Fukushima Nuclear Accident Update Log
Updates of 28 March 2011
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- In Focus: Fukushima Nuclear Accident
- Fukushima Nuclear Accident: Information Sheet
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Fukushima Nuclear Accident Update (28 March 2011, 23:00 UTC)
Japan Confirms Plutonium in Soil Samples at Fukushima Daiichi
After taking soil samples at the Fukushima Daiichi nuclear power plant, Japanese authorities today confirmed finding traces of plutonium that most likely resulted from the nuclear accident there. The Nuclear and Industrial Safety Agency told the IAEA that the Tokyo Electric Power Company (TEPCO) had found concentrations of plutonium in two of five soil samples.
Traces of plutonium are not uncommon in soil because they were deposited worldwide during the atmospheric nuclear testing era. However, the isotopic composition of the plutonium found at Fukushima Daiichi suggests the material came from the reactor site, according to TEPCO officials. Still, the quantity of plutonium found does not exceed background levels tracked by Japan's Ministry of Education, Culture, Sports, Science and Technology over the past 30 years.
Ladies and Gentlemen,
I will make a few general introductory remarks before handing over to my colleagues for the Technical Briefing. The current situation can be summarised as follows:
- The situation remains very serious.
- Priority now is to overcome the crisis.
- We are also planning ahead.
- The IAEA is doing everything in its power to help Japan.
Let me elaborate a little.
The crisis at the Fukushima Daiichi plant has still not been overcome and it will take some time to stabilise the reactors.
For now, radioactivity in the environment, foodstuffs and water - including the sea - is a matter of concern in the vicinity of the Fukushima plant and beyond. Current levels indicate a need for further comprehensive monitoring.
On the positive side, electrical power has been restored at Units 1, 2 and 3 and fresh water is now available on the site.
Since I addressed the special Board meeting a week ago, we have put two radiation monitoring teams on the ground in Japan.
An FAO/IAEA Food Safety Assessment Team is also now on the spot, meeting officials in prefectures affected by contamination.
In a crisis of this nature, it is vital to provide, and share, speedy and accurate information.
From the beginning, we have been working closely with the Japanese government and with the safety agency NISA.
My visit to Tokyo, and the presence of IAEA staff on the ground, have improved both the flow of information and the level of mutual understanding of a variety of technical issues.
This has been an interactive process: as well as receiving information, we have been asking questions, providing advice and obtaining clarifications.
On Friday (25 March 2011), I took part in a video conference with UN Secretary-General Ban Ki-Moon and the heads of a number of major Agencies.
I explained that we have been working fully in accordance with the Joint Radiation Emergency Management Plan of the International Organizations. The Plan is co-sponsored by fifteen organisations and the IAEA is the focal coordinating body.
Our Incident and Emergency Centre has distributed information, channelled offers of cooperation, sent missions to Japan, and coordinated with partners including WHO, FAO, WMO, ICAO and CTBTO.
I will meet the UN Secretary General and the heads of agencies again later this week at the Chief Executives' Board meeting in Kenya to strengthen coordination.
Ladies and Gentlemen,
The crisis is not yet over, but we need to start thinking about the future.
Once the situation has been stabilised, the Agency would like to send an international expert mission to conduct an assessment of the accident. This should include an element of peer review.
The Fukushima crisis has confronted the Agency and the international community with a major challenge.
It is vitally important that we learn the right lessons from what happened on 11 March, and afterwards, in order to strengthen nuclear safety throughout the world.
Following my statement at the Board of Governors meeting last week (21 March 2011), many countries joined my call for robust follow-up action.
I would therefore like to propose that a high-level IAEA Conference on Nuclear Safety should take place here in Vienna before the summer.
The Conference should cover the following points:
- An initial assessment of the Fukushima accident, its impact and consequences;
- Considering the lessons that need to be learned;
- Launching the process of strengthening nuclear safety; and
- Strengthening the response to nuclear accidents and emergencies.
The work ahead will be substantial. I firmly believe that the IAEA is the best venue for follow-up on the Fukushima accident. We have the necessary expertise, extensive membership and can ensure transparency.
I will keep you informed and count on your full support and cooperation.
→ IAEA Briefing on Fukushima Nuclear Accident
→ Summary of Reactor Status
→ Deposition/Time Integrated Concentration Model
→ Fukushima Potential Impact on Marine Environment
→ Fukushima Radiological Consequences
→ Watch Video
On Monday, 28 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, provided the following briefing on the current status of nuclear safety in Japan:
1. Current Situation
An earthquake of magnitude 6.5 occurred at on 27 March, 22:23 UTC near the east coast of Honshu. NISA has confirmed that there have been no abnormal radiation readings at the Onagawa nuclear power plant, the closest to the epicentre, whose three units remain in cold shutdown since the earthquake of 11 March. As of 02:30 UTC today, there were no reports of any problems at nuclear plants in Japan related to the latest seismic event.
Overall at the Fukushima Daiichi plant, the situation is still very serious.
NISA informed the Incident and Emergency Centre (IEC) that a meeting is planned with TEPCO to determine the origin and path of water in the turbine buildings of Units 1 to 4. As seen with the contaminated workers, high dose rates in the turbine buildings and contaminated water in the basements can hamper recovery efforts.
The pumping of contaminated water from the basement floor of Unit 1's turbine building into its main condenser is in progress, whereas at Unit 2 that process has not begun because the steam condenser is full. At Unit 3, the pumping of contaminated water and in particular where it is going, are under consideration. The issue is also being examined for Unit 4.
Temperatures measured at the feed water nozzle and at the bottom of the Reactor Pressure Vessel (RPV) continue to decrease slightly at Units 1 and 2, except the temperature at the feed water nozzle of Unit 1's RPV, which has slightly increased to 274 °C.
A positive development is that the pumping of fresh water into the reactor pressure vessel of Unit 1 is to switch from the use of fire trucks to temporary electrical pumps running on offsite power on 29 March. At Unit 2, this switch was carried out on 27 March, with a diesel generator as backup in case offsite power is interrupted. Fresh water is also being injected continuously into the reactor pressure vessel of Unit 3, albeit currently pumped by fire trucks. The switch to temporary electrical pumps for this Unit is planned for today.
On 27 March at Unit 3, water was sprayed into the spent fuel pool using a concrete pump truck, and seawater was also pumped in through the spent fuel cooling system. It is planned to start pumping fresh water into the spent fuel pool tomorrow.
It is also planned to commence pumping freshwater into the spent fuel pool of Unit 4 from tomorrow.
Units 5 and 6 remain in cold shutdown.
At noon today in Japan, the three workers mentioned in previous briefings were released from the National Institute of Radiological Sciences where they had been kept under observation. The result of analyses performed indicates that the level of localised exposure received by two of them is between 2 000 and 3 000 millisievert (i.e. somewhat lower than the previous estimate of 2 000 to 6 000 millisievert).
2. Radiation Monitoring
On 27 March, deposition of iodine-131 was detected in 9 prefectures, and deposition of cesium-137 in 4 prefectures. The highest values were observed in the prefecture of Tochigi with 320 becquerel per square metre for iodine-131 and 73 becquerel per square metre for caesium-137. In the other prefectures where deposition of iodine-131 was reported, on 27 March, the range was from 6.4 to 110 becquerel per square metre. For caesium-137, the range was from 16 to 61 becquerel per square metre. In the Shinjyuku district of Tokyo, the daily deposition of iodine-131 on 27 March was 100 becquerel per square metre, while for caesium-137 it was 36 becquerel per square metre. No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday.
Two IAEA teams are currently monitoring radiation levels and radioactivity in the environment in Japan. One team made gamma dose-rate measurements in the Tokyo and Chiba region at 3 locations. Gamma-dose rates measured ranged from 0.08 to 0.13 microsievert per hour, which is within or slightly above the background. The second team made additional measurements at distances of 30 to 46 km from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.5 to 3 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.02 to 0.3 Megabecquerel per square metre.
New results from the marine monitoring stations 30 km off-shore were received for seawater samples taken on 26 March. The levels decreased at most of the locations. For iodine-131 the concentration results for four monitoring stations are between 6 to 18 becquerel per litre, and for caesium-137 between "below limit of detection" and 16 becquerel per litre. The dose rates measured on the sea surface remain relatively low between 0.04 and 0.1 microsievert per hour.
Samples collected on 26 March 330 metres east of the discharge point showed increasing concentrations. There were found to be 74 000 becquerel per litre for iodine-131, 12 000 becquerel per litre for caesium-137, and 12,000 becquerel per litre for caesium-134.
It is still too early to draw conclusions for expected concentrations in marine food, because the situation can change rapidly. Modelling results show an initial north-eastern transport of liquid releases from the damaged reactors.
Monitoring of iodine-131 and cesium-137 in drinking water is on-going. Iodine-131 has been monitored by the Japanese authorities in 2 of 10 samples taken in the Fukushima prefecture with values of 60 and 90 becquerel per litre. In the Ibaraki prefectures, iodine-131 was detected in 2 of 9 samples, the values were 40 and 90 becquerel per litre. The Japanese limits for the ingestion of drinking water by infants is 100 becquerel per litre.
As far as food contamination is concerned, samples reported from 26 to 27 March in six prefectures (Fukushima, Gunma, Ibaraki, Niigata, Tochigi and Yamagata) reported iodine-131 in asparagus, cabbage, celery, chive, cucumber, eggplant, leek, mushrooms, parsley, tomato, spinach and other leafy vegetables, strawberries and watermelon. One sample of hana wasabi taken on 24 March in Fukushima prefecture was above the regulation values set by the Japanese authorities. Caesium-137 was also measured above the regulation value in the same sample of hana wasabi, but in the remaining five prefectures, caesium-137 was not detected or the results were below regulation values.
The Joint FAO/IAEA Food Safety Assessment Team met with local government authorities in Fukushima on Sunday and discussed issues related to food contamination, including standards and sampling plan designs for radionuclides in food and the environment, radionuclide transfer from soil to plants, and mitigation strategies. The FAO/IAEA team also met with the local authority in Ibaraki prefecture today. They will have meetings with local government officials in Tochigi and Gunma tomorrow.