Complete Guide to the Three Worst Nuclear Power Plant Accidents: Fukushima 2011, Three Mile Island 1979, and Chernobyl 1986 - Authoritative Coverage of Radiation Releases and Effects
U.S. Government, Nuclear Regulatory Commission (NRC), International Atomic Energy Agency (IAEA), Environmental Protection Agency (EPA), U.S. Senate
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Copyright 2011 Progressive Management
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Chapter 1: Roadmap towards Restoration from the Accident at Fukushima Daiichi Nuclear Power Station
Chapter 2: International Atomic Energy Agency (IAEA) Statements on the Fukushima Nuclear Accident Through mid-April
Chapter 3: Japan Government Statements and Notices About the Fukushima Nuclear Crisis - including News Briefings by Nuclear and Industrial Safety Agency (NISA), Chief Cabinet Secretary Edano, and Prime Minister Kan
Chapter 4: CRS Report for Congress - Fukushima Nuclear Crisis
Chapter 5: Nuclear Regulatory Commission Material
Chapter 6: American Government Agencies
Chapter 7: Energy Department Material
Chapter 8: Testimony before the U.S. Senate
Chapter 9: Tokyo Electric Power Company (TEPCO) Press Releases Regarding the Kashiwazaki-Kariwa Nuclear Power Station after the Niigata-Chuetsu-Oki Earthquake (2007 Incident and Response)
THREE MILE ISLAND ACCIDENT
CHERNOBYL ACCIDENT
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Chapter 1: Roadmap towards Restoration from the Accident at Fukushima Daiichi Nuclear Power Station
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Press Release (Apr 17, 2011)
With regard to the accident at Fukushima Daiichi Nuclear Power Station due to the Tohoku-Chihou-Taiheiyo-Oki Earthquake occurred on Friday, March 11th, 2011, we are currently making our utmost effort to bring the situation under control. This announcement is to notify the roadmap that we have put together towards restoration from the accident.
1. Basic Policy
By bringing the reactors and spent fuel pools to a stable cooling condition and mitigating the release of radioactive materials, we will make every effort to enable evacuees to return to their homes and for all citizens to be able to secure a sound life.
2. Targets
Based on the basic policy, the following two steps are set as targets: "Radiation dose is in steady decline" as "Step 1" and "Release of radioactive materials is under control and radiation dose is being significantly held down" as "Step 2." Target achievement dates are tentatively set as follows: "Step 1" is set at around 3 months and "Step 2" is set at around 3 to 6 months after achieving Step 1.
3. Immediate Actions
Immediate actions were divided into three groups, namely, "I. Cooling", "II. Mitigation", "III. Monitoring and Decontamination."
For the following five issues—"Cooling the Reactors," "Cooling the Spent Fuel Pools," "Containment, Storage, Processing, and Reuse of Water Contaminated by Radioactive Materials (Accumulated Water)," "Mitigation of Release of Radioactive Materials to Atmosphere and from Soil," and "Measurement, Reduction and Announcement of Radiation Dose in Evacuation Order / Planned Evacuation / Emergency Evacuation Preparation Areas" — targets are set for each of the five issues and various countermeasures will be implemented simultaneously.
We would like to deeply apologize again for the grave inconvenience and anxiety that the broad public has been suffering due to the accident at the Fukushima Daiichi Nuclear Power Station. We will continue to make every endeavor to bring the situation under control.
Tokyo Electric Power Company
Roadmap towards Restoration from the Accident at Fukushima Daiichi Nuclear Power Station
1. Basic Policy
By bringing the reactors and spent fuel pools to a stable cooling condition and mitigating the release of radioactive materials, we will make every effort to enable evacuees to return to their homes and for all citizens to be able to secure a sound life.
2. Targets
Based on the basic policy, the following two steps are set as targets:
Step 1: Radiation dose is in steady decline.
Step 2: Release of radioactive materials is under control and radiation dose is being significantly held down.
(Note) Issues after Step 2 will be categorized as “Mid-term Issues”
Target achievement dates are tentatively set as follows, although there will still be various uncertainties and risks:
Step 1: around 3 months
Step 2: around 3 to 6 months (after achieving Step 1)
(Note) Announcements will be made as soon as timing of step-wise target achievement or quantitative prospects are determined, as well as if revisions to the targets or achievement dates become necessary.
3. Immediate Actions
In order to achieve the above targets, immediate actions were divided into 3 groups with targets set for each of the 5 issues. Various countermeasures will be implemented simultaneously
In order to achieve Step 1, overcoming the following two issues that are currently being addressed will be critical:
ONE. Prevention of hydrogen explosion inside the primary containment vessel (hereafter, PCV) (Units 1 to 3.)
Cooling the reactor by injecting fresh water into the reactor increases the chance of steam condensation, leading to a concern of potentially triggering a hydrogen explosion.
Nitrogen gas will be injected into the PCV of each unit to keep the concentration of hydrogen and oxygen below flammability limit.
TWO. Prevention of release of contaminated water with high radiation level outside of the site boundary (Unit 2.)
While cooling the reactor by injecting fresh water, accumulation of contaminated water with high radiation level in the turbine building is increasing (possible release to outside of the site boundary.)
Actions will be taken against accumulated water to (1) secure several storage places and (2) install facilities to process the contaminated water and reduce the radiation dose, among others.
Area I. Cooling:
Issue (1) Cooling the Reactors
Step 1 / ONE. Maintain stable cooling - Nitrogen gas injection; Flooding up to top of active fuel; Examination and implementation of heat exchange function
Step 1 / TWO (Unit 2) Cool the reactor while controlling the increase of accumulated water until the PCV is sealed
Step 2: /THREE. Achieve cold shutdown condition (sufficient cooling is achieved depending on the status of each unit.) Maintain and reinforce various countermeasures in Step 1.
Issue (2) Cooling the Spent Fuel Pools
Step 1 / FOUR. Maintain stable cooling * Enhance reliability of water injection * Restore coolant circulation system * (Unit 4) Install supporting structure
Step 2 / FIVE. Maintain more stable cooling function by keeping a certain level of water. Remote control of coolant injection operation. Examination and implementation of heat exchange function
Area II Mitigation
Issue (3) Containment, Storage, Processing, and Reuse of Water Contaminated by Radioactive Materials (Accumulated Water)
Step 1 / SIX. Secure sufficient storage place to prevent water with high radiation level from being released out of the site boundary. Installation of storage / processing facilities.
Step 1 / SEVEN. Store and process water with low radiation level * Installation of storage facilities/decontamination processing.
Step 2 / EIGHT. Decrease the total amount of contaminated water. Expansion of storage/processing facilities. Decontamination/Desalt processing (reuse), etc.
Issue (4) Mitigation of Release of Radioactive Materials to Atmosphere and from Soil
Step 1 / NINE. Prevent scattering of radioactive materials on buildings and ground - Dispersion of inhibitor * Removal of debris * Installing reactor building cover
Step 2 / TEN. Cover the entire buildings (as temporary measure).
Area III. Monitoring/ Decontamination
Issue (5) Measurement, Reduction and Announcement of Radiation Dose in Evacuation Order / Planned Evacuation / Emergency Evacuation Preparation Areas
Step 1 / ELEVEN * Expand/enhance monitoring and inform of results fast and accurately - Examination and implementation of monitoring methods.
Step 2 / TWELVE. Sufficiently reduce radiation dose in evacuation order / planned evacuation / emergency evacuation preparation areas * Decontamination/monitoring of homecoming residences.
(Note) With regard to radiation dose monitoring and reduction measures in evacuation order/planned evacuation/emergency evacuation preparation areas, we will take every measure through thorough coordination with the national government and by consultation with the prefectural and municipal governments.
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Roadmap towards Restoration from the Accident at Fukushima Daiichi Nuclear Power Station (Attachment)
Basic Policy: By bringing the reactors and spent fuel pools to a stable cooling condition and mitigating the release of radioactive materials, we will make every effort to enable evacuees to return to their homes and for all citizens to be able to secure a sound life. Note: Reactor pressure vessel is denoted as “RPV” and primary containment vessel is denoted as “PCV.”
Area I. Cooling
Issue: (1) Cooling the Reactors
Current Status as of April 16th
Current Status [1] (Units 1 to 3) Cooling achieved by water injection while there is partial damage to fuel pellets. Continued injection of fresh water and further cooling measures are required.
Countermeasure [1]: Injecting fresh water into the RPV by pumps. Risk [1]: Possibility of hydrogen explosion due to condensation of steam in the PCV when cooled, leading to increased hydrogen concentration.
Countermeasure [2]: Injecting nitrogen gas into the PCV (start from Unit 1.)
Countermeasure [3]: Consideration of flooding the PCV up to the top of active fuel.
Current Status [2] (Units 1 to 3) High likelihood of small leakage of steam containing radioactive materials through the gap of PCV caused by high temperature.
Lowering the amount of steam through cooling and implementation of leakage prevention are required.
Countermeasure [4]: Lower the amount of steam generated by sufficiently cooling the reactor (to be achieved by measures in Steps 1 and 2.)
Countermeasure [5]: Consideration of shielding the leakage by covering the reactor building (coordinate with issue [4].)
Current Status [3] (Unit 2) Large amount of water leakage, indicating high likelihood of PCV damage. Repairing the damaged location is required. Need to control the amount of water injection since leakage increases as injection increases.
Countermeasure [6]: Consideration of sealing the damaged location (e.g., filling with grout (glutinous cement)
Countermeasure [7]: Cooling at minimum water injection rate (control the leakage of contaminated water.)
Risk[2]: Possibility of prolonged work of sealing the damaged location (countermeasures [12] and [14])
Current Status [4] Secured multiple off-site power (1 system each from TEPCO and Tohoku EPCO) and deployed backup power (generator cars / emergency generators)
Risk [3]: Possibility of (partial) loss of power from the grid caused by ensuring aftershocks and lightning in summer.
Countermeasure [8]: Install interconnecting lines of offsite power soon.
(2) Cooling the Spent Fuel Pools
Current Status [5] Fresh water is injected from outside for Units 1, 3, 4 and through normal cooling line for Unit 2. Reduction of worker exposure and countermeasures for aftershocks are required.
Countermeasure [18]: Consideration/implementation of improving reliability of external water injection by concrete pumpers (Giraffe etc.) /switch to remote-controlled operation.
Current Status [6]: Confirmation of release of radioactive materials from the pool
Countermeasure [19]: Sampling and measurement of steam/pool water by Giraffe, etc. Most fuels in Unit 4 have been confirmed intact according to the result of pool water analysis.
Current Status [7]: Walls of the building supporting the pool have been damaged. Tolerance evaluation is especially needed for Unit 4.
Countermeasure [20]: Seismic tolerance assessment of Unit 4. A certain level of seismic tolerance has been confirmed.
Countermeasure [21]: Continue monitoring and examine necessary countermeasures (countermeasure [26].)
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Targets, Countermeasures and Risks
<Step 1 (around 3 months)>
Radiation dose is in steady decline.
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Target [1] (Unit 1 to 3) Maintain stable cooling.
Countermeasure [9]: Flood the PCV up to the top of active fuel.
Countermeasure [10]: Reduce the amount of radioactive materials (utilization of standby gas treatment system (filter), etc.) when PCV venting (release of steam containing radioactive materials into the atmosphere). Countermeasure [11]:Continue preventing hydrogen explosion by injecting nitrogen into the PCV.
Risk [4]: Increase in water leakage into the turbine building in the process of flooding the PCV.
Countermeasure [12]: Consideration and implementation of measures to hold down water inflow (e.g., circulating the water back into the RPV by storing and processing the accumulated water in the turbine building.) Countermeasure [13]: Consideration of recovering heat exchange function for the reactor (installing heat exchangers).
Risk [5]: Possibility of prolonged work in high dose level area (keep countermeasures [9] and [12])
Target [2] (Unit 2) Cool the reactor while controlling the increase of accumulated water until PCV is sealed.
Countermeasure [14]: Continue cooling by current minimum injection rate.
Countermeasure [15]: Continue prevention of hydrogen explosion by nitrogen injection into the PCV.
Countermeasure [16]: Continue consideration and implementation of sealing measure at damaged location. Implement cooling measures similar to those for Units 1 and 3 once the damaged location is sealed.
Risk[2]: Possibility of prolonged work of sealing the damaged location (continue countermeasures [12] and [14]）
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<Step 2 (around 3 to 6 months * after achieving step 1)>
Release of radioactive materials is under control and radiation dose is being significantly held down.
* * * * * * * * * * * *
Target [3] Achieve cold shutdown condition (sufficient cooling is achieved depending on the status of each unit.)
Countermeasure [17]: Maintain and enhance countermeasures in Step 1 if needed.
* * * * * * * * * * * *
Mid-term Issues
Issue [1] Prevention of breakage, clogging and water leakage of structural materials (reactor and pipes, etc.) due to corrosion caused by salt.
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(2) Cooling the Spent Fuel Pools
<Step 1 (around 3 months)>
Target [4]: Maintain stable cooling. Countermeasure [22]: Continuation of water injection by Giraffe, etc (reliability improvement (enhanced durability of hoses) / switch to remote-controlled operation.)
Countermeasure [23]: Add cooling function to normal Fuel Pool Cooling system and continue injecting water for Unit 2.
Countermeasure [24]: Examination and implementation of restoration of normal cooling system for Units 1, 3, and 4.
Risk [6]: Possibility of inability to restore normal cooling line due to damages to the building.
Countermeasure [25]: Examination and implementation of installing heat exchangers.
Countermeasure [26]: (Unit 4) Installation of supporting structure under the bottom of the pool.
<Step 2 (around 3 to 6 months after achieving step 1)>
Release of radioactive materials is under control and radiation dose is being significantly held down.
Target [5]: Maintain more stable cooling function by keeping a certain level of water.
Countermeasure [27]: Cooling by installation of heat exchangers.
Countermeasure [28]: Expansion of remote-controlled operation areas of Giraffe, etc.
<Mid-term Issues>
Issue [2]: Removal of fuels (including Units 5 & 6.)
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II. Mitigation (3)
Containment, Storage, Processing, and Reuse of Water Contaminated by Radioactive Materials (Accumulated Water)
Current Status [8]: Leakage of high radiation-level contaminated water assumed to have originated from Unit 2 reactor occurred, but was subsequently stopped.
Countermeasure [29]: Identify leakage path and examine and implement preventive measures. Placing sandbags with radioactive-material adsorption material (zeolite) in the bay. Installing fences in the bay to prevent contamination from spreading (silt fence.) Blockage between trenches and buildings, etc
Current Status [9]: Leakage and accumulation of high radiation level contaminated water at Unit 2’s turbine building, vertical shafts and trenches.
Countermeasure [30]: Transferring accumulated water to facilities that can store it (condenser and Centralized Waste Treatment Facility).
Countermeasure [31]: Preparing decontamination and desalt of transferred accumulated water. (Countermeasure [38])
Countermeasure [32]: Preparing to install tanks.
Current Status [10]: Increase of storage volume of water with low radiation level.
Countermeasure [33]: Preparing to store with tanks and barges.
Countermeasure [34]: Preparing for decontamination and desalt of contaminated water (Countermeasure [41])
Countermeasure [35]: Preparing to install a reservoir.
Current Status [11]: High likelihood of underground water around the building (sub-drainage water) to be contaminated.
Countermeasure [36]: Preparing to decontaminate sub-drainage water after being pumped up.
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Targets, Countermeasures and Risks
<Step 1 (around 3 months)>
Target [6]: Secure sufficient storage place to prevent water with high radiation level from being released out of the site boundary.
Countermeasure [37]: Utilization of Centralized Waste Treatment Facility, etc. to store water.
Countermeasure [38]: Install water processing facilities; decontaminate and desalt highly-contaminated water and store in tanks.
Risk [7]: Possibility of delay in installing water processing facilities or poor operating performance of the facilities.
Countermeasure [39]: Examination and implementation of backup measures (installment of additional tanks or pools or leakage prevention by coagulator, etc.)
Target [7]: Store and process water with low radiation level.
Countermeasure [40]: Increase storage capacity by adding tanks, barges, Megafloat, etc.
Countermeasure [41]: Decontaminating contaminated water using decontaminants to below acceptable criteria.
* * * * * * * * * * * *
<Step 2 (around 3 to 6 months after achieving step 1)>
Target [8]: Decrease the total amount of contaminated water.
Countermeasure [42]: Expansion of additional tanks to store high radiation-level contaminated water.
Countermeasure [43]: Continuation and reinforcement of decontamination and desalt of high radiation-level water.
Countermeasure [44]: Continuation and reinforcement of decontamination and desalt of low radiation-level water.
Countermeasure [45]: Reuse of processed water as reactor coolant.
Countermeasure [46]: Decontamination to the level below criteria level.
<Mid-term Issues>
Issue [3] Installation of full-fledged water treatment facilities.
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II. Mitigation
(4) Mitigation of Release of Radioactive Materials to Atmosphere and from Soil
Current Status [12]: Debris are scattered outside the buildings and radioactive materials are being scattered.
Countermeasure [47]: Inhibit scattering of radioactive materials by full-scale dispersion of inhibitor after confirming its performance by test.
Countermeasure [48]: Prevent rain water contamination by dispersion of inhibitor.
Countermeasure [49]: Removal of debris.
Countermeasure [50]: Examination and implementation of basic design for reactor building cover and full-fledged measure (container with concrete roof and wall, etc.)
Countermeasure [51]: Consideration of solidification, substitution and cleansing of contaminated soil (med-term issues.)
<Step 1 (around 3 months)>
Target [9]: Prevent scattering of radioactive materials on buildings and ground.
Countermeasure [52]: Improvement of work condition by expanding application and dispersion of inhibitors to the ground and buildings.
Countermeasure [53]: Continue removal of debris.
Countermeasure [54]: Begin installing reactor building cover (with ventilator and filter.)
Risk [8]: Considerable reduction of radiation dose is a prerequisite to launch construction (continue countermeasure [52] and [53].)
<Step 2 (around 3 to 6 months after achieving step 1)>
Target [10]: Cover the entire buildings (as temporary measure).
Countermeasure [55]: Complete installing reactor building covers (Units 1, 3, 4.)
Risk [9]: Possibility of cover being damaged by a huge typhoon.
Countermeasure [56]: Begin detailed design of full-fledged measure (container with concrete roof and wall, etc.)
<Mid-term Issues>
Issue [4]: Cover the entire building (as full-fledged measure)
Issue [5]: Solidification, substitution and cleansing of contaminated soil.
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III. Monitoring / Decontamination
(5) Measurement, Reduction and Announcement of Radiation Dose in Evacuation Order / Planned Evacuation / Emergency Evacuation Preparation Areas
Current status [13]: Monitoring of radiation dose in and out of the power station is carried out.
Countermeasure [57]: Monitoring sea water, soil and atmosphere within the site boundary (25 locations.)
Countermeasure [58]: Monitoring radiation dose at the site boundary (12 locations.)
Countermeasure [59]: Consideration of monitoring methods in evacuation order/planned evacuation/emergency evacuation preparation areas. (countermeasure [60] to [63])
<Step 1 (around 3 months)>
Target [11]: Expand/enhance monitoring and inform of results fast and accurately.
Countermeasure [60]: Consideration and implementation of monitoring methods in evacuation order / planned evacuation / emergency evacuation preparation areas (in cooperation and consultation with national/prefectural/municipal governments.)
Countermeasure [61]: Announce accurately monitoring results of long half-life residue radioactive materials such as cesium 137.
<Step 2 (around 3 to 6 months after achieving Step 1)>
Target [12]: Sufficiently reduce radiation dose in evacuation order / planned evacuation / emergency evacuation preparation areas.
Countermeasure [62]: Monitoring of homecoming residences in cooperation and consultation with national / prefectural / municipal governments.
Countermeasure [63]: Examination and implementation of necessary measures to reduce radiation dose (decontamination of homecoming residences and soil surface) in cooperation and consultation with national / prefectural / municipal governments.
<Mid term issues>
Issue [6]:Continue monitoring and informing environmental safety.
(Note) With regard to radiation dose monitoring and reduction measures in evacuation order/planned evacuation/emergency evacuation preparation areas, we will take every measure through thorough cooperation with the national government and by consultation with the prefectural and municipal governments.
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Chapter 2: International Atomic Energy Agency (IAEA) Statements on the Fukushima Nuclear Accident Through mid-April
Editor's Note: The following press release statements from the International Atomic Energy Agency (IAEA) are reprinted with the permission of the IAEA.
INES - The International Nuclear and Radiological Event Scale
What is INES?
INES is a tool for promptly communicating to the public in consistent terms the safety significance of reported nuclear and radiological incidents and accidents, excluding naturally occurring phenomena, such as radon. The scale can be applied to any event associated with nuclear facilities, as well as the transport, storage and use of radioactive material and radiation sources. Access to INES
What is the purpose of the INES Scale?
The primary purpose of the INES Scale is to facilitate communication and understanding between the technical community, the media and the public on the safety significance of events. The aim is to keep the public, as well as nuclear authorities, accurately informed on the occurrence and potential consequences of reported events.
How does INES operate?
The scale was designed by an international group of experts first convened jointly in 1989 by the IAEA and the Nuclear Energy Agency of the Organisation for Economic Co-operation and Development (OECD/NEA). Since then, the IAEA has overseen its development in cooperation with the OECD/NEA and with the support of more than 70 designated INES National Officers who officially represent the INES Member States in biennial technical meetings.
Why use INES?
INES, to facilitate understanding, uses a numerical rating to explain the significance of nuclear or radiological events. This is just like using ratings for earthquakes or temperature, which would be difficult to understand without the Richter or Celsius scales.
INES applies to any event associated with the transport, storage and use of radioactive material and radiation sources. Such events can include industrial and medical uses of radiation sources, operations at nuclear facilities, or the transport of radioactive material.
Events are classified at seven levels: Levels 1–3 are “incidents” and Levels 4–7 “accidents”. These levels consider three areas of impact: people and the environment, radiological barriers and control, and defence in depth. The scale is designed so that the severity of an event is about ten times greater for each increase in level on the scale. Events without safety significance are called “deviations” and are classified Below Scale/Level 0.
Who is eligible to participate in INES?
Participation is open to all IAEA Member States since INES covers a wide spectrum of practices, including industrial use such as radiography, use of radiation sources in hospitals, operations at nuclear facilities and transport of radioactive material. Participation in the INES system is voluntary.
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IAEA Briefing on Fukushima Nuclear Accident (20 April 2011, 16:00 UTC)
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. 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.
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.
IAEA Briefing on Fukushima Nuclear Accident (19 April 2011, 18.00 UTC)
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 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. 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
IAEA Briefing on Fukushima Nuclear Accident (18 April 2011, 15:35 UTC)
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.
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IAEA Briefing on Fukushima Nuclear Accident (15 April 2011, 14:30 UTC)
15 April 2011
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 12th April and continued on 13th 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 13th 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 11th 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 13th April and for Units 1 and 2 on 14th April.
As of 14th April, white smoke was still observed coming from Units 2 and 3. White smoke was also observed coming from Unit 4 on the 14th April.
On 13th April, Japan’s Nuclear and Industrial Safety Agency (NISA) reported that the Tokyo Electric Power Company (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 95oC). In Unit 1, the temperature at the feed water nozzle of the RPV is 197oC and at the bottom of the RPV is 119oC. In Unit 2, the temperature at the feed water nozzle of the RPV is 150oC. In Unit 3 the temperature at the feed water nozzle of the RPV is 91oC and at the bottom of the RPV is 121oC.
On 14th 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 14th 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 14th 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 14th 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 14th 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 12th 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 14th 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 14th 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 14th April for a total of 50 samples taken from 11th - 14th April. Analytical results for all of the samples of various vegetables, mushrooms, fruits (strawberry), 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 14th 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. On some days, two samples were collected at the same sampling point, a few hours apart and analysed separately.
Until 3rd April a general decreasing trend in radioactivity was observed at the sampling points TEPCO1 to TEPCO4. After the discharge of contaminated water on 4th April, a temporary increase in radioactivity was reported. Since 5th April, a general downward trend in the concentration of radionuclides in sea water for all TEPCO sampling points has been observed.
On 15th April, new data for TEPCO1-4 sampling points have been reported. At all four locations, the concentration of both I-131 and Cs-137 measured on the 12th 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 23rd March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4th April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B.
The most recent results reported on 11th 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 MEXT4. For other sampling locations I-131 was reported at levels below about 15 Bq/l.
On 15th April, no new data from any MEXT sampling points have been reported.
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, 15th April at 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 interagency collaboration and coordination during the Japanese nuclear emergency and called for strengthening cooperation in future remediation actions.
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IAEA Briefing on Fukushima Nuclear Accident (14 April 2011, 15:30 UTC)
14 April 2011
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 13th April
NISA press release reported that an earthquake occurred at Hamadori in Fukushima prefecture on April 13th, 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 NPP 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 1-3. The transfer of contaminated water from Unit 2 turbine building to the condenser was started (12th April) and suspended (13th 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 till 10:00 13th 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 13th April).