World Health Organization - Fact sheet N° 303 - April 2006

Background

On 26 April 1986, explosions at reactor number four of the nuclear power plant at Chernobyl in Ukraine, a Republic of the former Soviet Union at that time, led to huge releases of radioactive materials into the atmosphere. These materials were deposited mainly over countries in Europe, but especially over large areas of Belarus, the Russian Federation and Ukraine.

An estimated 350 000 clean-up workers or "liquidators" from the army, power plant staff, local police and fire services were initially involved in containing and cleaning up the radioactive debris during 1986-1987. About 240 000 liquidators received the highest radiation doses while conducting major mitigation activities within the 30 km zone around the reactor. Later, the number of registered liquidators rose to 600 000, although only a small fraction of these were exposed to high levels of radiation.

In the spring and summer of 1986, 116 000 people were evacuated from the area surrounding the Chernobyl reactor to non-contaminated areas. Another 230 000 people were relocated in subsequent years.

By YURI KAGEYAMA and JUSTIN PRITCHARD, Associated Press 

TOKYO – Japanese nuclear regulators trusted that the reactors at the Fukushima Dai-ichi complex were safe from the worst waves an earthquake could muster based on a single-page memo from the plant operator nearly a decade ago. In the Dec. 19, 2001, document — one double-sized page obtained by The Associated Press under Japan's public records law — Tokyo Electric Power Co. rules out the possibility of a tsunami large enough to knock the plant offline and gives scant details to justify this conclusion, which proved to be wildly optimistic.

May 17, 2011

The International Atomic Energy Agency will dispatch an international expert fact-finding mission to Japan.

Based upon the agreement between the IAEA and the Government of Japan, the mission, comprising nearly 20 international and IAEA experts from a dozen countries, will visit Japan between 24 May and 2 June 2011. Under the leadership of Mr. Mike Weightman, HM Chief Inspector of Nuclear Installations of the United Kingdom, the mission will conduct fact-finding activities at Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Station (NPS) site and in other locations.

The expert mission will make a preliminary assessment of the safety issues linked with TEPCO's Fukushima Dai-ichi NPS accident following the Great East Japan Earthquake and Tsunami. During the mission, areas that need further exploration or assessment based on the IAEA safety standards will also be identified.

In the course of the IAEA mission, the international experts will become acquainted with the Japanese lessons learned from the accident and will share their experience and expertise in their fields of competence with the Japanese authorities.

Time - May 24, 2011

Two weeks after announcing the meltdown of fuel inside Fukushima's No. 1 reactor, Tokyo Electric Power Company (TEPCO) has said there have very likely been partial meltdowns at the other two reactors that were operating when the crisis began on March 11 as well. A spokesman for TEPCO, Japan's largest power company that has come under fire for its management of the crippled plant, said fuel rods at reactor No. 3 started melting March 13, two days after the 9.0 earthquake and ensuing tsunami struck the plant. Fuel rods at No. 2 probably started melting a day later, on March 14.

JapanToday.com - May 24, 2011

TOKYO —

The operator of the troubled Fukushima Daiichi nuclear power complex said Tuesday that meltdowns are assumed to have occurred in the cores of the Nos. 2 and 3 reactors in addition to the meltdown already confirmed at the No. 1 reactor, but stressed that it believes the melted fuel is being kept cool at the bottom of the pressure vessels.

Tokyo Electric Power Co also maintained its view that it was only after the giant tsunami hit after the devastating March 11 earthquake that the plant lost all its power sources, eventually leading to the loss of the reactors’ key cooling functions.

The announcement came as the utility is proceeding with work to assess data taken shortly after the nuclear accident occurred. Industry minister Banri Kaieda said the government agreed at a cabinet meeting Tuesday to set up a third-party panel to look into the causes of the country’s worst ever nuclear crisis.

The government has tapped Yotaro Hatamura, a 70-year-old professor emeritus at the University of Tokyo, as head of the special panel, Deputy Chief Cabinet Secretary Yoshito Sengoku said in a press conference.

Huffington Post - AOL News - May 19, 2011

The Tokyo Electric Power Company (TEPCO) has released a dramatic series of photos that show the March 11 tsunami battering the now-crippled Fukushima Daiichi nuclear plant.

The photos, which first appeared on TEPCO's website Thursday, saw a colossal surge of water breaching the seawall guarding the plant as well as the flood inundating some of the plant's buildings, leaving several cars bobbing in the water, Voice of America is reporting.

The tsunami was triggered by a magnitude 9.0 earthquake which struck off Japan's northeast coast.

View dramatic photos of the tsunami, courtesy of TEPCO, in the link below:

Experts have warned of a potentially dangerous radiation leak if Japanproceeds with plans to flood a damaged reactor containment vessel at the Fukushima Daiichi nuclear plant. The facility's operator has admitted uranium fuel rods in the No 1 reactor partially melted after being fully exposed because of the 11 March tsunami.

Chubu Electric asked to 'swiftly consider' government's request

CBC News - Posted: May 6, 2011 7:38 AM ET

Japan has urged a power company to suspend all three reactors at a coastal nuclear plant while a seawall and other structures are built to ensure a major earthquake or tsunami does not cause a second radiation crisis.

The move came Friday as the government is conducting a safety review of all Japan's 54 nuclear reactors after the Fukushima Daiichi nuclear plant was crippled by the March 11 earthquake and tsunami that left more than 25,000 people dead and missing on the northeast coast.

The Hamaoka nuclear plant just 100 metres off the Pacific coast in central Japan is the only one so far where the government has asked that operations be halted until the utility can implement safety measures.

Chubu Electric Power Co. said in a statement it will "swiftly consider" the government's request. The statement gave no further details. Government officials estimate the work could last two years.

Prime Minister Naoto Kan said at a news conference Friday evening he requested the shutdown for safety reasons, citing experts' forecast of a 90 per cent probability of a quake with magnitude of 8.0 or higher striking central Japan within 30 years.

AP - by Elaine Kurtenbach and Mari Yamaguchi - April 20, 2011

TOKYO -- Japanese authorities may for the first time strictly enforce their evacuation zone around a crippled nuclear plant, citing concerns Wednesday over radiation risks for residents returning to check on their homes.

About 70,000-80,000 people were living in the 10 towns and villages within 12 miles (20 kilometers) of the Fukushima Dai-ichi plant before the March 11 earthquake and tsunami wrecked its power and cooling systems, setting off the worst nuclear power crisis since the 1986 catastrophe at Chernobyl.

Virtually all of the residents left when the government ordered the area evacuated on March 12, but some occasionally have returned and police cannot legally block them. There currently is no penalty for violating the zone.

"We are considering setting up 'caution areas' as an option for effectively limiting entry" to the zone, Chief Cabinet Secretary Yukio Edano said.

Prime Minister Naoto Kan will meet with local officials and evacuees to discuss the plans during a visit to the affected region Thursday, Edano said.

AP - AOL News - by Mari Yamaguchi - April 18, 2011

TOKYO -- Readings Monday from robots that entered two crippled buildings at Japan's tsunami-flooded nuclear plant for the first time in more than a month displayed a harsh environment still too radioactive for workers to enter.

Nuclear officials said the radiation data for Unit 1 and Unit 3 at the tsunami-flooded Fukushima Dai-ichi plant - collected by U.S.-made robots that look like drafting lamps on treads - do not alter plans for stabilizing the complex by year's end under a "road map" released by the plant operator Sunday.

With the public growing increasingly frustrated at the slow response to the earthquake, tsunami and nuclear crises, parliament grilled Prime Minister Naoto Kan and officials from plant operator Tokyo Electric Power Co.

"You should be bowing your head in apology. You clearly have no leadership at all," Masashi Waki, a lawmaker from the opposition Liberal Democratic Party, shouted at Kan.

"I am sincerely apologizing for what has happened," Kan said, stressing that the government was doing all it could to handle the unprecedented disasters.

TEPCO's president, Masataka Shimizu, looked visibly ill at ease as lawmakers heckled and taunted him.