Situation at Fukushima NPP – latest developments

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  • 2013-09-20

The National Atomic Energy Agency provides update on the situation at disabled Fukushima Daiichi nuclear power plant on the basis of the latest materials obtained.   

In the last three months, at the site of Fukushima nuclear power plant, the contaminated water from storage tanks, which was used to cool reactors, has been leaking into the ground. According to the latest news and measurements, the contamination is only limited to the emergency zone that is to the sealed off site of the plant.   

There has been no detection of a significant increase in the concentration of radioactive substance in the seawater off the coast of Japan, even in the close vicinity of the nuclear power plant. In a few sampling points, the activity of the mentioned  elements exceeded the lower limit of detection, however the results oscillated around the detectable limit. The results published concerning sea area monitoring show that artificial radioactive elements in the seawater near Fukushima have been gradually decreasing over a period of time.

 According to the statement by Japan’s Prime Minister, the radiation situation is under control. The Government of Japan declares that it will closely follow the development of situation and that it will put its best efforts to prevent the leakage of contaminated water. It also made commitment to inform the international community about the current developments.     

Additional expert’s clarification 

 Impact of contaminated water on the environment

The contamination of seawater with radioactive cesium-134 and cesium-137 isotopes occurs only in the closed area of the seaport at the nuclear power plant (the area of around 0.3 km2). 

The radioactivity of elements in seawater was measured in six sea areas, established near the nuclear power plant.  First three areas were established respectively within: 2 km radius, 2-20 km radius and 20-60 km radius from the nuclear power plant.

Radioactive concentration for the following isotopes was identified:  Cs-134 caesium, Cs-137 caesium, H-3 tritium, Sr-90 strontium, Pu-238 plutonium, Pu-239 plutonium, Pu-240 plutonium, and the concentration of total α activity and concentration of total β activity.

In the first area, the measurements were taken in five sampling points. In four points, concentration values were below the limit of detection. In one point the concentration for  Cs-137 caesium was at the level of 1.7 Bq/l (as of 6 August). Six days later the concentration dropped to the level of 1.4 Bq/l. The concentration for tritium amounted then to 4.7 Bq/l, and about two weeks later it was below the limit of detection.

Map of the coast off Fukushima Daiichi nuclear power plant showing results of sea area monitoring for radioactive element concentration . Photo. Nuclear Regulation Authority, Japan

In the second sea area, the measurements were taken in 16 sampling points, each at the depth of 2 meters under the sea level and 2-3 meters from the seabed. In most sampling points, very sensitive monitoring was able to show the minimum concentration of Cs-134 and Cs-137 amounting to the fraction of hundredth or thousandth of Bq/l. Similar results were obtained from monitoring conducted in the area number three, four, five and six.

The provisions of the European Union and International Atomic Energy Agency do not specify the value of permissible concentration for radioactive elements in the seawater. It must be pointed out that the strictest norms for permissible concentrations for drinking water specify the limit of 100 Bq/l (Council Directive of 3 November 1998 on the quality of water intended for human consumption and Drinking Water Quality Standards issued by the World Health Organization).

 Condition of damaged nuclear power plant

In all three power units, burnt and damaged fuel elements (which had been partially melted in the period following the accident) are still being cooled with water circulating in the close circuit.

Water treatment stations, which were developed on the site of the nuclear power plant, eliminate the radioactive substance contamination so that the water could be used again for cooling.

Safety of water and foodstuffs

Monitoring of foodstuffs which has been carried out for over 400,000 articles since 1 April 2012 shows that the limit has been exceeded for approximately 0.7% of foodstuffs samplings.

An annual radiation dose caused by the consumption of foodstuffs and water in Fukushima prefecture was below one hundredth of 1 mSv (limit dose for the population is 1mSv/per annum).

Preventive and rescue measures

The Government of Japan supports organizationally and financially the actions of TEPCO Company in limiting the spread of contamination beyond the site of nuclear power plant.

It was decided, among other things, to use the innovative technology to surround the stricken area with a massive underground wall of frozen soil, thereby preventing radioactive groundwater from leaking into the sea from the land situated higher above sea level and from the basement of the nuclear power plant. The initial cost estimate is 320 million dollars.

According to present plans regarding entire decommissioning activities of nuclear power plant (elimination of damaged fuel and dismantling of buildings), this process should take 30-40 years. 

The action for remedying damage is being performed with the participation of many scientific centres from around the world which are gathered the International Research Institute for Nuclear Decommissioning – IRID. The Institute started its activities in August 2013.

This release was prepared by the Public Communication Team of the PAA on the basis of:

  • Information provided by the representatives of the Government of Japan during the 57-th General Conference of the International Atomic Energy Agency from 16.09 to 20.09.2013 in Vienna;
  • Information published on 17.09.2013 in the USIE system by Nuclear Regulation Authority, Japan.