Fukushima Nuclear Accident Update Log

IAEA Briefing on Fukushima Nuclear Accident (21 April 2011, 16:25 UTC)

Presentation:
Summary of Reactor Status

(Note: Unless there are significant developments, no further written brief will be issued until Tuesday 26 April.)

On Thursday, 21 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

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

At a press conference held at 11:00 (Japan local time) on 21 April, the chief cabinet secretary, Mr. Edano, announced the establishment of a no entry zone around Fukushima Daiichi nuclear power plant, as well as basic policies concerning temporary re-entry. As of midnight (Japan local time) on 22 April 2011, the area within 20 km of Fukushima Daiichi nuclear power plant is announced as a no entry zone.

Chief cabinet secretary, Mr. Edano, also announced a re-designation of the evacuation zone around Fukushima Daini nuclear power plant. He announced that "the size of the evacuation zone around the station would be reduced from 10 km to 8 km," and that "the order to evacuate based on the incident at Fukushima Daini nuclear power station would be lifted from areas farther than 8 km around the station."

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from a variety of official Japanese sources through the Japanese national competent authority, the Nuclear and Industrial Safety Agency. Additional detail is provided in the IAEA Incident and Emergency Centre (IEC) status summary with information received by 07:00 UTC on 21 April 2011.

Management of On-site Contaminated Water

Injection of approximately 17 000 L of coagulant (liquid glass) to the power cable trench of Unit 2 was carried out on 18 April and injection of approximately 7 000 L of liquid glass on 19 April. The transfer of stagnant water from the Unit 2 turbine building to radioactive waste treatment facilities commenced on 19 April.

The stagnant water (around 100 m3) in the basement of the turbine building of Unit 6 was transferred to the condenser on 19 April.

Plant status

Work to strengthen the electrical power system between Units 1 - 2 and Units 3 - 4 by establishing multiple power lines was completed on 19 April.

White "smoke" continues to be emitted from Units 2, 3 and 4..

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power.

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

In Unit 4 40 tonnes of fresh water was sprayed over the spent fuel pool on 19 April using a concrete pump truck.

Nitrogen gas is being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion in the containment vessel. The pressure in the containment vessel has stabilized. The pressure in the reactor pressure vessel is increasing.

The reactor pressure vessel temperatures in Unit 1 remain above cold shutdown conditions. The indicated temperature at the feedwater nozzle of the reactor pressure vessel is 154 °C and at the bottom of reactor pressure vessel is 113 °C.

The reactor pressure vessel temperatures in Unit 2 remain above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 135 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure. Fresh water injection (approximately 47 tonnes) to the spent fuel pool via the spent fuel pool cooling line was carried out on 19 April.

The temperature at the bottom of the reactor pressure vessel in Unit 3 remains above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 100 °C and at the bottom of the reactor pressure vessel is 108 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

There has been no change in the status in Unit 6 or in the common spent fuel storage facility.

2. Radiation Monitoring

On 20 April, deposition of I-131 was detected in 8 prefectures, ranging from 2.4 to 80 Bq/m2. Deposition of Cs-137 was detected in seven prefectures, the values reported ranging from 2.6 to 87 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. For Fukushima on 20 April a gamma dose rate of 1.9 µSv/h was reported, and for Ibaraki prefecture a gamma dose rate of 0.12 µSv/h was reported. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h.

Dose rates are also reported specifically for the eastern part of Fukushima prefecture, for distances beyond 30 km from Fukushima Daiichi. On 19 April the values in this area ranged from 0.1 to 22 µSv/h.

In cooperation with local universities, the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) has set up an additional monitoring programme. For 20 April, measurements of gamma dose rates were reported for 54 cities in 40 prefectures. In Fukushima City a value of 0.42 µSv/h was reported. For nine cities, gamma dose rates between 0.13 and 0.17 µSv/h were reported. For all other cities reported gamma dose rates were below 0.1 µSv/h.

I-131 or Cs-137 is detectable in drinking water, but at levels below 1 Bq/L and in only a few prefectures. As of 20 April, one restriction on drinking water for infants relating to I-131 (100 Bq/L) remains in place for a small scale water supply in a village of the Fukushima prefecture.

Food monitoring data reported by the Japanese Ministry of Health, Labour and Welfare on 20 April covered a total of 103 samples. These samples were taken on 3, 14, 15, 18, 19 and 20 April from nine prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Niigata, Tochigi, Tokyo and Yamagata).

Analytical results for 99 samples of various vegetables, shiitake mushrooms, fruit (strawberries), fish, seafood and unprocessed raw milk indicated that I-131, Cs-134 and Cs-137 were either not detected or had levels below the regulation values set by the Japanese authorities. Four samples of leafy vegetables (Japanese parsley, komatsuna, shinobuhuyuna and spinach) taken on 18 April from Fukushima prefecture had levels above the regulation values set by the Japanese authorities for radioactive caesium.

On 20 April, restrictions were placed on the distribution and consumption of the young of a specific sea fish (sand lance) from the coastal region of Fukushima prefecture. As has been reported previously, sand lance is the only seafood that has been found with I-131, Cs-134 or Cs-137 levels above the regulation values set by the Japanese authorities.

3. Marine Monitoring

TEPCO Seawater Monitoring Programme

TEPCO is conducting a programme for seawater monitoring (by surface sampling) at a number of near-shore and off-shore monitoring locations. Following a directive from NISA, on 16 April TEPCO announced that it will increase the number of sea sampling points from ten to 16. A further four points are to be added at 3 km from the coast and two points are to be added at 8 km from the coast. The new sampling sites are indicated on Map 1: TEPCO Seawater Sampling Locations, on which new points are indicated with green bullets.

On some days, two samples were collected at the same sampling point, a few hours apart, and analysed separately.

Until 3 April a generally decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water from the plant on 4 April, a temporary increase in radioactivity in sea water was reported. Since 5 April a general downward trend in the concentration of radionuclides in sea water for all TEPCO sampling points has been observed.

On 21 April new data for TEPCO sampling points were reported. For TEPCO 1 - 4 (sampling date 19 April) the values for both I-131 and Cs-137 were below 0.5 kBq/L. For TEPCO 5 - 10 (sampling date 18 April) the values for both I-131 and Cs-137 were below 0.3 kBq/L.

For the six new stations at 3 km off-shore and 8 km off-shore (green bullets in Map 1; sampling date 18 April), I-131 and Cs-137 were not detectable at the two stations 3 km off-shore; for all the other stations the level of I-131 was below 0.3 kBq/L and that of Cs-137 was below 0.4 kBq/L.

Map 1: TEPCO Seawater Sampling Locations:

MEXT Off-shore Seawater Monitoring Programme

On 21 April new data were reported (sampling date 19 April)for the MEXT 2, 4, 6, 8, 10 and B off-shore seawater sampling locations shown in Map 2: MEXT Seawater Sampling Locations. I-131 was detected only at the location MEXT 6 and the level was below 20Bq/L. Cs-137 was detected at locations MEXT 6 and 8 at a level of below 30 Bq/L.

Map 2: MEXT Seawater Sampling Locations:

4. IAEA Activities

Georgia and Iceland have also provided monitoring data, in addition to the States that have been mentioned in previous briefs.

On 18 April the IAEA monitoring team finished its radiological monitoring campaign and the team returned to Vienna on 20 April.

Presentation:
Summary of Reactor Status

On Wednesday, 20 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

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

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from a variety of official Japanese sources through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA). Additional detail is provided in the IEC status summary with information received by 07:00 UTC on 20 April 2011.

Management of On-Site Contaminated Water

TEPCO has provided a plan to NISA for the transfer of highly contaminated water from the basement of the turbine building of Unit 2 to the main building of the radioactive waste treatment facilities, to reduce the risk of this stagnant waste water being discharged to the environment. Measures to ensure that the radioactive waste treatment facility is watertight were completed on 18 April and the transfer of water from Unit 2 was commenced on 19 April.

Plant Status

Work to strengthen the electrical power system between Units 1 - 2 and Units 3 - 4 was completed on 19 April. White "smoke" continues to be emitted from Units 2, 3 and 4.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using a temporary electric pump with off-site power. In Unit 4 fresh water continues to be sprayed onto the spent fuel pool using a concrete pump truck.

Nitrogen gas is being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in the containment vessel has stabilized. The pressure in the reactor pressure vessel is increasing.

The reactor pressure vessel temperatures in Unit 1 remain above cold shutdown conditions. The indicated temperature at the feedwater nozzle of the reactor pressure vessel is 164 °C and that at the bottom of reactor pressure vessel is 114 °C.

The reactor pressure vessel temperatures in Unit 2 remain above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 133 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

The temperature at the bottom of the reactor pressure vessel in Unit 3 remains above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 99 °C and that at the bottom of reactor pressure vessel is 110 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

There has been no change in the status in Units 5 and 6 or in the common spent fuel storage facility.

2. Radiation Monitoring

On 19 April, deposition of I-131 was detected in 13 prefectures, ranging from 1.8 to 368 Bq/m2. Deposition of Cs-137 was detected in seven prefectures, the values reported ranging from 2.4 to 160 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. For Fukushima on 20 April a gamma dose rate of 1.9 µSv/h was reported, and for Ibaraki prefecture a gamma dose rate of 0.13 µSv/h was reported. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h.

In cooperation with local universities, the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) has set up an additional monitoring programme. For 19 April, measurements of the gamma dose rates were reported for 53 cities in 40 prefectures. In Fukushima City a value of 0.42 µSv/h was reported. For all other cities reported gamma dose rates were below 0.13 µSv/h.

In drinking water, I-131 or Cs-137 is detectable, but at levels below 1 Bq/L and in only a few prefectures. As of 17 April, one restriction on drinking water for infants relating to I-131 (100 Bq/L) is in place in a small scale water supply in a village of the Fukushima prefecture.

Food monitoring data reported by the Japanese Ministry of Health, Labour and Welfare on 19 April covered a total of 36 samples. These were taken on 4, 18 and 19 April from eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Nagano, Niigata and Saitama). Analytical results for 35 of the samples of various vegetables, shiitake mushrooms, fruit (strawberries), edible shoots (Japanese Angelica tree), seafood, yoghurt and unprocessed raw milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. One sample of seafood (sand lance) taken on 18 April from the coastal region of Fukushima had levels above the regulation values set by the Japanese authorities for I-131 and also for radioactive caesium.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater monitoring (by surface sampling) at a number of near-shore and off-shore monitoring locations. Following a directive from NISA, on 16 April TEPCO announced that it will increase the number of sea sampling points from ten to 16. A further four points are to be added at 3 km from the coast and two points are to be added at 8 km from the coast. The new sampling sites are indicated on Map 1: TEPCO Seawater Sampling Locations, on which new points are indicated with green bullets.

On some days, two samples were collected at the same sampling point, a few hours apart, and analysed separately.

Until 3 April a generally decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water from the plant on 4 April, a temporary increase in radioactivity in seawater was reported. Since 5 April a general downward trend in the concentration of radionuclides in seawater for all TEPCO sampling points has been observed.

On 20 April no new data for TEPCO 1 - 4 sampling points were reported. For TEPCO 5 - 10, data for TEPCO 8 only were reported on 20 April (for sampling on 17 April). Both I-131 and Cs-137 were below 0.1 kBq/L.

Map 1: TEPCO Seawater Sampling Locations:

MEXT Off-shore Monitoring Programme

On 20 April no new data were reported for the MEXT off-shore sampling locations shown on Map 2: MEXT Seawater sampling Locations.

Map 2: MEXT Seawater Sampling Locations:

4. IAEA Activities

Sri Lanka has also provided monitoring data, in addition to the countries that have been mentioned in previous briefs.

On 18 April the IAEA monitoring team finished its radiological monitoring campaign and the team is to return to Vienna on 20 April.

Presentations:
Summary of Reactor Status
Fukushima Radiological Monitoring and Consequences
Fukushima Marine Environment Monitoring
Watch Video

On Tuesday, 19 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

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

On 17 April, the Ministry of Economy, Trade and Industry (METI) announced that TEPCO had issued a "Roadmap towards Restoration from the Accident at the Fukushima Daiichi Nuclear Power Station". The roadmap outlines 63 measures to be taken in two steps over a period of six to nine months.

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from a variety of official Japanese sources through the nation's national competent authority, the Nuclear and Industrial Safety Agency. Additional detail is provided in the IEC status summary with information received by 07:00 UTC on 19 April 2011.

TEPCO has provided a plan to NISA for the transfer of highly contaminated water from the basement floor of the turbine building of Unit 2 to the Main Building of the Radioactive Waste Treatment Facilities in order to reduce the risk of this stagnant waste water being discharged to the environment.

On 17 and 18 April, an unmanned robot was used to conduct inspections of the Reactor Buildings in Units 1, 2 and 3.

As of 18 April, white "smoke" was still observed coming from Units 2, 3 and 4.

In Unit 1, fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3, fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

RPV temperatures remain above cold shutdown conditions in all Units. In Unit 1 the temperature at the feed water nozzle of the RPV is 170 °C and at the bottom of the RPV is 115 °C. In Unit 2, the temperature at the feed water nozzle of the RPV is 142 °C. In Unit 3 the temperature at the feed water nozzle of the RPV is 100 °C and at the bottom of the RPV is 114 °C.

In Unit 1 Nitrogen gas is being injected into the containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel has stabilised. The pressure in the RPV is increasing. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

On 18 April the concrete pump truck sprayed water into the Unit 3 spent fuel pool. On 17 April, approximately 140 tonnes of fresh water was pumped into the Unit 4 spent fuel pool.

There has been no change in the status in Units 5 and 6 or in Common Spent Fuel Storage Facility.

On 17 and 18 April, anti-scattering agent was sprayed over an additional 3100 m2 area near the Centralized Waste Treatment Facility.

2. Radiation Monitoring

On 18 April, deposition of I-131 was detected in 6 prefectures ranging from 2.3 to 65 Bq/m2. Deposition of Cs-137 was detected in 2 prefectures; the values reported were 4.7 and 14.8 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. The values tend to decrease over time. For Fukushima, on 18 April a dose rate of 1.9 µSv/h was reported. In the Ibaraki prefecture, a gamma dose rate of 0.13 µSv/h was reported; in all other prefectures, reported gamma dose rates were below 0.1 µSv/h.

Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances beyond 30 km from Fukushima-Daiichi. On 17 April, the values in this area ranged from 0.1 to 23 µSv/h.

MEXT has set up an additional monitoring programme in cooperation with local universities. For 18 April, measurements of the gamma dose rates were reported for 53 cities in 40 prefectures. In Fukushima City, a value of 0.38 µSv/h was observed; in 9 cities, gamma dose rates ranged from 0.13 to 0.17 µSv/h. For the other cities, gamma dose rates of less than 0.1 µSv/h were reported.

In drinking water, I-131 or Cs-137 is detectable at very low levels only in a few prefectures. As of 17 April, one restriction for infants related to I-131 (100 Bq/l) is in place in a small scale water supply in a village of the Fukushima prefecture.

On 18 April, the IAEA Team made measurements at 12 different locations in the Fukushima area at distances ranging from 13 to 43 km, South and Southwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.25 to 6.8 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.01 to 0.15 Megabecquerel/m2.

Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 18 April, and covered a total of 23 samples taken on 8, 15, 17 and 18 April. Analytical results for all of the samples of various vegetables, shiitake mushrooms, leafy vegetables, fruit (strawberries), fish and unprocessed raw milk in eight prefectures (Chiba, Fukushima, Gunma, Hokkaido, Ibaraki, 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.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations following a directive from NISA, on 16 April TEPCO announced they will increase the number of sea sampling points from 10 to 16. A further four points will be added at 3 km from the coast and two points will be added at 8 km from the coast. The new sampling sites are indicated on the map below. (See Map 1: TEPCO Seawater Sampling Locations, new points indicated with green bullets).

On some days, two samples were collected at the same sampling point, a few hours apart and analysed separately.

Until 3 April a general decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase in radioactivity has been reported. Again since 5 April, general decreasing trend has been observed in the concentration of radionuclides in sea water for all TEPCO sampling points.

On 18 April new data for TEPCO sampling points have been reported (sampling date 15 April). Since 9 April the levels of I-131 and Cs-137 at the sampling points TEPCO number 5-10 are lower than those at the near-shore stations (below 0.5 kBq/l) and the levels of I-131 and Cs-137 at the sampling points TEPCO 1 - 4 are below 20 kBq/l. At all TEPCO sampling points since 9 April a decreasing trend has been observed.

MEXT Off-shore Monitoring Programme

The Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) initiated the off-shore monitoring program on 23 March and subsequently 4 points were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B. (See Map 2: MEXT Seawater sampling Locations).

The results reported on 18 April (sampling date 15 April) showed that Cs-137 and I-131 were detected at MEXT 4, 6 and 8. The highest concentrations were recorded at MEXT 4 (below 200Bq/l for Cs-137 and about 160 Bq/l for I-131). At MEXT 6 and 8 sampling locations both Cs-137 and I-131 were reported at levels below about 40 Bq/l.

The results reported on 19 April (sampling date 17 April) showed that at the stations MEXT 5, 7 and 9, Cs-137 and I-131 are below 90 Bq/l.

Neither Cs-137 nor I-131 have been detected at MEXT A and B. (See Map 2 from MEXT).

Map 1: TEPCO Seawater Sampling Locations:

Map 2: MEXT Seawater Sampling Locations:

4. IAEA Activities

The mission of BWR expert to Japan provided the IAEA with a unique opportunity to communicate directly with the various stakeholders working to address challenges at both the Daiichi and Daini reactor sites. All organizations fully cooperated with the IAEA team and provided the team with a better understanding of event sequences, current challenges and future plans and priorities.

The IAEA team of BWR experts toured the Fukushima Daiichi site and the Emergency center. The team was also able to tour the Fukushima Daini site. At all facilities, the IAEA team noted a strong, positive attitude broadly displayed by the management, support and task implementation teams, even though the situation is not yet stabilized. Activities appeared to be well organized, efforts were thoroughly planned, and responsibilities well communicated.

Presentation:
Summary of Reactor Status

On Monday, 18 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

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

On 17 April, the Ministry of Economy, Trade and Industry (METI) announced that TEPCO had issued a "Roadmap towards Restoration from the Accident at the Fukushima Daiichi Nuclear Power Station." The roadmap outlines 63 measures to be taken in two steps over a period of six to nine months. TEPCO declared they will "make every effort to enable evacuees to return to their homes and for all citizens to be able to secure a sound life."

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information updates from a variety of official Japanese sources, through the national competent authorities: the Nuclear and Industrial Safety Agency (NISA) and the Ministry of Education, Culture, Sports, Science and Technology (MEXT).

Based on the information received by 18 April 2011, 02:00 UTC the following update related to the reactor units at the Fukushima Daiichi Nuclear Power Plant and related environmental conditions is provided.

As a countermeasure against a possible tsunami, the distribution boards for the pumps injecting water to the reactor pressure vessels of Units 1, 2 and 3 were transferred to higher ground on 15 April. In order to minimize the liberation of radioactive material into the ocean, two sandbags filled with Zeolite were placed between the Inlet Screen Pump Room of Unit 1 and Unit 2. Further, five sandbags filled with Zeolite were placed between the Inlet Screen Pump Room of Unit 2 and Unit 3 on 17 April. The Zeolite material is designed to capture specific radioactive elements. It is intended to sample and analyze the Zeolite material periodically to determine the effectiveness of this procedure.

The removal of debris (amount equivalent to 8 containers) using remote-control heavy machinery continued on 16 April.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel has stabilised. The pressure in the RPV is stable.

In Unit 1, fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3, fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 the temperature at the feed water nozzle of the RPV is 180 °C and at the bottom of the RPV is 117 °C. In Unit 2, the temperature at the feed water nozzle of the RPV is 141 °C. In Unit 3 the temperature at the feed water nozzle of the RPV is 91 °C and at the bottom of the RPV is 122 °C.

In accordance with the report of the Nuclear Emergency Response HQs (Prime Minister's Office) from 15 April, thermography temperatures of the Containment Vessel and Spent Fuel Pool in Unit 1 were 33 & deg;C and 36 °C respectively. In Unit 3 the temperatures were 68 °C and 59 °C at the same positions. Also on 15 April, thermography temperature of the Unit 2 reactor building roof was 31 °C

As of 16 April, no white "smoke" was seen to be coming from Unit 1 although white "smoke" was still observed coming from Units 2 and 3. As of 16 April white "smoke" was also visible in Unit 4.

Fresh water injection (around 45 tonnes) to the spent fuel pool was carried out via the spent fuel pool cooling line of Unit 2 and completed by 16 April. Due to the occurrence of an earthquake on 16 April, the motor-driven pump was stopped. The spent fuel pool was confirmed to be filled with water.

In accordance with NISA Release 94, TEPCO took water samples from the spent fuel pool of Unit 4 on 12 April, in order to examine the conditions. The sample was taken by using the arm of the concrete pump vehicle. At the same time, the temperature of water in the spent fuel pool of Unit 4 was measured with a thermistor attached to the arm of the concrete pump vehicle. The activities for I-131, Cs-134 and Cs-137 were 220 Bq/cm3, 88 Bq/cm3 and 93 Bq/cm3 respectively.

There has been no change in the status in Units 5 and 6.

The power supply to the Common Spent Fuel Pool was temporarily interrupted due to a short-circuit on 17 April.

2. Radiation Monitoring

From 15 to 17 April, I-131 was detected in only one prefecture on 15 April; with a reported value of 4.1 Bq/m2. During this period, deposition of Cs-137 was detected in 8 prefectures. The total deposition of Cs-137 in these prefectures on these 3 days ranged from 2.3 Bq/m2 to 66 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. The values tend to decrease over time. For Fukushima, on 18 April a dose rate of 1.9 µSv/h was reported. In the Ibaraki prefecture, a gamma dose rate of 0.13 µSv/h was reported; in all other prefectures, reported gamma dose rates were below 0.1 µSv/h.

Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances beyond 30 km from Fukushima-Daiichi. On 16 April, the values in this area ranged from 0.1 to 25 µSv/h.

In cooperation with local universities, MEXT has set up an additional monitoring programme, for 17 April, measurements of the gamma dose rates were reported for 53 cities in 40 prefectures. In 43 cities, the gamma dose rates were below 0.1 µSv/h. In 9 cities, gamma dose rates ranged from 0.12 to 0.17 µSv/h. In Fukushima City, a value of 0.42 µSv/h was observed.

Only in a few prefectures, I-131 or Cs-137 is detectable in drinking water at very low levels. As of 16 April, one restriction for infants related to I-131 (100 Bq/l) is in place in a small scale water supply in a village of the Fukushima prefecture.

On 15 and 16 April, the IAEA Team made measurements at 44 different locations in the Fukushima area at distances ranging from 20 to 58 km, West from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.6 to 37 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.03 to 2.8 Megabecquerel/m2. The highest values were observed at distances of less than 30 km from the power plant.

On 17 April, the IAEA Team made measurements at 17 different locations in the Fukushima area at distances ranging from 20 to 62 km, North and Northwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.4 to 3.3 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.03 to 0.27 Megabecquerel/m2.

Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 15 April (34 samples), 16 April (65 samples) and 17 April (51 samples). These reported analytical results covered a total of 150 samples taken from 13 to 16 April. Analytical results for 146 of the 150 samples for various vegetables, spinach and other leafy vegetables, shitake mushrooms, fruit (strawberries), seafood and unprocessed raw milk in nine prefectures (Chiba, 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. In Fukushima prefecture, three samples of shitake mushrooms taken on 14 April were above the regulation value set by the Japanese authorities for Cs-134 and Cs-137. One sample of shitake mushrooms taken on 14 April was above the regulation values set by the Japanese authorities for I-131 and/or Cs-134 and Cs-137.

On 16 April, the restriction on the distribution of raw unprocessed milk produced in Fukushima was lifted in 25 areas (Fukushima city, Nihonmatsu city, Date city, Motomiya city, Kunimi town, Otama village, Furudono city, Koriyama city, Sukagawa city, Tamura city (excluding former Toji village area), Miharu town, Ono town, Kagamiishi town, Ishikawa town, Asakawa town, Hirata village, Shirakawa city, Yabuki town, Izumisaki village, Nakajima village, Saigo village, Samekawa village, Hanawa town, Yamatsuri town and Iwaki city).

On 17 April, the restriction on the distribution of Kakina and parsley produced throughout Ibaraki prefecture was lifted. The restriction on the distribution of spinach from Ibaraki prefecture was also lifted with the exception of spinach produced in the cities of Kitaibaraki and Takahagi.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations. Following a directive from NISA, on 16 April TEPCO announced they will increase the number of sea sampling points from 10 to 16. A further four points will be added at 3 km from the coast and two points will be added at 8 km from the coast.

On some days, two samples were collected at the same sampling point, a few hours apart and analysed separately.

Until 3 April a general decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase in radioactivity has been reported. Again since 5 April, general downward in the concentration of radionuclides in sea water for all TEPCO sampling points has been observed.

On the 18 April no new data for TEPCO sampling points have been reported.

MEXT Off-shore Monitoring Programme

The Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B. (See Map 2: MEXT Seawater sampling Locations).

The last results reported on 18 April (sampling date 15 April) showed that Cs-137 and I-131 were detected at MEXT 4, 6 and 8. The highest concentrations were recorded at MEXT 4 (below 200Bq/l for Cs-137 and about 160 Bq/l for I-131). At MEXT 6 and 8 sampling locations both C-s-137 and I-131 were reported at levels below about 40 Bq/l.

Map 2: MEXT Seawater Sampling Locations

Presentation:
Summary of Reactor Status

(Note: The next written brief will be available on Monday, 18 April, unless there are any significant developments.)

On Friday, 15 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

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

Changes to Fukushima Daiichi Plant Status

The transfer of contaminated water from the trench of the Unit 2 Turbine Building to the condenser started on 12 April and continued on 13 April until approximately 660 tonnes were transferred.

To minimize the movement of contaminated water to the open sea, temporary boards to stop water (3 steel plates in total) were installed on 13 April on the ocean-side of the Inlet Bar Screen of Unit 2.

Silt fences have also been installed in the inlet canal and in front of the Inlet Bar Screens of Units 1, 2, 3 and 4. On 11 April, a silt screen was installed at the southern end of the inlet canal. The installation in front of the Inlet Bar Screen of Units 3 and 4 was completed on 13 April and for Units 1 and 2 on 14 April.

As of 14 April, white "smoke" was still observed coming from Units 2 and 3. White "smoke" was also observed coming from Unit 4 on 14 April.

On 13 April, Japan's Nuclear and Industrial Safety Agency (NISA) reported that the Tokyo Electric Power Compan (TEPCO) had begun to install a backup line for providing fresh water to the Reactor Pressure Vessels (RPVs) at Units 1, 2, and 3.

In Unit 1, fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3, fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel has stabilised. The pressure in the RPV is increasing as indicated on one channel of instrumentation. The other channel shows RPV pressure as stable. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1, the temperature at the feed water nozzle of the RPV is 197 °C and at the bottom of the RPV is 119 °C. In Unit 2, the temperature at the feed water nozzle of the RPV is 150 °C. In Unit 3 the temperature at the feed water nozzle of the RPV is 91 °C and at the bottom of the RPV is 121 °C.

On 14 April, a concrete pump truck, with a capacity of 50t/h, began spraying fresh water to the Unit 3 spent fuel pool. In Unit 4, a sample of the water in the spent fuel pool was collected for analysis.

There has been no change in status in Unit 5 and 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 14 April, depositions of both Iodine-131 and Cesium-137 were detected in 1 and 5 prefectures respectively. For both I-131 and Cs-137, the depositions detected were below 20 Bq/m2 at all stations.

Gamma dose rates are measured daily in all 47 prefectures. The values have tended to decrease over time. For Fukushima, on 14 April a dose rate of 2.0 µSv/h was reported. In the Ibaraki prefecture, a gamma dose rate of 0.14 µSv/h was reported. The gamma dose rates in all other prefectures were below 0.1 µSv/h.

Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances beyond 30 km from Fukushima Daiichi. On 14 April, the values in this area ranged from 0.1 to 21 µSv/h.

In cooperation with local universities, Japan's Ministry of Education, Culture, Sports, Science and Technology (MEXT)has set up an additional monitoring programme and measurements of the gamma dose rates are made in 54 cities in 40 prefectures. As of 14 April, the gamma dose rates were below 0.1 µSv/h in 45 cities. In 8 cities, gamma dose rates ranged from 0.13 to 0.17 µSv/h. In Fukushima City, a value of 0.42 µSv/h was observed.

Only in a few prefectures, I-131 or Cs-137 is detectable in drinking water at very low levels. As of 12 April, one restriction for infants related to I-131 (100 Bq/l) is in place in a smallscale water supply in a village of the Fukushima prefecture.

On 14 April, an IAEA Team made measurements at 11 different locations in the Fukushima area at distances ranging from 15 to 39 km, South and Southwest from the Fukushima Daiichi nuclear power plant. At these locations, the dose rates ranged from 0.3 to 2.8 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.16 to 2.5 MBq/ m2. The highest values were observed at distances of less than 23 km from the power plant.

NISA reported on 14 April that among approximately 300 workers at the Fukushima Daiichi plant, 28 have received accumulated doses exceeding 100 mSv in the period related to this emergency. No worker has received a dose above Japan's guidance value of 250 mSv for restricting the exposure of emergency workers.

Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 14 April for a total of 50 samples taken from 11th to 14 April. Analytical results for all of the samples of various vegetables, mushrooms, fruits (strawberries), various meats, seafood and unprocessed raw milk in ten prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Nagano, Niigata, Saitama, Tochigi 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.

On 14 April, the Prime Minister of Japan approved the lifting of restrictions on the distribution of kakina in Tochigi prefecture.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations. (See Map 1: TEPCO Seawater Sampling Locations).

On some days, two samples were collected at the same sampling point, a few hours apart and analysed separately.

Until 3 April a general decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase in radioactivity was reported. Since 5 April, a general downward trend in the concentration of radionuclides in sea water for all TEPCO sampling points has been observed.

On 15 April, new data for TEPCO 1 - 4 sampling points have been reported. At all four locations, the concentration of both I-131 and Cs-137 measured on 12 April was below 2kBq/l.

For TEPCO 5 - 10 no new data have been reported.

MEXT Off-shore Monitoring Programme

MEXT initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B. (See Map 2: MEXT Seawater Sampling Locations).

The most recent results reported on 11 April showed that Cs-137 was only detected at MEXT 4 (below 100Bq/l). The highest concentration of I-131 (about 90 Bq/l) was also recorded at MEXT 4. For other sampling locations I-131 was reported at levels below about 15 Bq/l.

On 15 April, no new data from any MEXT sampling points have been reported.

Map 1: TEPCO Seawater Sampling Locations:

Map 2: MEXT Seawater Sampling Locations:

4. IAEA Activities

The 141st Session of the FAO Council was briefed by representatives of the Joint FAO/IAEA Division on the nuclear emergency in Japan on Friday, 15 April, at the FAO Headquarters in Rome, Italy. The briefing included a general background summary of the emergency, the current situation in Japan, FAO/IAEA/WHO responses and actions taken to date, and future challenges. The Member States expressed their appreciation for the IAEA/FAO/WHO inter-agency collaboration and coordination during the Japanese nuclear emergency and called for strengthening cooperation in future remediation actions.

Presentation:
Summary of Reactor Status

On Thursday, 14 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

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

Earthquake of 13 April

The NISA Press Release reported that an earthquake occurred at Hamadori in Fukushima prefecture on 13 April, at 01:07 UTC. The earthquake had a moment magnitude of M 5.4 and was at a depth of 24.7 km, as reported by the IAEA International Seismic Safety Centre. The distances from the earthquake's epicenter to Fukushima Daini and Fukushima Daiichi nuclear power plant were 67 and 75 km respectively. No unusual events have been reported at the near sites (Onagawa, Fukushima Daiichi, Fukushima Daini and Tokai).

Changes to Fukushima Daiichi Plant Status

Freshwater injection is confirmed to continue for Units 1 to 3. The transfer of contaminated water from Unit 2 turbine building to the condenser was started (12 April) and suspended (13 April) to check for any leakage. Temperature at the Unit 1 outlet nozzle shows a decreasing trend continuously for several days now.

To minimize migration of contaminated water to the open sea, on the ocean-side of the Inlet Bar Screen of Unit 2, the two temporary steel plates (3 plates in total) were installed to stop water from leaking out of the inlet bay (around 08:30 untill 10:00, 13 April). In addition, a silt fence to prevent the spread of the contaminated water was installed in front of the Screen of Units 3 and 4. (13:50 UTC, 13 April).

In Unit 1 fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel has stabilised. The pressure in the RPV is increasing as indicated on one channel of instrumentation. The other channel shows RPV pressure as stable. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 the temperature at the feed water nozzle of the RPV is 206 °C and at the bottom of the RPV is 119 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 167 °C. In Unit 3 the temperature at the feed water nozzle of the RPV is 92 °C and at the bottom of the RPV i

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Last update: 12 November 2014