding the Fort Calhoun plant. The river has risen 1.5 feet higher than Fort Calhoun’s 1,004-foot elevation above sea level, but the water is being held back by an 8-foot-tall flood barrier,” a report said on Friday.

“When the river reaches 1,004 feet above mean sea level, we shut down,” said OPPD spokesman Jeff Hanson. “We don’t have any idea when we’ll be able to start again.”

OPPD has not issued any updates since June 16, 2011.


Map of the flight restricted areas. Click image to enlarge.

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Chernobyl: Consequences of the Catastrophe for People and the Environment

Posted by feww on May 6, 2011

Chernobyl: Consequences of the Catastrophe for People and the Environment

The book is available online.  http://bit.ly/mo29TZ 

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Chernobyl nuclear disaster: 25th anniversary

Posted by feww on April 26, 2011

1 Million Killed in Chernobyl Disaster

Ukraine marks the 25th anniversary of Chernobyl nuclear disaster

On 26 April 1986 Reactor 4 at Chernobyl NPP in Ukraine, then in the Soviet Union, exploded releasing about one hundred times more radiation than the atom bombs dropped over Hiroshima and Nagasaki in 1945. 


Ukrainian city of Chernobyl had managed to live for 793 years… that is until the Chernobyl nuclear power plant underwent a core meltdown on April 26, 1986 at about 1:00am local time. This image was taken by authorities in the former Soviet Union

Remembering Chernobyl Victims


The sarcophagus covering the damaged fourth reactor at the Chernobyl nuclear power plant is seen behind a building decorated with a graffiti in the abandoned city of Prypiat April 4, 2011. Belarus, Ukraine and Russia will mark the 25th anniversary of the nuclear reactor explosion in Chernobyl, the place where the world’s worst civil nuclear accident took place, on April 26. Engineers are still struggling to regain control of damaged reactors at the Fuskushima plant after last month’s earthquake and tsunami, in the worst nuclear crisis since Chernobyl in 1986, with the government urging the operator of the plant to act faster to stop radiation spreading. REUTERS/Gleb Garanich. Image may be subject to copyright. Reuters images …


Birth defects and cancer were the norm for many years following the Chernobyl disaster.  By the time  residents of Pripyat, a town located near the plant, were ordered to evacuate, about two days after the Chernobyl core meltdown had occurred, many had already been exposed to varying doses of radiation poisoning.

The Incident: A meltdown of the reactor’s core in the Chernobyl power plant killed thirty people in 1986. About 135,000 people were evacuated. It is believed that about one hundred times more radiation was released in the accident than by the atom bombs dropped over Hiroshima and Nagasaki in 1945.

Legacy: More than 4,000 cases of thyroid cancer were diagnosed among children and adolescents between 1992 to 2002 in Belarus, Russia and Ukraine. Victims under 14 years were most severely affected by the elevated concentrations of radioiodine found in milk.

Incidents of skin lesions, respiratory ailments, infertility and birth defects were readily found among the more than five million people who inhabit the affected areas of Belarus, Russia, and Ukraine for many years following the accident.

The Poisoned land. Up to 5 million people continue to live on radioactive contaminated land. About 85% of the children who live in contaminated areas of Belarus today are ill, a near 6-fold increase compared to the time before the explosion (15%), according to The Belarusian National Academy of Sciences.

Disputed Facts: The above facts, however, have been disputed by a number of individuals including the author of a recent WHO report, and the retired “nukophile” British academic, James Lovelack. Local and international experts, however, have dismissed the WHO report findings. A UN report released in 2005 estimated the number of victims at just 4,000. Their figure is hotly disputed  by NGOs and independent experts.

“A report by Alexey Yablokov, Vassily Nesterenko and Alexey Nesterenko which appeared in the Annals of the New York Academy of Science showed that by 2004, there were 985,000 additional deaths worldwide caused by the nuclear disaster, including 212,000 of them within Western Russia, Belarus and Ukraine.”

Chernobyl fallout covers the entire Northern Hemisphere

Consequences of the Catastrophe. Authors  Alexey Yablokov (Center for Russian Environmental Policy in Moscow), Vassily Nesterenko and Alexey Nesterenko ( Institute of Radiation Safety, Minsk, Belarus) studies about 5,000 reports and scientific  papers mostly published in Slavic languages and compiled their finding in the  book “Chernobyl: Consequences of the Catastrophe for People and the Environment,” which was published last year on the 24th anniversary of the Chernobyl reactor core meltdown.

“For the past 23 years, it has been clear that there is a danger greater than nuclear weapons concealed within nuclear power. Emissions from this one reactor exceeded a hundred-fold the radioactive contamination of the bombs dropped on Hiroshima and Nagasaki.” They wrote.

“No citizen of any country can be assured that he or she can be protected from radioactive contamination. One nuclear reactor can pollute half the globe,” the authors said. “Chernobyl fallout covers the entire Northern Hemisphere.”

According to the book, a total of about 830,000 people, referred to as the “liquidators,” were responsible for various emergency works at the Chernobyl site including fire extinguishing, decontamination and cleanup.

The authors say between 112,000 and 125,000 of the  liquidators had died by 2005.  The authors also estimate that between 1986 and 2004 some 985,000 people died as a result of Chernobyl fallout {2011 estimates are well over a million deaths.]

“Official discussions from the International Atomic Energy Agency and associated United Nations’ agencies (e.g. the Chernobyl Forum reports) have largely downplayed or ignored many of the findings reported in the Eastern European scientific literature and consequently have erred by not including these assessments.” The authors said last year.

Chernobyl and Other Nuclear Stats

  • More than 95% of the radioactive material (180 metric tons with a radioactivity of about 18 million curies) still remains inside the Chernobyl reactor.
  • The  core meltdown at Chernobyl was said to have released radiation estimated at 50 million curies. Committee on the Safety of Nuclear Installations said in 1995 that the meltdown had released about 140 million curies. [Researchers Alexey Yablokov, Vassily Nesterenko and Alexey Nesterenko say the radiation released from Chernobyl may have been up to 10 billion curies. In comparison, the Hiroshima bomb released about 3 million curies.]
  • Immediately after the accident, 237 people suffered from acute radiation sickness, and 31 died within the first 90 days of the disaster.
  • About 135,000 people were evacuated from the area surrounding the plant, including 50,000 from the town of Pripyat.
  • The Academy’s  estimate for the number of casualties  are more than 90,000 deaths and more than a quarter of a million cancer cases.
  • The Ukrainian National Commission for Radiation Protection calculates the number of radiation casualties at half a million  deaths so far.
  • In a book published by the New York Academy of Sciences last year on the 24th anniversary of the reactor core meltdown, the researchers maintain that about one million people have died from exposure to radiation released by the Chernobyl reactor so far [as of 2010.]
  • “In the former Soviet Union at least 9 million people have been effected by the accident; 2.5 million in Belarus; 3.5 million in Ukraine; and 3 million in Russia. In total over 160 000 Km2 are contaminated in the three republics.” source
  • Some 441 commercial nuclear power reactors are  operating in 31 countries ( total capacity of 376 gigawatts) each of which is potentially as lethal as Chernobyl, if not worse. [This item, updated here, was written before the Fukushima nuclear disaster began unfolding.]
  • An estimated 56 countries operate more than 250 research reactors.
  • At least 220 nuclear reactors power military ships and submarines.

Fukushima NPP

Fukushima NPP is said to contain about 4,277 tons of nuclear fuel, about 24 times as much as Chernobyl (~ 180 tons).

“The Fukushima Dai-ichi site has a considerable number of fuel rods on hand, according to information provided Thursday by Toyko Electric Power Co., which owns the atomic complex: There are 3,400 tons of fuel in seven spent fuel pools within the six-reactor plant, including one joint pool storing very old fuel from units 3 and 4. There are 877 tons in five of the reactor cores. Officials have said that the fuel in Unit 4′s reactor vessel was transferred to its spent fuel pool when the unit was temporarily shut in November.” AP reported.

On April 12, Japanese authorities raised the measure of severity of the Fukushima NPP disaster to the maximum level of 7 on INES. (See below for details.)

The International Nuclear and Radiological Event Scale (INES)

The INES, a logarithmic scale, which was introduced in 1990 by the IAEA to enable prompt communication, classifies the intensity of nuclear incidents as follows:

7 – Major Accident [Chernobyl disaster, criticality accident, April 1986]

6 – Serious Accident [e.g., Kyshtym incident, Mayak, former Soviet Union, steam explosion released up to 80 tons of highly radioactive material into the atmosphere, September 1957. ]

5 – Accident With Wider Consequences [e.g., Three Mile Island accident  Pen State, U.S., partial meltdown release radioactive gases  into the environment, March 1979.]

4 – Accident With Local Consequences [e.g., Sellafield, UK, at least 5 incidents reported between 1955 to 1979]

3 – Serious Incident [e.g., Vandellos NPP, Spain, fire destroyed control systems; the reactor was shut down, July1989]

2 – Incident [e.g., Forsmark NPP, Sweden, a backup generator failed, July 2006]

1 – Anomaly [e.g., TNPC, France, 1,600 gallons of water containing 75 kilograms (170 lb) of uranium leaked into the environment,  July 2008]

0 – Deviation (No Safety Significance) — [e.g., Atucha, Argentina – Reactor shutdown caused by tritium increase in reactor encasement, December 2006.]

What is a lethal dose of radiation from a single Exposure?

Studies of the 1945 atomic bombing at Hiroshima and Nagasaki show that 100 percent of victims whose bodies were exposed to 600,000 millirems (6,000 mSv) died from radiation. About 50 percent of victims who received  450,000 millirems (4,500 mSv) of radiation also died.

(Note: Rem is a unit of ionizing radiation equal to the amount that produces the same damage to humans as one roentgen of high-voltage x-rays.  Source: MIT)

1 rem = 10 mSv  (1 Sv = 100 rem)

Background Radiation in millirems per year (mrem/yr)

  • Average background radiation (US):  300
  • Higher altitudes (e.g, Denver): 400

“Safe Levels” of Radiation (U.S.)

Limits above natural background radiation levels (average 300 millirems per year) and medical radiation:

  • Occupation Limit: Maximum of 5,000  (the limit for a worker using radiation)
  • Average Natural Background: 300

[Note: Lifetime cumulative exposure should be limited to a person’s age multiplied by 1,000 millirems, e.g., a 70-year-old person, 70,000 millirems.]

Adults

  • Max single dose for an adult: 3,000
  • Annual total dose: 5,000

Under 18

  • Max single dose for a person aged under 18 years: 300 millirems (whole body equivalent)
  • Annual total exposure: 500

Fetal Exposure

  • Maximum limit for fetal exposure during gestation period:  50 millirems per month above background levels

Medical

  • Single Chest X-ray (the whole body equivalent): 2 millirem

Air Travel

  • Coast-to-coast US round trip flight: 12 millirems

*Note:  Radiation dose of about 2,000 millisieverts (200,000 millirems) cause serious illness.

Half-life of some radioactive elements

[NOTE: Half-life is the time taken for a radioactive substance to decay by half.]

  • Cesium-134 ~ 2  years
  • Cesium-137 ~ 30 years
  • Iodine-131 ~ 8 days
  • Plutonium-239 ~ 24,200 years
  • Ruthenium-103 ~ 39 days [Ruthenium is a fission product of uranium-235.]
  • Ruthenium-106 ~ 374 days
  • Strontium-90 ~ 28.85 years  [Strontium-90 is a product of nuclear fission and is found in large amounts in spent nuclear fuel and in radioactive waste from nuclear reactors.]
  • Uranium-234 ~  246,000 years
  • Uranium-235 ~ 703.8  million years
  • Uranium-238  ~ 4.468 billion years

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