IAEA update on Japan Earthquake

IAEA Briefing on Fukushima Nuclear Accident (7 April 2011, 18:00 UTC)

Presentation:
→ Summary of Reactor Status
→ Radiological Monitoring and Consequences
→ Status of Fukushima Units
→ Marine Environment Monitoring

1. Current Situation

Overall, the situation at the Fukushima Daiichi plant remains very serious although there are early signs of recovery in some functions such as electrical power and instrumentation.

On 6th April it was reported that the leakage of water from the sidewall of the pit closest to the sea has stopped after coagulation agents (liquid glass) were injected into the holes drilled around the pits. Work continues to prevent further releases to the sea.

According to the TEPCO Press Release of 4th April, approximately 10,000 T of water from the radioactive waste treatment plant and 1,500 T of subsurface waters stored in the sub drain pits of Unit 5 and 6 are being discharged to the sea to provide room to store water with higher levels of radioactivity in a safer manner. TEPCO has estimated that these discharges would increase the effective dose to a member of the public by 0.6 mSv, if he/she were to eat seaweed and seafood from 1 km from the discharge point every day for a year. It should be noted however that the movements of all ships, including fishing boats, are restricted within a 30km zone from the NPP.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. Fresh water is being injected continuously into the RPVs through the fire extinguisher lines in Units 2 and 3 at indicated rates of 8 m3/h and 7 m3/h respectively using a temporary electric pump with off-site power.

As of 6th April, TEPCO started injecting nitrogen gas to Unit 1 containment vessel to provide an inerted atmosphere to reduce the possibility of hydrogen combustion within the containment vessel.

On Unit 1 the indicated temperature at the feed water nozzle of the RPV is 224° and at the bottom of RPV it is 117°. Instrumentation ‘B’ for Reactor Pressure indicates that the pressure in the RPV is increasing and instrumentation ‘A’ indicates that it has stabilized. NISA has indicated that some instruments in the reactor vessel may not be working properly. Drywell pressure has increased slightly due to the injection of nitrogen. In Unit 2 the indicated temperature at the feed water nozzle of the RPV is stable at 143°. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. The indicated temperature at the feed water nozzle of the RPV in Unit 3 is 88° and at the bottom of RPV is about 115°.

Additional water was injected via the Spent Fuel Cooling System line to the spent fuel pool by a temporary pump on 4th April.

There has been no change in status on Units 4, 5, 6 and the Common Spent Fuel Storage Facility

2. Radiation monitoring

On 6th April, low levels of deposition of both I-131 and Cs-137 were detected in 4 and 6 prefectures respectively. The values reported for I-131 ranged from 3.4 to 10 becquerels per square metre, for Cs-137 from 4.9 to 19 becquerels per square metre. Gamma dose rates continue decreasing . There is no significant change in gamma dose rates reported for 6th April compared to yesterday.

As of 5th April, I-131 and Cs-134/137 was detectable in drinking water in a small number of prefectures. All values were well below levels that would initiate recommendations for restrictions of drinking water. As of 6th April, one restriction for infants related to I-131 (100 Bq/l) is in place as a precautionary measure in only one village of the Fukushima prefecture.

TEPCO is responsible for near-shore sampling, taking samples of surface seawater. Samples near discharge areas are collected daily. Until 3rd April a general decreasing trend was observed.  However, after the discharge of contaminated water at 4th April, an increase from about 11 kBq/l as measured at 09:00 to 41 kBq/l at 14:00 for I-131; from 5.1 kBq/l at 09:00 to 19 kBq/l for both, Cs-134 and Cs-137 at 14:00 was recorded. On the 5th April a decrease was observed as compared to the previous day, with seawater concentration of 5 kBq/l for Cs-137 and 11 kBq/l for I-131.

Since 4th April TEPCO added 3 new sampling points 15 km offshore, in addition to the already established 3 sampling points at the same distance, this resulting in a total of 6 sampling points situated along a north-south transect at a distance of 15 km from the coast.

Levels of radionuclides reported at these l°ations for the 5th of April are in the range 57 - 200 Bq/l for I-131, 18 - 310 Bq/l for Cs-134 and 18 - 320 Bq/l for Cs-137.

There were no new data for 30 km off shore monitoring, carried out under the responsibility of MEXT, compared to yesterday’s briefing.

On 6th April the marine expert from the IAEA Environment Laboratories Monaco completed his mission in Japan. From the 2nd to 4th April he embarked on the research vessel MIRAI to observe the sampling conducted 30 km offshore. He visited the JAEA laboratory in Tokai where the gamma spectrometric analyses are performed. He briefed representatives of the Japanese Government

Since our written briefing of yesterday, data related to food contamination were reported on 6th April by the Japanese Ministry of Health, Labour and Welfare. These reported analytical results covered a total of 78 samples taken on 3rd April (2 samples), 4th April (39 samples), 5th April (35 samples) and 6th April (2 samples). Analytical results for 52 of the 78 samples for various vegetables, spinach and other leafy vegetables, fruit (strawberry) and unpr°essed raw milk in eight prefectures (Fukushima, Gunma, Hyogo, Ibaraki, Kanagawa, Niigata, Saitama and Yamagata) indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. However, it was reported that analytical results for 26 of the total 41 samples taken in Fukushima prefecture for various vegetables, spinach and other leafy vegetables indicated that I-131 and/or Cs-134/Cs-137 exceeded the regulation values set by the Japanese authorities.

On 5th April, the Japanese Ministry of Health, Labour and Welfare issued a press release indicating that a new provisional regulation value was set for I-131 at a limit of 2000 Bq/kg in fishery products.

As of 4th April, food restrictions (distribution and/or consumption) are in place in four prefectures (Fukushima, Ibaraki, T°higi, and Gunma) and in certain l°ations in Chiba prefecture (Katori City, Tako Town and Asahi City).

In Fukushima, there are restrictions on the consumption of leafy vegetables, headed and non-headed leafy vegetables (e.g. spinach, komatsuna, cabbage), and flower-headed brassicas (br°coli, cauliflower). There are also restrictions on the distribution of headed and non-headed leafy vegetables, flower-headed brassicas (including turnips), spinach, kakina and unpr°essed raw milk produced in the prefecture.

In Ibaraki, there are restrictions on the distribution of unpr°essed raw milk, parsley, spinach and kakina produced in the prefecture.

In Chiba, there are restrictions on the distribution of spinach produced in Katori City and Tako Town. There are also restrictions on the distribution of spinach, chingensai, shungiku, sanchu, celery and parsley produced in Asahi City.

In Gunma and T°higi, there are restrictions on the distribution of spinach and kakina produced in these prefectures.

3. IAEA Activities

The two agency experts in BWR technology are in Japan to have a direct exchange of views with the Japanese counterparts. They met with officials of NISA, TEPCO, the Japanese Atomic Energy Commission and the Nuclear Safety Commission. They visited the off-site emergency response center and the Fukushima Daiichi site. A third agency expert will join the team in Tokyo to have follow-up meetings with TEPCO and NISA at the end of the week.

The following countries have submitted monitoring data and/or links to national websites where data is available: Austria, Belgium, Bulgaria, Canada, China, Finland, France, Greece, Iran, Ireland, Italy, Malaysia, Poland, Romania, Russian Federation, Singapore, Spain, Sweden, Switzerland, and Ukraine.

IAEA Update: New earthquake in Japan (7 April, 17:30 UTC)

The IAEA confirms that an earthquake occurred in Japan at 14:32 UTC 7 April. The IAEA International Seismic Safety Centre has rated it as a 7.1 magnitude, revised from an initial 7.4 magnitude. The epicenter of the earthquake was 20 km from the Onagawa nuclear power plant and approximately 120 km from the Fukushima Daiichi and Daini nuclear power plants.

The IAEA has been in contact with NISA and can confirm the status of the following nuclear facilities:

Fukushima Daiichi Nuclear Power Plant
NISA confirms that no changes have been observed at the on-site radiation monitoring posts. The injection of water into the reactor pressure vessels of Units 1, 2 and 3 was not interrupted.

Fukushima Daini Nuclear Power Plant
NISA confirms that no changes have been observed of the readings at the on-site radiation monitoring posts.

Onagawa Nuclear Power Plant
All reactors have been in cold shutdown since the 11 March earthquake.

NISA has confirmed that two out of the three lines supplying off-site power to the site were lost following the 7 April earthquake. Off-site power continues to be supplied through the third line.

Cooling of the spent fuel pool was temporarily lost, but has subsequently been restored.

No change has been observed in the readings from the on-site radiation monitoring post. The status of the plant is currently being checked.

Tokai Daini Nuclear Power Plant
Tokai Daini nuclear power plant remains in cold shutdown since the 11 March earthquake. No abnormality has been observed.

Higashidori Nuclear Power Plant
NISA has confirmed that the Higashidori NPP was shutdown and in a maintenance outage at the time of the 7 April earthquake. Off-site power has been lost. Emergency power supply to the site is operating. All the fuel had been removed from the reactor core and stored in the spent fuel pool. Cooling of the spent fuel pool is operational.

Tomari Nuclear Power Plant (in Hokkaido)
At the time of the 7 April earthquake Tomari Unit 1 and Unit 2 were in operation. Following the 7 April earthquake, the Hokkaido Electric Power Company reduced the generating power to 90% of capacity.

Rokkasho Reprocessing Plant
NISA confirms that Rokkasho Reprocessing Plant and uranium enrichment facility lost off-site power. Emergency power supply to the site is operating.

The IAEA will issue further information as soon as it becomes available.

IAEA Briefing on Fukushima Nuclear Accident (30 March 2011, 16.30 UTC)

Presentations:
→ IAEA Briefing on Fukushima Nuclear Accident, 30 March 2011
→ Summary of Reactor Status, 30 March 2011
→ Fukushima Contaminated Water Flow Illustration, 30 March 2011
→ Fukushima Impact on Marine Environment, 30 March 2011
→ Fukushima Nuclear Power Plant Photos, 29 March 2011
→ Watch Video

On Wednesday, 30 March 2011, the IAEA provided the following information on the current status of nuclear safety in Japan.

1. Current Situation

Overall at the Fukushima Daiichi plant, the situation remains very serious.

With respect to the water that is present in the turbine buildings. In Unit 1, water has continued to be pumped into the condenser with 3 pumps (6.5 ton/hour each) and the water level has reduced from 40cm to 20cm. In Unit 2 from 07.45 UTC, pumping of water from the Condensate Storage Tank into the Surge Tank was started so that the that condenser can be drained to the Condensate Storage Tank and contaminated water can be pumped out from the Turbine building into the condenser. The same process of pumping the water from the Condensed Water Storage Tank into the Surge Tank was started on Unit 3 at 08.40 UTC on 28 March.

Near the Unit 3 building, 3 workers spilled water over themselves when removing a flange from seawater pipes on the residual heat removal system (RHR). After showering, contamination was not detected.

Fresh water has been continuously injected into the Reactor Pressure Vessel (RPV) through feed-water line at an indicated flow rate of 8.0 m3/h at Unit 1. The pumping of freshwater into the RPV has been switched from fire trucks to temporary electrical pumps with diesel generator. At Units 2 and 3 fresh water is being injected continuously through the fire extinguisher line at an indicated rate of 7 m3/h using a temporary electric pump.

The indicated temperature at the feed water nozzle of the RPV of Unit 1 has decreased from 323 °C to 281 °C and at the bottom of RPV remained stable at 134 °C. There is a corresponding decrease in Drywell pressure. At Unit 2 the indicated temperature at the feed water nozzle of the RPV has increased from 154 °C to 177 °C and at the bottom of RPV has increased from 78 °C to 88 °C. Indicated Drywell pressure remains at atmospheric pressure. For Unit 3 the indicated temperature at the feed water nozzle of the RPV is about 75 °C and at the bottom of RPV is about 116 °C. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation.

With respect to the Spent Fuel Pools, it was planned to commence the pumping of water into the Unit 1 Spent Fuel Pool by concrete pumping truck from 29 March. Also, on 29 March pumping of fresh water into the Unit 2 spent fuel pool commenced via a temporary electrical pump. The temperature of the spent fuel pool is 46 °C as of 19:00 UTC, 29 March. For Unit 4 it was planned to commence pumping freshwater into the spent fuel pool on March 29. The IAEA has not received information on implementation of spraying activities in units 1 and 4.

Units 5 and 6 remain in cold shutdown

2. Radiation Monitoring

The majority of the recently measured radioactivity levels in drinking water are being reported below the levels established by the Japanese authorities which are 100 Bq/L of I-131 for infants; 300 Bq/L for adults and 200 Bq/L of Cs-137 for infants and adults. Previously imposed recommendations for restrictions on drinking water are being lifted in most of the affected locations. As of 28 March, recommendations for restrictions based on I-131 concentration remain in place in one village in the Fukushima prefecture. In three other locations of the Fukushima prefectures, restrictions continue to apply for infants only.

Two IAEA teams are currently monitoring radiation levels and radioactivity in the environment in Japan. On 29 March, one team made gamma dose-rate measurements in the Tokyo region at 8 locations. Gamma-dose rates measured ranged from 0.02 to 0.19 microsievert per hour, which is within or slightly above the background.

The second team made additional measurements at distances of 32 to 62 km, at directions North to Northwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.5 to 6.8 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.05 to 0.45 Megabecquerel per square metre.

Based on measurements of I-131 and Cs-137 in soil, sampled from 18 to 26 March in 9 municipalities at distances of 25 to 58 km from the Fukushima Nuclear Power Plant, the total deposition of iodine-131 and cesium-137 has been calculated. The results indicate a pronounced spatial variability of the total deposition of iodine-131 and cesium-137. The average total deposition determined at these locations for iodine-131 range from 0.2 to 25 Megabecquerel per square metre and for cesium-137 from 0.02-3.7 Megabecquerel per square metre. The highest values were found in a relatively small area in the Northwest from the Fukushima Nuclear Power Plant. First assessment indicates that one of the IAEA operational criteria for evacuation is exceeded in Iitate village. We advised the counterpart to carefully assess the situation. They indicated that they are already assessing.

As far as food contamination is concerned, 35 samples taken from 25-29 March, and reported on 29 March, for various vegetables, fruit (strawberry), seafood, pork and unprocessed raw milk in nine prefectures (Chiba, Gunma, Ibaraki, Kanagawa, Nagano, Niigata, Saitama, Tochigi and Yamagata), stated that results for iodine-131, caesium-134 and caesium-137 were either not detected or were below the regulation values set by the Japanese authorities.

The Joint FAO/IAEA Food Safety Assessment Team met with local government officials in Tochigi prefecture on 29 March and provided advice related to contamination of food and the environment.

Local government officials briefed the FAO/IAEA Team on the extent of contamination in Tochigi, the principle agricultural products affected, the main production areas and production methods (greenhouses, open-air), levels of contamination found (principally in air, tap/ground water and vegetables) and imminent plans to monitor soil contamination. A field visit also took place to a spinach producer outside Utsunomiya City.

Based on these latest discussions with the Tochigi authorities, it is apparent that the focus of the Joint FAO/IAEA mission has changed to some extent from the mechanisms of contamination to remediation strategies and techniques related to plant and animal production, food traceability and water/soil characterization.

The FAO/IAEA team is also meeting with the local government officials in Gunma prefecture today.

No new results from the marine monitoring stations 30 km off-shore as well as from close to the discharge, were reported since 27 March.

One IAEA staff member of the Monaco marine laboratory will fly to Japan on 31 March in order to join the Japanese team assessing marine environment.

The IAEA continues activities under the Joint Radiation Emergency Management Plan of the International Organisations through regular video/teleconferences. As of 30 March the WHO liaison officer is working in the IEC.

In response to the request for data on measurement, the IEC has received information from Singapore. The Singapore Authorities have sent reports on measurements in food imported from Japan (cabbages). Some samples were over the Codex Alimentarius values recommended for international trade. In Singapore no increase in gamma dose rates have been observed and no fission products have been found in air samples.

IAEA Briefing on Fukushima Nuclear Accident (27 March 2011, 13:30 UTC)

1. Current Situation

The situation at the Fukushima Daiichi plant remains very serious.

The restoration of off-site power continues and lighting is now available in the central control rooms of Units 1, 2 and 3. Also, fresh water is now being injected into the Reactor Pressure Vessels (RPVs) of all three Units.

Radiation measurements in the containment vessels and suppression chambers of Units 1, 2 and 3 continued to decrease. White “smoke” continued to be emitted from Units 1 to 4.

Pressure in the RPV showed a slight increase at Unit 1 and was stable at Units 2 and 3, possibly indicating that there has been no major breach in the pressure vessels.

At Unit 1, the temperature measured at the bottom of the RPV fell slightly to 142 °C. At Unit 2, the temperature at the bottom of the RPV fell to 97 °C from 100 °C reported in the Update provided yesterday. Pumping of water from the turbine hall basement to the condenser is in progress with a view to allowing power restoration activities to continue.

At Unit 3, plans are being made to pump water from the turbine building to the main condenser but the method has not yet been decided. This should reduce the radiation levels in the turbine building and reduce the risk of contamination of workers in the turbine building restoring equipment.

No notable change has been reported in the condition of Unit 4.

Water is still being added to the spent fuel pools of Units 1 to 4 and efforts continue to restore normal cooling functions.

Units 5 and 6 remain in cold shutdown.

We understand that three workers who suffered contamination are still under observation in hospital.

2. Radiation Monitoring

Dose rates at the Fukushima site continue to trend downwards.

In 28 of the 45 prefectures for which data are available, no deposition of radionuclides was detected in the period 18 to 25 March. In seven of the other 17 prefectures, the estimated daily deposition was less than 500 becquerel per square metre for iodine-131 and less that 100 becquerel per square metre for caesium-137.

On 26 March, the highest values were observed in the prefecture of Yamagata: 7500 becquerel per square metre for iodine-131 and 1200 becquerel per square metre for caesium-137. In the other prefectures where deposition of iodine-131 was reported, the daily range was from 28 to 860 becquerel per square metre. For caesium-137, the range was from 2.5 to 86 becquerel per square metre.

In the Shinjyuku district of Tokyo, the daily deposition of iodine-131 on 27 March was 220 becquerel per square metre, while for caesium-137 it was 12 becquerel per square metre.

No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday. In general, gamma–dose rates tend to decrease due to the decay of short-lived radionuclides such as iodine-131.

Two IAEA teams are currently monitoring in Japan. One team made gamma dose-rate measurements in the Tokyo region at 8 locations. Gamma-dose rates measured ranged from 0.08 to 0.15 microsievert per hour, which is within or slightly above the normal background. The second team made additional measurements at distances of 30 to 41 km from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.9 to 17 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.03 to 3.1 Megabecquerel per square metre.

The first results of aerial surveys of gamma dose rates by the Japanese authorities have been received by the Incident and Emergency Centre. These are being analysed and will be presented when more detailed data have been received.

New data from monitoring of the marine environment, carried out from 24 March 22:55 UTC to 25 March 03:32 UTC about 30 km offshore, show a decrease in both caesium-137 and iodine 131. The contamination at these locations is influenced by aerial deposition of fallout as well as by the migration of contaminated seawater from the discharge points at the reactor. The measured radiation doses rates above the sea remain consistently low (between 0.04 and 0.1 microsievert per hour). The first results of model predictions received from the SIROCCO Group at the University of Toulouse are being assessed.

Recommendations relating to the restriction of drinking water consumption, based on measured concentrations of iodine-131, remain in place in seven locations (in one location for both adults and infants, and in six locations for infants).

As far as food contamination is concerned, samples taken from 23 to 25 March in five prefectures showed iodine-131 in unprocessed raw milk, but the levels were far below the regulation values set by the Japanese authorities. Caesium-137 was also detected in samples of unprocessed raw milk taken on 23 March in Chiba prefecture, but at levels far below the Japanese regulation values. Caesium-137 was not detected in any of the samples taken from 24-25 March in the other four prefectures.

Based on samples taken on 22 and 24-25 March, three prefectures (Chiba, Ibaraki and Tochigi) reported iodine-131 in celery, parsley, spinach, and other leafy vegetables above the regulation values set by the Japanese authorities. Caesium-137 was also detected above the regulation values in one sample of spinach taken on 24 March in Tochigi prefecture, but in the remaining two prefectures, the results were below regulation values.

The Joint FAO/IAEA Food Safety Assessment Team arrived in Tokyo on Saturday. It will meet regulatory officials in various prefectures where food contamination has been detected. The team left for Fukushima early today. The Mission will assist and provide advice on sampling protocols, analytical procedures, data collected to date, and actions taken by the Japanese authorities for the control of contaminated foods.

→ IAEA Summary of Fukushima Reactor Unit Status

Fukushima Daiichi Nuclear Accident Update (27 March 2011, 9:00 UTC)

According to the Japanese Prime Minister's office, TEPCO has begun work to remove water that has accumulated in the turbine buildings at the Fukushima Daiichi nuclear power plant. Workers have started to remove water from the Unit 1 turbine building to its main condenser and are making preparations to do the same at Unit 2. (A main condenser's function in a nuclear power plant is to condense and recover steam that passes through the turbine.) Work to remove water from the turbine buildings in Units 3 and 4 is currently under consideration.

Removal of water from the turbine buildings is an important step to continue power restoration to the plant.

The IAEA is seeking further updates from Japanese authorities on the progress of this process and will update as information becomes available.

Fukushima Daiichi Nuclear Accident Update (27 March, 03:00 UTC)

As previously reported, three workers at the Fukushima Daiichi nuclear power plant were exposed on 24 March to elevated levels of radiation. The IAEA has received additional information on the incident from the Japanese authorities.

For two of the three workers, significant skin contamination over their legs was confirmed. The Japanese authorities have stated that during medical examinations carried out at the National Institute of Radiological Sciences in the Chiba Prefecture, the level of local exposure to the workers’ legs was estimated to be between 2 and 6 sieverts.
While the patients did not require medical treatment, doctors decided to keep them in hospital and monitor their progress over coming days.

Fukushima Daiichi Nuclear Accident Update (27 March, 01:15 UTC)

Brief Update on State of Fukushima Daiichi Reactors

AC Power-Units 1 to 4

The restoration work of off-site (i.e., grid) power is still in progress. Off-site power is now connected to Units 1 to 4.
Power distribution panels in the Power Centres of Units 2 and 4 have been connected to the off-site electricity supply, but individual components are still being checked prior to being energised.
The lighting in units 1, 2 and 3 control rooms has been restored. Some instrumentation was recovered for units 1, 2 and 4. However, due to the extent of damage inflicted by the earthquake and tsunami, at present it is not possible to estimate when the equipment may be returned to service.

AC Power-Units 5 and 6

Off-site power has been restored.

Unit 1

Fresh water continues to be injected into the reactor pressure vessel.
As of 23:00 UTC 25 March, white smoke was confirmed to be emanating continuously from the reactor building.
Water sample taken from the stagnant water on the basement floor of the turbine building shows the presence of iodine-131, cesium-137 and cesium-134 to a level comparable to that measured in the turbine building of unit 3 where three workers were exposed to elevated levels of radiation on 24 March.

Unit 2

Fresh water continues to be injected into the reactor pressure vessel.
As of 23:00 UTC 25 March, white smoke was confirmed to be emanating continuously from the reactor building.
The spent fuel pool temperature increased and then stabilized at 57 degrees Celsius as of 00:30 UTC 26 March.

Unit 3

Fresh water is being injected into the reactor pressure vessel.
The temperature at the bottom of reactor pressure vessel has decreased to 100.4 degrees Celsius at 13:00 UTC 26 March. Seawater injection to the spent fuel pool is on-going.
White smoke emanating from the reactor building was still being observed as of 23:00 UTC 25 March.
The dose rate in the reactor containment vessel and suppression chamber continued to decrease to 36.1 sieverts per hour and 1.4 sieverts per hour, respectively, as of 13:00 UTC 26 March.

Unit 4

From March 22 to March 25, 130 to 150 tonnes of seawater was poured into the spent fuel pool each day using a concrete pump. Sea water was also poured in through spent fuel cooling system from 21:05 UTC 24 March to 01:20 25 March.
White smoke was still being observed coming from the reactor building as of 23:00 UTC 25 March.

Unit 5

The reactor remains in cold shutdown. Off-site power has been restored. The reactor water temperature increased to 43.8 degrees Celsius.
The temperature in the spent fuel pool increased to 42.8 degrees Celsius as of 02:00 UTC 26 March.

Unit 6

The reactor remains in cold shutdown. Off-site power has been restored. The reactor pressure vessel water temperature decreased to 21.3 degrees Celsius.
The spent fuel pool water temperature has slightly increased to 30.0 degrees Celsius.

Fukushima Daiichi Nuclear Accident Update (26 March 2011, 10:30 UTC)

IAEA Sends Second and Third Teams to Japan to Aid Response to Nuclear Emergency

The IAEA has dispatched additional teams to Japan to assist in the response to the Fukushima Daiichi nuclear power plant emergency.

On 24 March, a team of IAEA specialists travelled to Japan, where they will continue efforts to supplement Japan's radiation monitoring efforts. Team members include worker radiation protection experts and safeguards department officials.

On 25 March, a joint IAEA/Food and Agriculture Organization team departed Vienna. The three-person team included the Head of the IAEA Food and Environmental Protection Laboratory, an IAEA soil scientist, and an FAO food safety specialist from FAO's headquarters in Rome.

This food safety assessment team will provide advice and assistance on sampling and analytical strategies and will help interpret Japanese monitoring data.

Fukushima Daiichi Nuclear Accident Update (26 March, 05:15 UTC)

Brief Update on State of Fukushima Daiichi Reactors

Japanese authorities today confirmed a number of developments at the nuclear reactors at Fukushima Daiichi.

Unit 1

Workers have restored lighting in the control room and have recovered some instrumentation. As of 25 March, fresh water is now being pumped into the reactor pressure vessel (RPV) instead of seawater.

Unit 2

Seawater injection into the reactor pressure vessel continues, and RPV pressures remain stable.

Unit 3

Workers are now pumping fresh water into the RPV, while seawater is pumped into the spent fuel pool. In addition, firefighters sprayed water into the reactor building yesterday from the outside.

Unit 4

With no fuel in the RPV, concerns remain focused on the condition of the spent fuel pool, and workers continued to use a concrete pump truck to pour water into the pool from above while pumping seawater into the pool through the fuel pool cooling line.

Units 5 and 6

Both reactors have achieved safe, cold shutdown, and their fuel pool temperatures have stabilised at acceptable levels.

Fukushima Daiichi Nuclear Accident Update (26 March, 01:30 UTC)

Radioactive Materials Found in Japanese Seawater Sampling -- UPDATED

Japanese authorities today reported data on radiation samples collected 30 kilometres off shore of the Fukushima Daiichi nuclear power plant on 24 March, and the levels of iodine-131 and cesium-137 showed slight variations from data collected at the same locations on 23 March (see previous update.

A vessel from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) collected water samples at eight points 30 kilometres from the coastline and found measurable concentrations of iodine-131 and cesium-137. The iodine concentrations measured were about at Japanese regulatory limits, and the cesium levels were well below those limits.

The IAEA’s Marine Environmental Laboratory in Monaco has received the data and offered this preliminary analysis:

Dilution, both into deeper layers and by dispersion along the prevailing ocean currents will lead to a rapid decrease of the initial surface contamination.

For the short term, iodine-131 will be the relevant radionuclide as far as doses are concerned, but for the long term, cesium-137 will be the more important radionuclide in the marine environment. It will be possible to follow this nuclide over long distances for several years.

It can be expected that radionuclides will take months or years to reach other shores of the Pacific. The main transport of contamination takes place by atmospheric transport over long distances.

IAEA Briefing on Fukushima Nuclear Accident (25 March 2011, 15:30 UTC)

On Friday, 25 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, provided the following information on the current status of nuclear safety in Japan.

1. Current Situation

There has not been much change at the Fukushima Daiichi plant over the last 24 hours. Some positive trends are continuing, but there remain areas of uncertainty that are of serious concern.

Unit 1 is with offsite AC power to the lighting of its central control room and to some of its instrumentation. Unit 3 now also has lighting to its central control room, but not power to its instrumentation. It remains too early to evaluate how much instrumentation may effectively be recovered at Units 1, 2, 3 and 4.

Reactor pressure is decreasing at Unit 1 and so is seawater injection. On the other hand, pressure readings in the reactor pressure vessels remain unreliable in Unit 2 and have become unreliable in Unit 3.

The temperature at the feed-water nozzle of the reactor pressure vessel continues to decrease (to 205 °C) at Unit 1, and at Unit 3 (42.8 °C), and it remains stable at Unit 2 (105 °C).

The dose rates in the containment vessel and suppression chamber have continued to decrease at Unit 1, and remained stable at Unit 2.

At Unit 3, radiation exposure of three TEPCO subcontracting workers has been confirmed. They were working in the basement, with contaminated water on the floor. Two of them were transferred to hospital with contamination of their feet.

There are no significant developments to report at Unit 4, where water spraying continues.

Units 5 and 6 remain in comparatively good condition. Temperatures at both, which had risen when the cooling pumps were briefly shut down in order to switch to off-site power, temperatures have since been restored to lower levels, and both units are still in cold shutdown. For the same reasons, a brief rise in temperature also occurred at the Common Spent Fuel Pool on 24 March.

2. Radiation Monitoring

On-site radiation monitoring at the Daiichi NPP indicates that dose rates continue to decrease.

Deposition of radioactivity is monitored daily by Japanese authorities in all 47 prefectures. From 23 March to 24 March, additional deposition has been detected in 7 of the 47 prefectures. Considerable variations are observed, the deposition at this day ranged from 42 to 16,000 Becquerel per square metre for iodine-131; the highest value determined for caesium-137 was 210 Becquerel per square metre. For the Shinjuku district of Tokyo, the deposition of iodine-131 on this day increased by 13,000 Becquerel per square metre, and the caesium-137 deposition by 160 Becquerel per square metre.

As far as the marine environment is concerned, sampling of air and seawater continues to be carried out by the Japanese Ministry of Education, Culture, Sport, Science and Technology (MEXT). Results are sent to the IAEA Monaco laboratory for assessment.

Measurements in the marine environment have been carried out 30 km off-shore and 330 metres from the discharge points on 23 March and repeated the next day. The results made available up to 25 March indicate concentrations of iodine-31 (some 80 becquerel/litre) and caesium-137 (about 26 becquerel/litre). This contamination is most likely due to atmospheric fallout rather than just ocean currents. Dilution in the ocean is expected to decrease rapidly this initial surface contamination. Caesium-137 will be more important over the long term owing to its half-life (30 years) compared to that of iodine-131 (8 days). Modelling of the dispersion of these radionuclides has been started, and the first results are becoming available. Marine dispersion will of course be much slower than atmospheric transport.

Since yesterday, additional data has been made available by the Japanese authorities concerning radionuclide concentrations in milk, vegetables and drinking water.

Levels of iodine-131 exceeded levels recommended by the Japanese authorities in five raw milk samples taken in Fukushima Prefecture, and exceeded levels of iodine-131 and cesium-137 in one vegetable (mizuna) sampled in Ibaraki Prefecture.

Monitoring of drinking water is on-going, iodine-131 in drinking water was detected in 13 prefectures, caesium-137 was detected in 6 of the 47 prefectures. During the period of 19 to 23 March, all results remained below the limits set by the Japanese government. However, permissible levels of iodine-131 were exceeded in drinking water samples taken in the Fukushima and Ibaraki Prefectures and in Tokyo from 17 to 23 March. More positively, the iodine-131 levels in drinking water for Tokyo are now below limits for consumption for infants recommended by the Japanese authorities and restrictions have been lifted.

As a result of food monitoring where contamination exceeded the levels recommended by the Japanese authorities, current restrictions on the distribution of milk are in place in 2 prefectures (Fukushima, Ibaraki) and on the distribution of certain vegetables in 4 prefectures (Fukushima, Ibaraki, Tochigi, Gunma). This regulatory approach is to prevent food contaminated with radioactivity above these limits entering the market and thereby, ensure the safety of foods. On 23 March, the Japanese authorities requested sampling of agricultural products in 6 neighbouring prefectures (Miyagi, Yamagata, Saitama, Chiba, Niigata and Nagano). This request for further food monitoring covers the same types of foods currently under restriction.

The joint FAO/IAEA food safety mission is currently travelling to Japan.

On 25th March, the IAEA radiation monitoring team made additional measurements at distances from 34 to 62 km from the Fukushima nuclear power plant. At these locations, the dose rate ranged from 0.73 to 8.8 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.07 to 0.96 Megabecquerel per square metre.

Director General Amano had a video conference today with the UN Secretary General and the Heads of a number of other UN system organizations concerning the accident. In addition, close coordination led by the IAEA through the Joint Radiation Emergency Management Plan of International Organizations (JPLAN) continues.

Fukushima Daiichi Nuclear Accident Update (25 March, 15:45 UTC)

Japanese authorities have informed the IAEA that on March 24, examinations of the thyroid glands in 66 children (14 of which are infants) were conducted near the evacuation area around the Fukushima nuclear plant. The exams were conducted at the Kawamata Town Health Center (40-50 kilometres from Fukushima Daiichi NPP) and Kawamata Town Yamakiya Branch Office (30-40 kilometres from Fukushima Daiichi NPP).

According to a 25 March 2011 Nuclear and Industrial Safety Agency press release, the results of the examinations indicated that the dose rate "of all the 66 children including 14 infants from 1 to 6 years old had no big difference from the level of background and was at the level of no problem in light of the view of Nuclear Safety Commission."

Regarding developments at the Fukushima Daiichi nuclear power plant, 'white smoke' was reported at Units 1, 2 and 4 from 21:20 UTC on 24 March. Sea water injection to Units 1, 2, 3 and 4 continues as of 23:00 UTC 24 March. The IAEA is seeking further information on the latest status of all Units and spent nuclear fuel at Fukushima Daiichi NPP.

Fukushima Nuclear Accident Update (25 March 2011, 05.15 UTC)

Update on Conditions of Fukushima Daiichi Nuclear Power Plant

At Unit 1 workers have advanced the restoration of off-site electricity and lighting in the Unit's main control room was recovered as of 24 March, 11:30 UTC. They are now checking the availability of the cooling system.

While the pressure in the reactor vessel remains high, Japanese authorities are reporting that it has stabilized.

At Unit 2 engineers are working for the recovery of lighting in the main control room, and the instrumentation and cooling systems.

At Unit 3, around 120 tonnes of seawater was injected in the spent fuel pool via the cooling and purification line. The operation was carried out between 23 March, 20:35 UTC and 24 March, 07:05 UTC.

Work was under way for the recovery of the instruments and cooling systems. However, it had to be suspended because three workers were exposed to elevated levels of radiation on 24 March.

At Unit 4, the spent fuel pool was sprayed with around 150 tonnes of water using concrete pump truck. The operation was carried out between 24 March, 05:36 UTC and 06:30 UTC of the same day.

At Units 5 and 6, repair of the temporary pump for Residual Heat Removal (RHR) was completed as of 24 March, 07:14 UTC, and cooling started again 21 minutes later.

At the Common Spent Fuel, the power supply was restored as of 24 March, 06:37 UTC and cooling started again 28 minutes later. Work is now under way for the recovery of the lighting and instrumentation systems.

As of 24 March, 09:40 UTC, the water temperature of the pool was around 73 °C.

As of 24 March, 10:30 UTC workers continue to inject seawater into the reactor pressure vessels of Units 1, 2 and 3 and are preparing to inject pure water.

Fukushima Nuclear Accident Update (25 March 2011, 02.50 UTC)

As previously reported, three workers at the Fukushima Daiichi nuclear power plant were exposed on 24 March to elevated levels of radiation. The IAEA has received additional information on the incident from the Japanese authorities.

The three were contracted workers laying cables in the turbine building of the Unit 3 reactor. Two of them were found to have radioactivity on their feet and legs.

These were washed in the attempt to remove radioactivity, but since there was a possibility of Beta-ray burning of the skin, the two were taken to the Fukushima University Hospital for examination and then transferred to Japan's National Institute of Radiological Sciences for further examination. They are expected to be monitored for around four days.

It is thought that the workers ignored their dosimeters' alarm believing it to be to be false and continued working with their feet in contaminated water.

The Nuclear and Industrial Safety Agency (NISA) of Japan instructed TEPCO to review the radiation control system immediately in order to avoid similar incidents in the future.

As of 24 March, 19:30 Japan time, the number of workers at the Fukushima Daiichi nuclear power plant found to have received more than 100 millisieverts of radiation dose totalled 17 including the three contract workers. The remaining fourteen are TEPCO's employees.

IAEA Briefing on Fukushima Nuclear Accident (24 March 2011, 21.30 UTC)

On Thursday, 24 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, provided the following information on the current status of nuclear safety in Japan.

Current Situation

As far as the reactors at the Fukushima Daiichi site are concerned, there is some good news to report from the last 24 hours, although the overall situation is still very serious.

With AC power connected, instrumentation continues to be recovered in Units 1, 2 and 4. Workers returned after being evacuated from Units 3 and 4 on March 23, following confirmation that black smoke emissions from Unit 3 had ceased.

Reactor pressure is increasing in Unit 1, pressure readings are unreliable in Unit 2, and stable in Unit 3 as water continues to be injected through their feed-water pipes. The temperature at the feed-water nozzle of the Reactor Pressure Vessel (RPV) is decreasing at Units 1 (243 °C) and 3 (about 185 °C), and stable at Unit 2 (about 102 °C).

Units 5 and 6 are still under cold shutdown, they are undergoing maintenance using off-site AC power and existing plant equipment.

Dose rates in the containment vessels and suppression chambers of Units 1 and 2 have decreased slightly.

Radiation Monitoring

The IAEA radiation monitoring team made additional measurements at distances from 21 to 73 km from the Fukushima nuclear power plant. At distances between 34 and 73 km, in a westerly direction from the site, the dose rate ranged from 0.6 to 6.9 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.04 to 0.4 Megabecquerel per square metre.

At distances between 30 and 32 kilometers from the Fukushima Nuclear Power Plant, in a north westerly direction from the site, dose rates between 16 and 59 microsievert per hour were measured. At these locations, the results of beta-gamma contamination measurements ranged from 3.8 to 4.9 Megabecquerel per square metre. At a location of 21 km from the Fukushima site, where a dose rate of 115 microsieverts per hour was measured, the beta-gamma contamination level could not be determined.

The second IAEA monitoring team has started their work today in Fukushima and Tokyo. Measurements will be taken to determine more precisely the actual radionuclides that have been deposited.

On-site monitoring by the Japanese authorities at the Daiichi nuclear power plant produced new data on 23 March for radionuclide concentrations in the air from samples collected between 19 and 23 March. Of the six radionuclides monitored, only iodine-131 was found to be in excess of the limits set by Japan. Overall, the dose rates reported on the site have decreased from 1930 to 210 microsievert per hour between 21 to 23 March.

There continues to be considerable daily variation in the deposition of iodine-131 and caesium-137 reported in 10 Prefectures. Recent rainfall and the resulting wet deposition may help explain the increased deposition in Tokyo. As measured by the Japanese authorities for the Shinjuku district of Tokyo, iodine-131 deposition increased by 36 000 Becquerel per square metre from 22 to 23 March, and caesium-137 deposition by 340 Becquerel per square metre.

Monitoring of the marine environment by ships of the Japanese Ministry of Education, Culture, Sport, Science and Technology has now begun. Seawater and air samples were collected on 23 March in coastal waters, at distances of about 30 km off-shore. Dose rate measurements were also taken. Results from 24 March indicate surface seawater concentrations at eight locations ranging from 24.9 to 76.8 Becquerel per litre for iodine-131, and 11.2 to 24.1 Becquerel per litre for caesium-137. Radionuclide concentrations in dust in the air above the sea were also measured. The results are being assessed by experts from the IAEA's Marine Environment Laboratory.

New data provided by the Japanese authorities has been made available concerning radionuclide concentrations in foodstuffs, milk and drinking water. Sampling has been most thorough and extensive in the Fukushima and Ibaraki Prefectures. Of the 11 varieties of vegetables sampled from 18 to 22 March iodine-131 and caesium-137 levels exceed limits set for food and drink ingestion. Permissible levels of iodine-131 and caesium-137 (one sample) were also exceeded in nearly all of the milk samples taken in Fukushima and Ibaraki Prefectures between 16 to 21 March. In addition, permissible levels of iodine-131 were exceeded in drinking water samples taken in the Fukushima and Ibaraki Prefectures and in Tokyo from 17 to 23 March. Further sampling and analysis will be carried out in the days ahead by the Japanese authorities. A joint FAO/IAEA mission to Japan will be undertaken to provide advice and assistance on sampling strategies, analysis and the interpretation of data collected by the Japanese authorities related to food contamination.

In summary, radioactivity in the environment, foodstuffs and water is moving more to the forefront, as some technical concerns related to the status of the reactors at the Fukushima Daiichi site appear to be slightly less acute in some respects. However, the overall situation on the Fukishima site remains very serious.

→ View Summary Table of Reactor Status

Fukushima Nuclear Accident Update (24 March 2011, 17:30 UTC)

Japanese Seawater Samples Show Signs of Radioactive Materials

Japanese authorities today provided the IAEA with data on seawater samples they collected on 22 and 23 March, after detecting iodine and cesium in the water near the Fukushima Daiichi nuclear power plant. (See earlier update.)

A vessel from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) collected water samples at several points 30 kilometres from the coastline and found measurable concentrations of iodine-131 and cesium-137. The iodine concentrations were at or above Japanese regulatory limits, and the cesium levels were well below those limits.

The IAEA's Marine Environmental Laboratory in Monaco has received the data for review.

Fukushima Nuclear Accident Update (24 March 2011, 17:25 UTC)

Japanese Workers Treated for Radiation Exposure

Japanese authorities today reported that three workers at the Fukushima Daiichi nuclear power plant were exposed to elevated levels of radiation. The three were working in the turbine building of reactor Unit 3 and have received a radiation dose in the range of 170-180 millisieverts.

Two of the workers have been hospitalized for treatment of severely contaminated feet, which may have suffered radiation burns. The workers had been working for about three hours in contact with contaminated water.

The IAEA is seeking additional information.

Fukushima Nuclear Accident Update (24 March 2011, 15:00 UTC)

The IAEA today released updated summary slides on reactor conditions at Fukushima Daiichi nuclear power plant.

→ View Table

Fukushima Nuclear Accident Update (24 March 2011, 14:00 UTC)

Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant - Updated

Spent fuel removed from a nuclear reactor is highly radioactive and generates heat. This irradiated fuel needs to be stored for one to three years in pools that cool the fuel, shield the radioactivity, and keep the fuel in the proper position to avoid fission reactions. If the cooling is lost, the water can boil and fuel rods can be exposed to the air, possibly leading to severe damage and a large release of radioactive materials.

Nuclear power plants must replace fuel every one to two years, and the Fukushima Daiichi reactors typically remove about 25 percent of the reactor's fuel - to be replaced with fresh, or unirradiated, fuel - during each refuelling outage. The spent fuel, which is hottest immediately after it is removed from the reactor, is placed in the spent fuel pool until it is cool enough to be moved to longer-term storage.

The concern about the spent fuel pools at Fukushima Daiichi is that the capability to cool the pools has been compromised. See diagram below for location of the pool in each reactor building.

Number of Fuel Assemblies in Cooling Pools at Fukushima Daiichi
(Reported 17 March by Japan's Ministry of Economy, Trade and Industry)

Here is a summary of spent fuel conditions at Fukushima Daiichi nuclear power plant, based on documents and confirmed by Japanese officials (new information in bold):

Unit 1

Unit 1 experienced an explosion on 12 March that destroyed the outer shell of the building's upper floors. No precise information has been available on the status of the spent fuel pool.

Unit 2

Precise information on the status of the spent fuel pool was unavailable in the days following the earthquake, but Japan's Nuclear and Industrial Safety Agency began to release temperature data on 20 March:

Workers conducted an operation to spray 40 tonnes of seawater to the spent fuel pool on 20 March, and they added another 18 tonnes on 22 March.

Unit 3

Unit 3 experienced an explosion on 14 March that destroyed the outer shell of the building's upper floors. The blast may have damaged the primary containment vessel and the spent fuel pool. To address these concerns, authorities began spraying water into the building, first by helicopter on 17 March and then by fire trucks and other vehicles through 22 March. Starting 23 March, seawater was injected into the spent fuel using the cooling and purification line. By midday 24 March, 4-5 tonnes of seawater had been injected through this line.

Unit 4

This reactor was shut down 30 November 2010 for routine maintenance, and all the fuel assemblies were transferred from the reactor to the spent fuel pool, before the 11 March earthquake. The heat load in this pool is therefore larger than the others.

On 14 March, the building's upper floors were severely damaged, possibly causing a reduction of cooling capability in the spent fuel pool. Emergency workers began spraying water into the building on 20 March, and have continued daily since then. On 22 March, workers began using a concrete pump truck that can deliver water more effectively, placing 150 tonnes of water on 22 March and 130 tonnes on 23 March.

Units 5 and 6

Instrumentation at these reactors began to indicate rising temperatures at their spent fuel pools starting on 14 March. Three days later, Japanese technicians successfully started an emergency diesel generator at Unit 6, which they used to provide power to basic cooling and fresh-water replenishment systems. Workers created holes in the rooftops of both buildings to prevent any hydrogen accumulation, which is suspected of causing earlier explosions at Units 1 and 3.

A second diesel generator came online on 18 March, and the next day, the higher-capability Residual Heat Removal (RHR) system recovered full function. External power was restored to Units 5 and 6 on 22 March. Temperatures in the spent fuel pools of Units 5 and 6 have gradually returned to significantly lower temperatures, although the Unit 5 pool temperature increased somewhat on 23 March after pumps for the RHR system were stopped when the diesel generators were removed from service.

Common Use Spent Fuel Pool

In addition to pools in each of the plant's reactor buildings, there is another facility - the Common Use Spent Fuel Pool - where spent fuel is stored after cooling at least 18 months in the reactor buildings. This fuel is much cooler than the assemblies stored in the reactor buildings. Japanese authorities confirmed as of 18 March that fuel assemblies there were fully covered by water, and the temperature was 57 °C as of 20 March, 00:00 UTC. Workers sprayed water over the pool on 21 March for nearly five hours, and the temperature on 23 March was reported to be 57 °C.

Fukushima Daiichi Nuclear Accident Update (23 March, 20:00 UTC)

Brief update on state of Fukushima Daiichi reactors

Japanese authorities today announced a number of developments at Fukushima Daiichi nuclear power plant, where reactor cooling systems were disabled following the massive earthquake and tsunami on 11 March.

At Units 1, 2, 3, and 4, workers have advanced the restoration of off-site electricity, and the lights are working in Unit 3's main control room.

Black smoke was seen emerging from the Unit 3 reactor building, spurring the temporary evacuation of workers from Units 3 and 4. The emission of smoke has now decreased significantly.

Crews continued today to use a concrete pump truck to deliver high volumes of water into the Unit 4 spent fuel pool, where there are concerns of inadequate water coverage over the fuel assemblies.

At Units 5 and 6, workers have successfully restored off-site power to the reactor, which had previously reached a safe, cold shutdown status.

(IAEA - stuff report)