JAPON YA HA TENIDO TRAGEDIAS NUCLEARES POR REACTORES ATÓMICOS: the worst nuclear accident of Japan: Tokaimura,1999

malcolmallison I malcolmallison

Publicado: 2011-03-17

En la localidad Tokaimura (prefectura de Ibaraki, Japón), a unos 140 km de Tokio se produjeron dos accidentes nucleares de considerable importancia. Uno en 1997 y el otro dos años más tarde, en 1999.

Accidente de Tokaimura de 1999

El accidente que se produjo el 30 de septiembre de 1999 en una planta de reciclaje de combustible nuclear de la empresa JCO fue todavía más grave que uno precedente en el mismo lugar, dos años antes. A las 12.00 saltaron las alarmas de la planta y en un primer momento se desalojaron las casas más cercanas y se estableció un perímetro de seguridad de 350 m. A las 23.00 viendo la magnitud del problema las autoridades decidieron establecer un perímetro de 10 km y recomendar a las 310.000 personas que vivían dentro de él que no saliesen de sus casas.

La empresa reconoció que la causa había sido una sobrecarga de uranio: habían aplicado 16 kg del elemento químico cuando el máximo era 2,3. Pero este error no hubiera podido cometerse si se hubiera aplicado la medida de prevención de riesgos laborales obligatoria de no usar recipientes que pudiesen contener una medida mayor a la masa crítica.

Se llegaron a alcanzar niveles de hasta 15.000 veces el límite de lo permisible para la vida. Otros informes señalaron que esa cifra alcanzó las 40.000.

Se prohibió pescar y beber en las aguas cercanas al accidente.

Se prohibió la cosecha de cualquier explotación agrícola.

49 personas entre población y trabajadores sufrieron daños de diversa gravedad y dos de ellas murieron a causa de la exposición a la radioactividad.

Como resultado seis altos cargos de la empresa JCO fueron condenados a penas de entre dos y tres años de cárcel por negligencia.

Accidente de 1997

A las 10.00 del 11 de marzo de 1997 en la planta de procesamiento de desperdicios de baja radiactividad de la corporación Donen (Corporación de Desarrollo Nuclear) se declaró un incendio haciendo sonar las alarmas. La reacción de los operarios llegó a los cuatro minutos cuando arrojaron un metro cúbico de agua sobre el fuego, extinguiéndolo.

Aunque parecía que el peligro había pasado y la situación estaba controlada a las 18.04 de ese día hubo una explosión en esa misma planta que destrozó algunos muros y ventanas del edificio.

Como consecuencia 37 trabajadores de los 112 que estaban en ese momento trabajando en la planta fueron expuestos a niveles de radiación ligeramente superiores a los normales (60 millones de becquerel) aunque sin llegar a ser peligrosos.

the worst nuclear accident of Japan: Tokaimura, September 30, 1999

Friday, October 1, 1999 Published at 17:12 GMT 18:12 UK

World: Asia-Pacific

In pictures: Japan's worst nuclear accident

http://cdnedge.bbc.co.uk/1/hi/world/asia-pacific/462003.stm

Police in Japan are questioning officials from the company which runs the uranium fuel processing plant at the centre of the country's worst nuclear accident. The authorities say Tokaimura, where the plant is situated, is now safe and radiation levels have returned to normal.

"A major accident resulting in a radioactive leak has happened. We apologise from the bottom of our hearts," said company President Koji Kitani, bowing deeply at a news conference in Tokyo on Thursday.

On Friday morning, JCO President Kitani, foreground, knelt down on the ground to apologise in front of the residents who took shelter in a community centre at Tokai

Three workers saw a blue flash and were overcome with nausea. They were taken to hospital barely conscious and with low blood pressure. Several other colleagues are also suffering from radiation exposure

Workers were taken a hospital at the National Institute of Radiological Sciences in Chiba.

Those closest to the plant were evacuated and given radiation checks

Children are particularly vulnerable to radiation. They were given thorough checks

On Friday, residents were told it was safe to go outdoors again - most chose to stay inside their houses though. The police remained cautious, too, and continued to don protective gear.

Protesters staged a demonstration at the Science and Technology Agency in Tokyo. The banner reads: "Denounce Tokaimura nuclear processing facilities and development of Japan's nuclear power plants."

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11 Nuclear Meltdowns and Disasters

On March 11, 2011, an earthquake measuring 9.0 on the Richter scale struck Japan, bringing a destructive tsunami along with it. One of the sites most affected by the devastation was the Fukushima Daiichi nuclear power plant, which experienced a partial meltdown two days after the quake.

The incident is being called the worst nuclear accident since the 1986 disaster at Chernobyl, www.cnbc.com/id/42112536

Chernobyl, Ukraine (1986)

On April 26, 1986, a reactor at the Chernobyl power plant in Ukraine exploded, causing the worst nuclear accident the world has seen. It sent a plume into the atmosphere with radioactive fallout that was 400 times greater than that released in the atomic bombing of Hiroshima. The plume drifted across much of the western Soviet Union. Parts of Eastern, Northern and Western Europe were also affected.

Tokaimura, Japan (1999)

Until March 2011, the worst nuclear accident in the history of Japan took place at a uranium facility in Tokaimura on September 30, 1999. Three workers were attempting to mix nitric acid and uranium to form the fuel uranyl nitrate. However, the workers unknowingly used seven times the allowable limit of uranium, and the reactor couldn’t stop the solution from reaching critical mass.

http://media.cnbc.com/i/CNBC/Sections/News_And_Analysis/_News/_SLIDESHOWS/NuclearDisasters/CNBC_11_nuclear_meltdowns_disasters_tokaimura.jpg

Three Mile Island, Pennsylvania (1979)

The worst nuclear accident in U.S. history took place on March 28, 1979 at the Three Mile Island plant in Pennsylvania. A cooling system failed, causing a partial meltdown, but a full meltdown was averted and there were no fatalities. However, despite the positive outcome and despite the passage of more than 30 years, the incident remains fresh in the minds of those who are old enough to remember it.

Goiania, Brazil (1987)

One of the worst nuclear contamination incidents in the world took place in Goiania, Brazil. A radiotherapy institute in the city had relocated, leaving behind a teletherapy unit that still contained cesium chloride.

On September 13, 1987, two scavengers found the unit, carted it away in a wheelbarrow and sold it to a junkyard. The owner invited friends and family to see the glowing blue material

K-19, North Atlantic Ocean (1961)

On July 4, 1961, the Soviet submarine K-19 was in the North Atlantic Ocean when it developed a radioactive leak. It had no coolant system in place to stop the reactor from overheating and exploding, so with no other options, the crew entered the reactor compartment and fixed the leak, exposing themselves to levels of radiation in the process that were certain to kill them. All eight crew members who had fixed the leak died of

Kyshtym, Russia (1957)

In the years following World War II, the United States was the foremost nuclear power in the world. In an effort to catch up, the Soviet Union quickly built nuclear power plants and cut corners in order to keep pace.

The Mayak plant near the city of Kyshtym had a tank with a substandard cooling system as a result, and when it failed, the increasing temperature caused an explosion that

Windscale, England (1957)

On October 10, 1957, Windscale became the site of the worst nuclear accident in British history, and the worst in the world until Three Mile Island 22 years later. A facility had been built there to produce plutonium, but when the US successfully designed a nuclear bomb that used tritium, the facility was used to produce it for the UK. However, this required running the reactor at a higher temperature than its design could sustain, and it eventually caught fire.

SL-1, Idaho (1961)

The Stationary Low-Power Reactor Number One, or SL-1, was a nuclear reactor located in the desert forty miles outside of Idaho Falls, Idaho. On January 3, 1961, the reactor exploded, killing three workers and causing a meltdown. The cause was a control rod that had been withdrawn incorrectly, but even after an investigation that took two years to complete, the actions taken by the workers just prior to the accident were never

North Star Bay, Greenland (1968)

On January 21, 1968, a US Air Force B-52 bomber was running a “Chrome Dome” mission, a Cold War-era operation in which US bombers with nuclear payloads stayed in the air at all times, all with nearby targets in the Soviet Union that were to be attacked if commanded. The bomber, which was carrying four hydrogen bombs caught fire. The nearest emergency landing location was at Thule Air Base in Greenland, but there was not enough

Jaslovské Bohunice, Czechoslovakia (1977)

The Bohunice nuclear power plant was the first to be built in Czechoslovakia. The reactor was based on an experimental design that was meant to run on uranium mined in Czechoslovakia. However, the first-of-its-kind facility had multiple accidents, and it had to be shut down more than 30 times.

Two workers had been killed in a 1976 incident, but the worst mishap occurred on

Yucca Flat, Nevada (1970)

Located one hour from Las Vegas, Yucca Flat is a desert basin that has served as one of Nevada’s nuclear test sites. On December 18, 1970, while detonating a 10 kiloton nuclear bomb buried 900 feet underground, the plug sealing the explosion from the surface cracked, sending a plume of radioactive fallout into the air and contaminating 86 workers who were on the site.

the worst nuclear accident of Japan: Tokaimura, September 30, 1999

The International Nuclear Event Scale

For prompt communication of safety significance

http://www.world-nuclear.org/info/inf37.html

Level, Descriptor

Off-Site Impact

On-Site Impact

Defence-in-Depth Degradation

Examples

Major Accident

Major Release:

Widespread health and environmental effects

Chernobyl, Ukraine, 1986

Serious Accident

Significant Release: Full implementation of local emergency plans

Accident with Off-Site Risks

Limited Release:

Partial implementation of local emergency plans

Severe core damage

Windscale, UK, 1957 (military).

Three Mile Island, USA, 1979.

Accident Mainly in Installation

either of:

Minor Release:

Public exposure of the order of prescribed limits

Partial core damage. Acute health effects to workers

Saint-Laurent, France, 1980 (fuel rupture in reactor).

Tokai-mura, Japan, Sept 1999.

Serious Incident

any of:

Very Small Release:

Public exposure at a fraction of prescribed limits

Major contamination, Overexposure of workers

Near Accident. Loss of Defence-in-Depth provisions

Vandellos, Spain, 1989 (turbine fire, no radioactive contamination)

Incident

nil

Incidents with potential safety consequences

Anomaly

nil

Deviations from authorised functional domains

Below Scale

nil

No safety significance

Source: International Atomic Energy Agency

For prompt communication of safety significance