Fukushima Nuclear Accident Update Log
Updates of 18 March 2011
- Story Resources
- In Focus: Fukushima Nuclear Accident
- Fukushima Nuclear Accident: Information Sheet
- Criteria for Use in Preparedness and Response for a Nuclear or Radiological Emergency
- International Nuclear and Radiological Event Scale (INES)
- IAEA Incident and Emergency Centre (IEC)
- International Seismic Safety Centre (ISSC)
- Response Assistance Network (RANET)
- Japan Nuclear and Industrial Safety Agency (NISA)
On 18 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, briefed both Member States and the media on the current status of nuclear safety in Japan. His opening remarks, which he delivered at 14:00 UTC at the IAEA headquarters in Vienna, are provided below:
1. Current Situation
As I reported yesterday, the situation at the Fukushima Daiichi nuclear power plants remains very serious, but there has been no significant worsening since our last briefing.
The situation at the reactors at Units 1, 2 and 3 appears to remain fairly stable.
Seawater was injected yesterday into Unit 2 and white smoke was again observed through the blown-out panels.
At Unit 3, which was the subject of helicopter water drops yesterday, water cannons have been spraying water on the spent fuel pond and seawater was injected into the reactor pressure vessel.
An important safety concern remains the spent fuel pools at Units 3 and 4. Information is lacking on water levels and temperatures at the spent fuel pools.
Efforts are being made to restore electrical power to the whole site. Another positive development is that diesel generators are providing power for cooling for both Units 5 and 6.
No problems have been reported at the common spent fuel pool. The spent fuel in the pool is fully covered by water.
The Japanese authorities today issued new ratings for the incidents on the IAEA International Nuclear and Radiological Event Scale - INES.
They assess core damage at the Fukushima Daiichi 1, 2 and 3 reactor Units, caused by the loss of all cooling function, as 5 on the INES scale.
The situation at Unit 4, where cooling and water supply in the spent fuel pool have been lost, is rated 3 by the Japanese authorities.
At the Fukushima Daini nuclear power plant, the loss of cooling functions in Units 1, 2 and 4 has also been rated as 3. All reactor Units at Fukushima Daini are now in a cold shut down condition.
2. Radiation Monitoring
As mentioned yesterday, regular dose rate information is now being received from 47 Japanese cities.
Dose rates in Tokyo and other cities remain far from levels which would require action - in other words they are not dangerous to human health.
First measurements in Tokyo by the Agency's newly arrived radiation monitoring team today showed no indication of Iodine-131 or Caesium-137. A second sampling will be carried out overnight.
3. Agency Activities
As you know, the Director General is in Tokyo, where he met the Prime Minister and other senior government ministers as well as the Vice-President of Tepco. The Director General stressed the importance of providing faster and more detailed information about the situation at the nuclear power plants, including to the international community. He also emphasized the importance of Japan working closely with the international community to resolve the crisis.
There was agreement between the Agency and our Japanese counterparts that the Agency mission would focus on radiation measurements and the identification of Japanese needs for a future environmental monitoring programme.
The Agency has started radiation measurements in Tokyo, as I mentioned, and we will move towards the Fukushima region as soon as possible. The Japanese counterparts confirmed their willingness to further strengthen their cooperation with the Agency and make available measurements made by TEPCO and the Ministry of Education, Culture, Sports, Science and Technology.
The Director General plans to brief the Agency's Board of Governors on his return from Japan.
Following our request yesterday, the CTBTO informed us today that data from its radionuclide monitoring stations will be made available to the Agency with immediate effect. On behalf of the Director General, I express my thanks to CTBTO Executive Secretary, Mr. Tibor Toth.
The International Civil Aviation Organization, in consultation with the Agency and a number of other international organizations, said today that international flight and maritime operations can continue normally into and out of Japan's major airports and sea ports and there is no medical basis for imposing additional measures to protect passengers. This will be kept under review.
Agency staff continue to work around the clock. We intend to hold another Technical Briefing and press conference at the same time tomorrow, Saturday.
→ Summary of Reactor Unit Status, by Graham Andrew
→ Technical Briefing of Nuclear Safety Aspects of Situation in Japan, by James Lyons
→ Technical Briefing on Radiological Situation in Japan, by Renate Czarwinksi
Fukushima Nuclear Accident Update (18 March 2011, 12:25 UTC)
Japanese authorities have informed the IAEA that, prior to the earthquake of 11 March, the entire fuel core of reactor Unit 4 of the Fukushima Daiichi nuclear power plant had been unloaded from the reactor and placed in the spent fuel pond located in the reactor's building.
Contrary to several news reports, the IAEA to date has NOT received any notification from the Japanese authorities of people sickened by radiation contamination.
In the report of 17 March 01:15 UTC, the cases described were of people who were reported to have had radioactive contamination detected on them when they were monitored.
Fukushima Nuclear Accident Update (18 March 2011, 10:15 UTC)
Japanese authorities have informed the IAEA that new INES ratings have been issued for some of the events relating to the nuclear emergency at the Fukushima Daiichi and Daini nuclear power plants.
Japanese authorities have assessed that the core damage at the Fukushima Daiichi 2 and 3 reactor Units caused by loss of all cooling function has been rated as 5 on the INES scale.
Japanese authorities have assessed that the loss of cooling and water supplying functions in the spent fuel pool of the Unit 4 reactor has been rated as 3.
Japanese authorities have assessed that the loss of cooling functions in the reactor Units 1, 2 and 4 of the Fukushima Daini nuclear power plant has also been rated as 3. All reactor Units at Fukushima Daini nuclear power plant are now in a cold shut down condition.
Addition of 12:45 UTC
Japanese authorities have assessed that the core damage at the Fukushima Daiichi 1 reactor unit caused by the loss of all cooling function has been rated as 5 on the INES scale.
This is an upgrade from a previous rating of 12 March as 4 on the INES scale, which was based on an abnormal rise of radioactive dose rate at the site boundary.
Fukushima Nuclear Accident Update (18 March 2011, 06:10 UTC)
Temperature of Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant - Updated
Spent fuel removed from a nuclear reactor is highly radioactive and generates intense heat. Nuclear plant operators typically store this material in pools of water that cool the fuel and shield the radioactivity. Water in a spent fuel pool is continuously cooled to remove heat produced by spent fuel assemblies. According to IAEA experts, a typical spent fuel pool temperature is kept below 25 °C under normal operating conditions. The temperature of a spent fuel pool is maintained by constant cooling, which requires a constant power source.
Given the intense heat and radiation that spent fuel assemblies can generate, spent fuel pools must be constantly checked for water level and temperature. If fuel is no longer covered by water or temperatures reach a boiling point, fuel can become exposed and create a risk of radioactive release. The concern about the spent fuel pools at Fukushima Daiichi is that sources of power to cool the pools have been compromised.
Concern about spent fuel storage conditions has led Japanese officials to drop and spray water from helicopters and trucks onto Unit 3 at Fukushima Daiichi nuclear power plant (See earlier update).
Japan's Nuclear and Industrial Safety Agency has reported increasing temperatures in the spent fuel ponds at Units 5 and 6 since 14 March. An emergency diesel generator at Unit 6 is now powering water injection into the ponds at those Units, according to NISA.
The IAEA can confirm the following new information regarding the temperatures of the spent nuclear fuel pools at Units 4, 5 and 6 at Fukushima Daiichi nuclear power plant:
|13 March, 19:08 UTC:||84 °C|
|17 March, 03:00 UTC:||64.2 °C|
|17 March, 18:00 UTC:||65.5 °C|
|17 March, 03:00 UTC:||62.5 °C|
|17 March, 18:00 UTC:||62.0 °C|
The IAEA is continuing to seek further information about the water levels, temperature and condition of all spent fuel pool facilities at the Fukushima Daiichi nuclear power plant.