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Nuclear Accidents: Fukushima

On 11 March 2011 a strong earthquake and, following this, a tsunami occurred in Fukushima/Japan. Significant damage was done to the Fukushima Daiichi nuclear power plant, which was impossible to manage with the available safety and security systems. The radioactive substances released as a result of this accident have contaminated air, soil and water in the area around Fukushima. So far, it has not been possible to evaluate health effects finally.

Aerial view of the Fukushima Daiichi nuclear power plant in JapanSource: Taro Hama @ e-kamakura/Moment/Getty Images

The Fukushima accident

On 11 March 2011, a strong earthquake and subsequent tsunami hit Fukushima in Japan. The Fukushima Daiichi nuclear power plant suffered major damage that could not be managed with the existing safety systems. The radioactive substances released in the accident contaminated air, soil and water in the region around Fukushima. Approximately 120,000 people were evacuated as a preventive measure or because of the high radiation.

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Japanese visitor in whole body counter in Berlin

Health consequences

The radioactive substances (radionuclides) released into the atmosphere as a result of the reactor accident in Fukushima on 11.03.2011 were dispersed locally, regionally and globally by the wind and subsequently deposited onto the Earth's surface. Internal radiation exposure to humans occurred through radioactive substances inhaled from the air and further on through ingestion with food. External exposure occurred through radioactive substances in the air and through radionuclides deposited on the ground.

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Report of BfS as of 8 March 2012: "Die Katastrophe im Kernkraftwerk Fukushima nach dem Seebeben vom 11. März 2011: Beschreibung und Bewertung von Ablauf und Ursachen"

BfS report on the accident's development and causes

One year after the nuclear disaster at Fukushima, the Federal Office for Radiation Protection (BfS) published a report on the development of the accident and its causes. The basic details of the accident and how it progressed are well known. In terms of what happened within the reactors themselves, however, at the time of reporting the experts were dependent on observations which can be made from outside, the knowledge that comes from experience, and reconstruction models using data acquired by other means.

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Tablets

Use and effectiveness of iodine tablets

Radioactive iodine may be released in a nuclear accident. To prevent this from accumulating in the thyroid, non-radioactive iodine should be taken in the form of high-dose tablets at the appropriate time (this is known as iodine thyroid blocking). Iodine tablets (also referred to as potassium iodide tablets) for iodine thyroid blocking should be taken only after explicit request by the responsible authorities.

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Map of Japan with Deposition of caesium-137 in kBq/m2 following the Fukushima reactor accident: Measurement results of the surveys carried out by MEXT for airborne monitoringSource: UNSCEAR 2013 Report, Volume I, ANNEX A, Figure B-VIII / reproduced by permission of UNSCEAR

Environmental impact of the Fukushima accident

The reactor accident in Fukushima resulted in the release of radioactive material into the atmosphere. This material was then dispersed over land and sea by wind and precipitation. To this day, radioactive material continues to enter the water that is used to cool the Fukushima reactors. Most foodstuffs in Japan are no longer radioactively contaminated, with one exception being highly contaminated wild boar.

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All radionuclide measurement stations of CTBTO are recorded on the world mapSource: © CTBTO (https://www.ctbto.org/our-work/ims-map)

Trace analysis worldwide: Results associated with the accident in Fukushima

The CTBTO has a worldwide monitoring network. Once completed it consists of 80 radionuclide measurement stations for detection of radionuclides bound to airborne dust. In addition, 40 of these stations are equipped with systems for the measurement of radioactive xenon. One of these radionuclide monitoring stations is operated by the Federal Office for Radiation Protection (BfS) on Mt Schauinsland near Freiburg im Breisgau. After the accident at the nuclear power plant in Fukushima, Japan, in 2011, the station was able to detect radioactivity from Fukushima at trace levels.

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Illustration of a magnifying glass with a column chart

Fallout compared

Above-ground nuclear weapon tests and reactor accidents result in the release of radioactive substances into the atmosphere. This radioactive material can then be deposited on the Earth's surface (as "fallout") by precipitation, for example. In Europe, the only appreciable radioactive exposure has been as a result of the above-ground nuclear weapon tests in the 1950s and 1960s and the Chornobyl (Russian: Chernobyl) reactor accident. In contrast, the reactor accident in Fukushima (Japan) did not result in appreciable radioactive exposure in Europe.

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