IAEA Fukushima Daiichi Status Report
31 August 2012
The IAEA issues regular status reports to the public on the current status of the Fukushima Daiichi Nuclear Power Plant, including information on environmental radiation monitoring, the status of workers, and current conditions on-site at the plant.
The information cited in this report is compiled from official Japanese sources, including the Ministry of Economy, Trade and Industry (METI), the Nuclear and Industrial Safety Agency (NISA), the Ministry of Education, Culture, Sports, Science and Technology (MEXT), the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), the Ministry of Health, Labour and Welfare (MHLW) and the Ministry of Foreign Affairs (MOFA) through the Japanese Permanent Mission in Vienna and the Cabinet's Office of the Prime Minister. Information is also provided by the Tokyo Electric Power Company (TEPCO), the operator of the Fukushima Daiichi Nuclear Power Plant.
Questions on the information provided in this report may be directed to [email protected].
Accident Investigation Reports
Release of Updated TEPCO Fukushima Accident Investigation Report
Previously TEPCO established the "Fukushima Nuclear Accidents Investigation Committee" and "Nuclear Safety and Quality Assurance Meeting Accident Investigation Verification Committee". In December 2011 they released an interim report on the accident.
On 20 June 2012 TEPCO announced the release of the Fukushima Nuclear Accidents Investigation Report. This report and its annexes are currently only available in Japanese.
Release of National DIET of Japan Fukushima Nuclear Accident Independent Investigation Commission Report
Previously the National DIET of Japan appointed an independent investigation committee to investigate the accident at TEPCO’s Nuclear Power Station. On 5 July the commission released their report to the Japanese Government. Currently only the executive summary of this report is available in English online.
Final Report of Investigation Committee on Accident at Fukushima Nuclear Power Stations of Tokyo Electric Power Company
On 26 December 2011 the Investigation Committee on the Accident at the Fukushima Nuclear Power Stations of Tokyo Electric Power Company released their interim report (which was translated into English later). On 23 July 2012 their final report was released in Japanese. On the same date the committee released their recommendations from their final report in English.
Updated Roadmap Document
On 2 August the Nuclear Emergency Response Headquarter Government-TEPCO Mid-and-long Term Response Council released an updated version of the Progress Status of Mid-and-long Term Roadmap towards the Decommissioning of Fukushima Daiichi Nuclear Power Units 1-4, TEPCO document. This document notes the following updates (many of which have been discussed in previous status summary updates):
- TEPCO is currently considering installing a groundwater bypass system that will pump water flowing towards the reactor buildings around the buildings (preventing groundwater ingress). Equipment design and ground water quality were expected to be assessed until the end of July and installation was to begin in August;
- An Advanced Liquid Processing System (ALPS) for the removal of α and β emitters from waste water has been installed onsite (no date of completion was given). Test evaluation of the system to confirm performance is currently taking place before full operations begin;
- To prevent the spread of oceanic contamination installation of an impermeable wall has begun in the area offshore. Landfilling activities began in late April and boring for steel pipe forepole [sic] casts began in early July. Wave absorbing blocks will be installed later;
- The seabed soil in front of the intake channel has been covered and solidified. Seabed soil in front of the intake channel of Units 1-4 has been covered (as per soil solidification efforts discussed in previous summaries). Radioactive material concentration in the soil has been gradually decreasing since April 2011. Concentration monitoring is continuing in this area as a rapid decrease in soil concentration has not been measured following the covering work;
- TEPCO is currently developing plans to close the Unit 2 Reactor Building blowout panel. A survey of the area has been conducted and a detailed design of the closing process is underway. The installation of scaffolding for the closing of the panel and the installation of ventilation equipment is expected to take place between October 2012 and March 2013;
- Rubble removal from the top of the Unit 3 Reactor Building is expected to be complete towards the end of 2012;
- In June additional protective platforms were installed at the top of the Unit 4 Spent Fuel Pool. The cover is designed to protect the pool during the demolition of the damaged roof area. Figure 1 shows the installation of the platform and the area that is scheduled for demolition;
Figure 1: Installation of protective platform above Unit 4 Spent Fuel Pool
- In July two fresh fuel elements stored in the Unit 4 Spent Fuel Pool were removed. Currently these elements are undergoing testing for traces of corrosion. Testing is expected to be complete in September;
- Surveys of the 3rd, 4th and 5th floor of the Unit 2 Reactor Building have taken place. The highest dose rate measured was 880 mSv/h directly above the reactor well;
- A temporary cask custody area to store dry spend fuel casks from the Common Spent Fuel Storage Pool is currently being constructed. Foundation work, crane installation, electrical work and protective measure installation work are expected to be on-going until the end of November;
- Decontamination tests (using stabilized cesium) were planned to take place in mid-July. These tests are part of overall efforts to develop a decontamination strategy for the inside of the reactor buildings. Results from the tests have not been released as of the publication of this status summary;
- Tests of various methods to solidify secondary waste are on-goig;
- Turnover of employees whose total accumulated dose exceeded 75 mSv began in October 2011 to comply with the mandated limit of 100 mSv/5-yr. As of April 2012, approximately 300 employees had total doses in excess of 75 mSv. As of 1 June 192 of those employees have been turned over [sic];
- Unit 1-3 have remained in cold shutdown condition. The temperatures measured near the RPV bottoms have had very small rises in temperature due to the increase in the ambient air temperature outdoors. Parameters such as PCV pressure and radioactive material release rate from the PCVs have shown no significant changes; and
- The total currently release rate of radioactive material from the PCV of Units 1-3 is estimated to be at maximum 0.01 Billion Bq/h. Unit 1 is estimated to be 0.0002 Billion Bq/h, Unit 2 is estimated to be 0.008 Billion Bq/h and Unit 3 is estimated to be 0.0003 Billion Bq/h. Radiation exposure at the site boundary due to these releases is currently assessed to be 0.02 mSv/h (which excludes all radioactive material released already). Figure 2 shows the trend of the total release rate of radioactive material from Units 1-3 since July 2011.
Figure 2: Trend of release rate of radioactive material from Units 1-3 since June 2011
Recent Operations in Unit 1
On 23 July TEPCO provided the results of a radionuclide analysis of water samples taken from the Unit 1 Turbine Building.
On 8 August TEPCO provided information on their recent investigation to establish the conditions of the operating floor (5th floor) of the Unit 1 Reactor Building. This investigation is part of the planning process for the removal of fuel from the Unit 1 Spent Fuel Pool. To conduct their investigation TEPCO mounted a large balloon with several cameras and attempted to float it up to the 5th floor via an equipment hatch. The balloon was unable to reach the 5th floor due to debris blocking it near the top which is presumed to be part of a cable. Figure 3 shows a schematic of the survey. Figure 4 shows the balloon equipment in use. Figure 5 shows some of the images that were captured by the balloon:
Figure 3: Schematic of survey route (area where obstacle was encountered is indicated)
Figure 4: Exterior images of balloon survey apparatus
Figure 5: Images captured by balloon survey apparatus
High resolution images from this survey are also available online.
On 9 August TEPCO provided results from a radionuclide analysis of material in air samples from the Unit 1 Reactor Building.
On 9 August TEPCO provided results from a radionuclide analysis of gas samples from the Unit 1 PCV Gas Control System.
Recent Operations in Unit 4
On 10 August TEPCO conducted an operation to remove the PCV Lid from the Unit 4 reactor PCV. The removal took approximately 25 minutes. Figure 6 shows the PCV being lifted out of the building by a crane:
Figure 6: Images captured during PCV lid removal
On 13 August TEPCO provided results of a radionuclide analysis of water samples taken from the Unit 4 Turbine Building Basement.
On 14 August TEPCO reported that a water leak was discovered at the Unit 4 Turbine Building. The leaked water spread to all area of the power center room and north side of the Unit 4 Turbine Building first floor corridor. A radionuclide analysis of the water yielded results of 3.0 x104 Bq/cm3 and 4.7 x 104 Bq/cm3 of Cs-134 and Cs-137 respectively. Volume estimates for the leak were not provided.
Management of On-site Contamination
Water Leak at Tank Storage Area for Concentrated Water From Reverse Osmosis Membrane Desalination System
On 5 April TEPCO reported that a new leak was discovered from a pipe leading to the water tank storage area for the concentrated water from the Reverse Osmosis Membrane Desalination System. This leak was approximately 12 m3 in volume. The leaked water is estimated to have the same approximate activity as the water leak from 26 March 2012.
On 27 April TEPCO reported that another water leak was discovered at the Reverse Osmosis Membrane Desalination System at the tent warehouse. 36 L of water was estimated to have leaked. The γ dose rate at the surface of a puddle at the leak was measured to be approximately 1 mSv/h and the β dose rate was measured to be approximately 7 mSv/h. Figure 7 shows the location of this leak:
Figure 7: Location of leak reported on 27 April at Reverse Osmosis Membrane Desalination System tent warehouse
On 17 August TEPCO reported that a new water leak was discovered at the Reverse Osmosis Membrane Desalination System. Approximately 0.2 m3 of water had leaked. A surface measurement found a γ dose rate of 0.1 mSv/h and a β dose rate of 3 mSv/h. Figure 8 shows the location of the leak in the system:
Figure 8: Location of leak reported on 17 August at Reverse Osmosis Membrane Desalination System
Higher resolution images of the damaged joint are available online.
Smoke From Cesium Absorption Tower Temporary Storage Facility
On 14 August TEPCO reported that smoke was seen coming from the general area of the cesium absorption tower temporary storage facility. The source of the smoke was identified to be a pump which was immediately sprayed with a fire extinguisher. Fire fighters were called it to verify that there was no fire. The pump was replaced several hours later and this event had no impact on operations at the site. Figure 9 shows the location of the cesium absorption tower temporary storage facility and Figure 10 shows the pump:
Figure 9: Location of cesium absorption tower temporary storage facility
Figure 10: View of pump where smoke was discovered on 14 August
Monitoring of Workers
Increasing ADP Visibility
Previously TEPCO had learned that allegedly some contractors were wearing small lead shields around their Alarming Personal Dosimeters (APDs). On 24 July the Ministry of Health, Labour and Welfare asked TEPCO to look into countermeasures that would increase the visibility of the APD and prevent workers from using such methods in the future to reduce their reported doses.
On 31 July TEPCO provided a brief report indicating their proposed methodology to prevent instances of intentional shielding of active dosimetry equipment. The conclusions from this report state that beginning in October 2012, when workers are working in high radiation environments they will be required to wear ‘chest-transparent’ protective clothing (except in those cases when they are wearing radiation shielding protective clothing such as a tungsten vest).
TEPCO considered taping the ADP inside a plastic bag to the outside of the workers normal disposable protective equipment. The ADPs that are currently in use on site are required to be tied around a workers neck. This requirement is to ensure that ADPs are not mixed up between workers during PPE removal. It was determined that attaching the ADP to the outside of the disposable suit created a safety hazard as the ADP may fall off the suit and get caught in rotating machinery potentially injuring workers with instruments tired around their necks.
On 10 August TEPCO provided further information discussing their current efforts to verify that workers are properly using their APD units. Figure 11 summarizes this information:
Figure 11: Measures in place by TEPCO to verify proper APD use
Video footage of the entry and exit procedures showing workers inspecting for APDs on colleagues is available online in three parts (part 1, part 2, part 3 and TEPCO has also provided an overview of the footage).
On 13 August TEPCO provided a report on the potential impact a 3mm lead shield placed around an APD would have on measured readings based on experiments they conducted. This report is only available in Japanese. Figure 12 shows the design of a 3mm lead shield for the APD and how it could potentially be unnoticed under a disposable suit, Figure 13 shows an experiment setup with three pairs of APDs (shielded and unshielded) and Figure 14 shows the readings on a shielded and unshielded APD from that experiment.
Figure 12: Design of 3mm lead shield for APD and potential to be hidden under disposable clothing
Figure 13: Experiment setup to test shielded versus non-shielded APD
Figure 14: Results from experiment of shielded versus non-shielded APD (shielded APD is on right)
On 31 July TEPCO provided estimated doses to workers onsite for the period between March 2012 to June 2012. Table 1 compiles the external dose data reported between March 2011 to May 2012. Please see the linked document and the previous status summary reports for more detailed dosimetry information.
Table 1: External doses reported by TEPCO between March 2011 and June 2012:
|Number of People With External Doses Within Ranges Reported by TEPCO|
|Greater Than 250||0||0||0||0||0||0||0||0||0||0||0||0||0||0||0||0|
|Less Than 10||2 242||4 876||6 385||6 827||7 304||6 997||6 869||6 451||5 931||6 105||5 623||5 611||5 608||5 251||5 470||5 787|
|Total Personnel Reported||3 745||5 752||6 987||7 227||7 543||7 147||7 003||6 562||6 017||6 178||5 696||5 704||5 648||5 302||5 508||5 797|
|Max Dose Reported||199.42||85.29||59.18||39.62||36.76||29.25||35.50||35.30||20.39||23.20||18.98||18.81||19.06||23.53||16.85||12.11|
|Average Dose Reported||13.66||5.14||3.56||2.85||2.07||1.83||1.73||1.65||1.35||1.27||1.26||1.31||1.16||1.06||1.17||1.04|
Protective Measures for Public
Presentation on Designating and Rearranging Areas of Evacuation
On 23 July the Support Team for Residents Affected by Nuclear Incidents released a presentation on the designation and rearrangement of the evacuation areas. This presentation summarizes the actions that took place during the response to the accident and follows the changes to the evacuation areas that have been made following the initial response. This presentation is available from METI online.
Current Status of Evacuation Areas
On 15 June 2012 the Nuclear Emergency Response Headquarters announced changes to the designation of evacuation areas in Iitate Village. These changes were planned to occur on 17 July. It was also announced that Narah Town would have changes to its designation of evacuation areas on 10 August. Figure 15 shows the current evacuation boundaries and identifies which areas changed in July and August:
Figure 15: Current evacuation areas (as of 27 August 2012)
The previous maps of the evacuation areas are available in previous reports and online.
Radiation Monitoring of Foodstuffs
Radionuclide Analysis of Fish and Shellfish
On 31 June TEPCO provided results from their analysis of fish and shellfish samples collected on 9 and 15 July 2012. Table 2 provides some of these results.
Table 2: Results from fish and shell fish samples taken by TEPCO on 9 and 15 July:
Date of Sample
|1||Common Skete (Muscle)||Approx. 2km Offshore
Daini NPS (T-S7)
|2||Sea Bass (Muscle)||Approx. 2km Offshore
Daini NPS (T-S7)
|3||Banded Dogfish (Muscle)||Approx. 2km Offshore
Daini NPS (T-S7)
|4||Drumfish (Muscle)||Approx. 2km Offshore
Daini NPS (T-S7)
|5||Microstomus Achne (Muscle)||Approx. 2km Offshore
Daini NPS (T-S7)
|6||Flatfish (Muscle)||Approx. 2km Offshore
Daini NPS (T-S7)
|7||Dasyatis Matsubarai (Muscle)||Approx. 2km Offshore
Daini NPS (T-S7)
|8||Marbled Sole (Muscle)||Approx. 2km Offshore
Daini NPS (T-S7)
|9||Barfin Flounder (Muscle)||Approx. 2km Offshore
Daini NPS (T-S7)
|15 July||670||1 000||1 670|
|10||Greenling (Muscle)||Approx. 10km Offshore
|11||Stone flounder (Muscle)||Approx. 10km Offshore
|12||Lepidotrigla Microptera (Muscle)||Approx. 10km Offshore
|13||Lophius Litilon (Whole)||Approx. 10km Offshore
|14||Common Skete (Muscle)||Approx. 10km Offshore
|15||Microstomus Achne (Muscle)||Approx. 10km Offshore
|16||Greenling (Muscle)||Approx. 2km Offshore
|17||Common Skete (Muscle)||Approx. 2km Offshore
|18||Pennahia Argentata (Muscle)||Approx. 2km Offshore
|19||Sebastes Cheni (Muscle)||Approx. 2km Offshore
|15 July||640||990||1 630|
|20||Banded Dogfish (Muscle)||Approx. 2km Offshore
On 21 August TEPCO provided results from their numerous analysis of fish and shellfish samples collected offshore on 18 and 23 July and 1 August. In this specific collection of results there is a sample of Greenling (Muscle) collected approximately 1 km offshore of Ota River which resulted in a measurement of Cs-134 activity of 9800 Bq/kg and Cs-137 16000 Bq/kq for a combined activity of 25800 Bq/kg wet weight (raw). Figure 16 is the sample of Greenling that was captured.
Figure 16: Sample of Greenling that measured 25800 Bq/kg of cesium
On 28 August TEPCO provided a document summarizing the results of the fish sampling they have conducted between 29 March and 1 August 2012.
IAEA Comments on 25 800 Bq/kg Measurement
There has been a large volume of media interest in this specific fish sample after it was reported by TEPCO. As is visible in the results reported by TEPCO this measurement is unique amongst other much lower measurements ranging from a few Bq/kg, below detection or up to 490 Bq/kg. Unusually high values amongst bottom dwelling fish in this region are not an unexpected consequence from the accident. Such fishes are scavengers and will catch and eat small fish and other bottom-dwelling animals such as crabs. This case may be the result of the two small analysed fish having eaten some hot particles from the sediment. If you compare these values with the others that have been reported these results appear as outliers but some in the media have only reported on these specific outliers and not discussed the majority of the results which are much lower.
This fish was caught in the region near the Ota river which appears to discharge into this coastal area from land, where high terrestrial contamination occurred directly after the accident which could also lead to this unexpected high value. Seawater in this region also measured higher radiocesium concentrations of up to 240 mBq/L of Cs-137 and 100 mBq/L in measurements on 3 and 17 July in bottom water respectively. This discharge conclusion may not be valid as the other species caught in the same location do not also indicate such high levels. On page 2 and at the top of page 4 of the TEPCO document other results from Greenling are available and they are about the expected level which is lower than this outlier sample. This sample is not seen as really alarming because such outliers do not reflect the general situation of levels in fish.
Figures 17, 18 and 19 have been provided by TEPCO which further indicate that this measurement as an outlier:
Figure 17: Summary of results for Greenling and Sea Bass
Figure 18: Summary of results for Common Skete and Pacific Cod
Figure 19: Summary of results for Flatfish and Microstomus Achne
Food monitoring data were reported by the Ministry of Health, Labour and Welfare (MHLW) on 17 – 20, 23 – 27, 30 and 31 July and 1 – 3, 6 – 10, 13 – 17, and 20 – 24 August for a total of 26034 samples collected from 46 different prefectures in Japan (Table 3).
Analytical results for 25845 (over 99%) of the 26034 samples indicated that Cs-134 and Cs-137 were either not detected or were below the standard limits for radionuclides set by the Japanese authorities. However, 189 samples were above the standard limits for radionuclides Cs-134 and Cs-137 (Table 4).
Updated information was reported by the MHLW on 19, 26 and 27 July and 2, 7, 9, 10, 15 and 23 August 2012 placing restrictions on the distribution of:
- silver crucian carp taken from specific rivers and water-bodies in Chiba prefecture;
- meat of sika deer captured in Iwate prefecture;
- starspotted smoothhound and vermiculated puffer fish taken offshore of Fukushima prefecture;
- meat from bears captured in specific parts of Fukushima prefecture;
- Japanese eel captured in a river and its branches in Fukushima prefecture;
- mushrooms collected from the wild in specific areas of Fukushima and Tochigi prefectures, and
- land-locked salmon (excluding farmed fish) captured in a river and its branches in Tochigi prefecture.
On 24 July and 20 August 2012, the MHLW indicated the lifting of restrictions on the distribution of tea leaves produced in a specific part of Ibaraki prefecture. On 26 July, it was indicated that restrictions on the distribution of rice (grown in 2012) were partially lifted in parts of Fukushima prefecture. However, rice production remains subject to controls under the Fukushima prefectural management plan. A summary of the status of food restrictions reported since March 2011 is available online.
Table 3: Samples Collected by Prefecture of Origin as Reported by the Ministry of Health, Labour and Welfare between 17 July and 24 August 2012:
|Prefectures||Number of Samples|
|Prefectures||Number of Samples|
|Not Known||1 008|
Table 4: Samples above the Standard Limits for Radionuclides in Food as Reported by the Ministry of Health, Labour and Welfare between 17 July and 24 August 2012:
|Number of Samples Above
Standard Limits for Radionuclides
Cs-134 + Cs-137
Japanese Black Porgy
Japanese Eel (Wild)
Asian Black Bear
Japanese Black Porgy
Northern Sea Urchin
Ocellate Spot Skate
Red Tongue Sole
Silver Crucian Carp
Sika Deer Meat
Sika Deer Meat
Changeable Tuft Mushroom