Increases in perinatal mortality in prefectures contaminated by the Fukushima nuclear power plant accident in Japan
While fetal and neonatal deaths within the first week of life (termed perinatal mortality) have been decreasing in Japan consistently since 2002, data examined in Fukushima-affected areas during 2012-2015 show a break in this trend with an increase that, as of 2015, had not reversed.
This recent study examines numbers of perinatal deaths in areas affected by the ongoing Fukushima nuclear catastrophe and compared these data to other areas of Japan supposedly unaffected.
This research is just the latest showing a perinatal mortality increase following Fukushima. A number of studies in Europe also showed similar increases following the Chernobyl nuclear catastrophe.
Increases in perinatal mortality in prefectures contaminated by the Fukushima nuclear power plant accident in Japan
Radioactively-hot Particles Detected in Dusts and Soils from Northern Japan by Combination of Gamma Spectrometry, Autoradiography, and SEM/EDS Analysis and Implications in Radiation Risk Assessment
Authors:
Dr. Marco Kaltofen – Nuclear Science and Engineering Program, Dept. of Physics, Worcester Polytechnic Institute
Arnie Gundersen – Chief Engineer, Fairewinds Energy Education, Community Research Fellow University of Vermont
Complete Methodology:
The purposes of the study were to identify and collect samples with a high potential to contain radioactively-hot particles for microscopic examination, to determine if local hot spots of contamination existed at the time of the Fukushima Dai-ichi meltdowns, and finally to document whether any hot spots persisted five years after the accidents.
Samples of 180 Japanese house dusts, car engine filters, HVAC filters, street dusts and fine surface soils were collected and shipped to Worcester Polytechnic Institute for radioisotope analysis. A total of 235 US and Canadian samples of similar matrices were collected between 2011 and 2015. Of these 180 Japanese particulate matter samples, 57 were automobile or home air filters, 59 were surface dust samples, 29 were street dusts (accumulated surface soils and dusts) and 33 were vacuum cleaner bag or other dust samples. All filters were in service on or after March 11, 2011, the date of the initial releases from the Fukushima Dai-ichi reactors.
Of the 180 samples from Japan, 108 were collected in Japan during 2016 while the remaining 72 samples were collected during 2011. These samples included fine surface soils, sediments from drainage areas, and soils from floor mats. Dusts were collected from bulk and surface dust accumulations; including air handling fans, residential air filters, vacuum cleaner bags, automobile air filters, public restroom ventilation fans and from surfaces at public transportation points throughout northern Japan. This study used a mix of samples submitted by volunteers and by the authors. There were controls on the volunteers’ methods used to select samples, however direct sampling oversight was limited. Fifteen scientists and volunteer citizen-scientists collected these samples in areas across Japan, but predominantly in Fukushima Prefecture and Minamisoma City. Sampling locations were in publicly-accessible areas such as bike paths, roadways, sidewalks and public buildings. Permits were received to sample in restricted areas where post-Fukushima meltdown decontamination work was in progress. A majority of these samples were collected from locations in decontaminated zones cleared for habitation by the National Government of Japan.
Sample collection
Sample collection was biased by performing a preliminary visual survey to facilitate collection from areas where fine particulate matter can accumulate, such as low spots on roads or rooftops, air handling fan blades, floor mats and rooftops. For the 2016 sample set (108 of 180 samples), an International Medcom Inspector Alert surface contamination monitor (radiation survey meter) was used to identify samples from within low lying areas and on contaminated outdoor surfaces. Screening introduces a bias to the soil sample set allowing for maximum probability of collecting particulate matter that might contain hot particles. Indoor dusts, HVAC system dusts and auto air filters were randomly selected and no survey meters were used nor were surface radiation measurements taken prior to dust sample collection.
At the time of the 2016 sampling campaign, mapped surface activity data was available from Safecast, an open citizen-led group that collected activity data via a standardized device of their own design, the bGeigie. Uncontaminated areas in Japan (as mapped by safecast.org) have bGeigie-measured activities on the order of 0.08 uSv/hr. or less. Areas of known contamination are on the order of 0.16 uSv/hr. and higher. More than 90 percent of the samples in this study come from the areas Safecast-mapped as 0.16 uSv/hr. and higher (Figure 1). This indicates that the data are more representative of the contaminated zone, rather than of Japan as a whole. Mapping via the Safecast bGeigie proceeds with a plastic alpha and beta shield around the detector element. This makes the device essentially a gamma activity monitor. Thirteen of the 2016 samples from Japan were measured by the primary instrument (Ortec NaI well gamma photon detector) and the bGeigie. With the shield present on the bGeigie so that both devices measured gamma energy only, the R2 value between the two sets was 0.97, a good fit (Figure 2). Without the shield the bGeigie also accumulated beta and alpha energy, so the fit was poorer, with R2 = 0.15. The strong correlation between the bGeigie in gamma mode and the Ortec spectrometer is added evidence that the sampling methodology provides data that is more representative of the contaminated areas in northern Japan, and less so for Japan as a whole.
For each 2016 sample collection location point, a photograph was taken to provide an image of where the sample was collected as well as a record of the GPS location. All Japanese samples were air dried at ambient temperature prior to analysis, then shipped internationally to Worcester Polytechnic Institute in Worcester, MA, USA, for analysis.
Motor vehicle engine air filters process large volumes of air. In Japan private vehicles average 65 liters of gasoline use per month. (Schipper 2009) This fuel requires approximately 638 cubic meters of air for complete combustion. This is about 30 cubic meters per day, which is in the same order of magnitude as a working adult tidal air volume of 10 to 20 cubic meters per day. It was hypothesized that engine air filters in routine use and first installed prior to March 11, 2011 would provide an approximation of the amount of radioactive dusts present in ambient air for each driving region.
Bulk dust and street dust/soil samples were air dried at ambient temperatures prior to analyses. Dust samples containing macroscopic objects and excessive pet hair were sieved to pass a 150 micron brass ASTM #100 screen. Samples were divided and separately screened by gamma spectroscopy to determine if activity was heterogeneously distributed within samples. Samples were sequentially divided if necessary, based on gamma-screening results.
Dust was mechanically removed from automobile and HVAC filters. Motor vehicle air filters varied in usage from nearly new to as much as 55,000 logged kilometers of use. Sample results for dust samples were reported on a kBq kg-1 basis. Eight filter samples with detectable activities but with dust that could not be quantitatively removed from filter media were assigned a dust mass of 1.0 g. This introduced a low bias to these samples. Nine samples had activities greater than 0.25 MBq kg-1. To ensure safe transport, these samples were mass-limited to 3 grams before shipping from Japan.
Included in this set of nine atypically-radioactive samples, was a 300 mg sample of street dust received from a location about 10 km from the Fukushima-Dai-ichi accident site in Namie-machi, Futaba-gun, Fukushima Prefecture. This is in the restricted zone, close to but just outside of the exclusion zone. A very similar sample was collected from Iitate. The particulate matter samples were analyzed by sodium iodide gamma spectrometry. One vacuum bag received from a home in Nagoya, Japan, yielded subsamples with no detectable radioactivity above background, despite a sizable amount of activity for the bag as a whole. (Nagoya is 433 km from Fukushima Dai-ichi). By sample division and hot particle isolation with a pancake detector, a single 1 cm by 2 cm glass slide was prepared, with a small number of microscopic dust particles (with activity > 1 MBq ug-1) mounted via double sided adhesive tape.
Analyses of the samples proceeded sequentially by NaI gamma spectrometry, autoradiography of high activity samples, and scanning electron microscopy / energy dispersive X-ray analysis (SEM/EDS) of individual radioactively-hot particles identified by autoradiography (Moody 2015). Autoradiographs were prepared from the highest specific activity samples using blue-sensitive X-ray film, followed by SEM/EDS analysis of autoradiographically positive portions of the sample. Air filter media that had positive gamma spectrometry results were mounted in a single layer onto double sided adhesive paper sheets. These sheets with dusts were then attached to 3 mm thick copper plates. Vehicle and HVAC air filters were prepared by cutting the filter media from their frames, and mounting the filter media on 3 mm thick copper plates. A sheet of blue-sensitive Xray film was sandwiched with the mounted filters, and exposed in a dark photographer’s box for seven days. The autoradiographs used MidSci® classic blue autoradiography film BX and D76 processing.
All gamma spectrometry data are corrected for geometry, and were standardized against a known activity of 137Cs. Gamma photon analyses used Ortec® NaI and Canberra® GeLi flat plate photon detectors. An Ortec® NaI well detector and 1K MCA were also used. Counting efficiency @ 662 keV was found to be 30% based on use of a certified calibration standard from an Eckert & Ziegler Isotope Products standard source, manufactured and certified on Sept. 12, 2011, with 40.12 nCi of 137Cs. The 137Cs in the standard used for quantitation and any Fukushima-related 137Cs in the samples were of the same approximate age, therefore no 137Cs decay correction is warranted in this five-year study. Nuclides not amenable to gamma spectrometry, such as strontium, were not analyzed in this study.
Samples with evident gamma spectral peaks for uranium, thorium or plutonium were selected for SEM/EDS analyses. All particles were mounted as a monolayer on a 25 mm OD Ted Pella, Inc., PELCO® tape tab-covered aluminum SEM stub. If necessary to improve particle conductivity, the samples were carbon or gold coated prior to SEM/EDS analysis. SEM/EDS work was tested commercially at Microvision Laboratories of Chelmsford, MA, using a Bruker® X-Flash® Peltier-cooled silicon drift detector (SDD). The electron beam current was 0.60 nAmperes, accelerated at a voltage of < 0.5 to 60 keV.
Want to look at the numbers? Click below to download the complete data sheet of our samples (.xlsx).
Activities as radio-cesium
Maps of Safecast data and sample sites in Japan
Above-left) Safecast map with dark blues representing low contamination
(Above-right) Map of study sample areas using same Safecast color scheme
Boat tracks and other clutter have been removed from this graphic.
Japan Radiation Interactive Map
(Above) Browse the location, supplementary info and photographs of samples taken in Japan with our interactive sample map created by Ben Shulman-Reed, Fairewinds Energy Education program researcher.
Safecast bGeigie data vs. Ortec NaI gamma spectroscopy data
Japanese dusts and sediments presented by specific activity in kBq kg-1
Distribution of total radiocesium activities in particulate matter samples from Japan
Gamma spec Ibaraki Prefecture, analyzed April 11, 2011
Tokyo vehicle air filter image (Left) and 7 day exposure autoradiograph (Right) Corresponding auto exposed points on the X-ray film are connected by red lines.
SEM image of hot particle, magnification 5000 X.
(Top) SEM/EDS spectrum showing one nodule of hot particle with 15.6% Cs, 16.7% Te, 1.2% Rb, 0.61% Po. (Bottom) second nodule with 48% Te, 1.2% Po, 0.18% Dy (analyzed 12/18/2013).
To read more at :
http://www.fairewinds.org/stoten-methods/
http://www.sciencedirect.com/science/article/pii/S0048969717317953
Fukushima Disaster March 11th – March 21st NRC ET Chronology Descending – Pages From C142487-03X
38 pages Uploaded by Enformable on May 15, 2012
Ministry pushes farmers to attain certification to supply food for Tokyo Olympics
The agriculture ministry has stepped up efforts to certify more agricultural producers in preparation for the 2020 Tokyo Olympics and Paralympics, as the number of meals to be served for athletes and staff will likely exceed 15 million, the amount distributed during the 2012 London Games.
Agricultural producers supplying food for the upcoming quadrennial sporting events are required to obtain certificates under the Good Agricultural Practices third-party system to guarantee safety.
In Japan, about 4,500 farmers and farming organizations have acquired either the Global GAP, issued by a German association, or the Japan GAP (JGAP), managed by the Japan GAP Foundation. This is likely to fall short of the number of producers needed in the 2020 Games, sources familiar with the situation said.
A big obstacle is the expense of obtaining the certificates, with close to ¥100,000 in screening fees needed for the JGAP.
In March, the organizing committee for the Tokyo Games announced a decision to use food made by GAP-certified producers for meals to be served at the Olympic village and other related facilities.
With the current situation, Japan would have to procure a considerable amount of food from abroad, the sources said.
The ministry has set a goal of more than tripling the number of certified agricultural producers from the current level by the fiscal year ended March 2020.
In addition to providing subsidies to cover JGAP screening fees, the ministry plans to give priority to producers aiming to obtain GAP certificates in specific subsidy programs in fiscal 2018.
The Fukushima Prefectural Government plans to take advantage of the 2020 Games to dispel misinformation about the safety of food produced in the prefecture, home to Tokyo Electric Power Company Holdings Inc.’s Fukushima No. 1 nuclear power plant, where triple reactor meltdowns occurred due to damage from the March 2011 earthquake and tsunami.
In May this year, Fukushima Gov. Masao Uchibori declared that Fukushima aims to rank top among the country’s 47 prefectures in terms of the number of producers with GAP certificates. At present, there are nine GAP-certified producers in the prefecture.
By supplying locally produced food for the games, the prefecture hopes to promote the Fukushima brand in and outside Japan.
The prefectural government is now actively holding seminars to inform farmers and agricultural cooperative officials about the advantages of gaining GAP certification.
A company that operates a fruit farm producing persimmons, peaches and apples in the Fukushima city of Aizuwakamatsu won the JGAP certificate in January.
The process involved preparation of daily work reports and other documents. The costs, including expenses for pesticide storage facilities, were high, according to the firm.
Still, Mitsuhiro Saito, 60, president of the company, said, “The acquisition of the certificate helped boost our awareness about the importance of maintaining a clean environment and labor safety.”
But his farm may face a shortage of fruits for regular sales if products are supplied for the 2020 Games.
Saito now believes that it would be better for his farm to supply products for the Olympics and Paralympics only if inventories are enough, rather than placing absolute priority on the Games and creating problems for regular customers.
Ethical Foundations of Radiological Protection
“The economic and societal factors of the population living in contaminated territories are not the same as the ones of the other parts of the country.”
It even applies to antinuclear activists. Immediately after 311 the priority for the Fukushima activists was the evacuation of the Fukushima children whereas the priority for the other Japanese antinuclear activists was to keep all Japan’s nuke plants from being restarted.
Sadly at national level the second priority prevailed over the first priority, and no measures were in the end taken to evacuate or to protect the Fukushima children from continuous radiation exposure nor from prolonged internal exposure thru local foods.
“..Regarding existing exposure situations after a large-scale nuclear accident, the economic and societal factors of the population living in contaminated territories are not the same as the ones of the other parts of the country. For example, the former want to sell their agricultural production and the later avoids internal contamination….”
“…ICRP recognize that the assessment of beneficence and non-maleficence is a key challenge but has nothing else to propose than recommending, “that such an assessment [should] be transparent about what was included, recognise disagreements where they arise, and go beyond a simple balancing of direct health impacts against economic costs.” ICRP provides no example of good practice arising from these recommendations that are rarely implemented….”
“…Moreover some categories of people are more sensitive to radiations than others. It is particularly the case of children and infants. Justice would mean a better protection with lower limits for them. This is a strong request from families living around the Fukushima dai-ichi nuclear power plant. Some of them evacuated without any support in order to protect their children.
Similarly, individuals are not all equal in terms of genetic heritage and part of this population of hypersensitivity to the adverse effects of radiation (1 to 3% are heterozygous for ataxia telangiectasia). The radiation protection system cannot be built to protect the majority of citizens, but all citizens…..”
“…CRP does not address this issue of individual health in its draft report. How can it expect to answer to the demands of the populations and be understood by them?
“Intergenerational justice has been addressed by the Commission for the management of radioactive waste […]. The Commission introduces responsibilities towards future generations in terms of providing the means to deal with their protection”. Justice could also be extended spatial consideration by forbidding the export of radioactive waste to foreign countries that did not benefit from the electricity production.
Implementation of radiological protection requires democracy to avoid abuses. Nevertheless, democracy is not considered as a core ethical value by ICRP….”
“…ACRO strongly supports the implementation of these three procedural values and considers that they should be implemented from the justification stage. This is not mentioned in the draft report, although it is a requirement the Aarhus convention for environmental issues. This should be extended to radiological protection….”
“…Most of citizen living around the Fukushima dai-ichi nuclear power plant still do not trust authorities. “Accountability” and “transparency” have being ignored by Japanese authorities. The arbitrary evacuation limit of 20 mSv/y has never been explained nor justified. People refusing this limit might have no other choice than remaining in contaminated territories due to economical constrains.
It is a pity that the ICRP has never tried to grasp the situation in contaminated territories as whole and has limited its so-called “dialogues” to a limited number of people that agrees with the Commission. It would have learned much more about the consequences of its recommendations in talking to all categories of people.
As conclusion, ACRO considers that studying the ethical basis of the radiological protection is a necessity but it is not achieved in the present draft report. It should be submitted to various stakeholders and discussed by other means than a simple public consultation on the Internet….”
Robotic Probe Has “Confirmed” Lumps that “Could Be” Fuel Debris in the No.3 Reactor…
Japan’s industry minister says the government hopes to have a policy in place by around September on how to remove melted fuel from the No.3 reactor of the disabled Fukushima Daiichi nuclear power plant.
Hiroshige Seko told reporters on Tuesday that a robotic probe has confirmed lumps that could be fuel debris in the No.3 reactor, giving researchers valuable information.
Seko said he hopes a policy on how to remove the debris can be formulated, based on an analysis and assessment of the probe’s findings.
During the survey last week, a submersible robot found lumps below the reactor pressure vessel and at the bottom of the containment vessel.
It’s the first time a probe has identified what could be a mixture of melted nuclear fuel and broken metal parts lodged inside a reactor container.
Removing the fuel debris would require the use of remote-controlled robots. It is considered the most challenging step in the process to decommission the reactor.
The industry minister suggested that the government plans to honor the existing timetable for decommissioning.
The plan calls for setting specific methods for removing fuel debris by the first half of 2018, so the actual work can begin by 2021.
Deposits in reactor likely to be fuel debris?
The operator of the damaged Fukushima Daiichi nuclear power plant released video footage on Monday of what is likely to be melted fuel debris.
Tokyo Electric Power Company, or TEPCO, found the solidified lumps during a robot inspection of the containment vessel of Fukushima’s wrecked No. 3 reactor. The 3-day survey ended on Saturday.
TEPCO had earlier only made public still images from the probe. The 4-minute video shows black or grey lumps hanging down close to a structure just below the reactor.
The lava-like lumps are piled in layers, a phenomenon unknown before the accident.
TEPCO officials say the debris is probably melted nuclear fuel mixed with broken reactor parts.
In addition to metal scaffolding and other structural components, rocks and sand-like sediment can be seen getting stirred up by the movement of the robot.
The government and TEPCO plan further analysis of the footage in order to determine methods for removing the debris.
https://www3.nhk.or.jp/nhkworld/en/news/20170724_27/
How Much Fuel Was in Fukushima Daiichi Unit 3 Reactor?
“Basically, at Daiichi Unit 3 TEPCO has misplaced 50 plus tons of reactor fuel that was “enriched” with plutonium and now were are being encouraged to think that shards of melted-fuel debris represent the entirety of the missing reactor core….a core that weighed more than a school bus….”
Via Majia’s Blog:
I’ve followed the Fukushima Daiichi disaster so closely for so long that I was surprised to discover this morning that I really don’t know exactly how much fuel was in reactor 3.
I have the data on fuel contained in the spent fuel pools, but NOT the data on fuel in the REACTOR CORES.
Below find the spent fuel pool data:
TEPCO. Integrity Inspection of Dry Storage Casks and Spent Fuels at Fukushima Daiichi Nuclear Power Station (16 November 2010), http://www.nirs.org/reactorwatch/accidents/6-1_powerpoint.pdf
[PARAPHRASING] The total spent uranium fuel inventory at Daiichi in March 2010 was reported as 1,760 tons. The 2010 report asserts that approximately 700 spent fuel assemblies are generated every year. The report specifies that Daiichi’s 3,450 assemblies are stored in each of the six reactor’s spent fuel pools. The common spent fuel pool contains 6291 assemblies. The amount of MOX fuel stored at the plant has not been reported.
SO, 700 spent fuel assemblies were generated at Daiichi each year. There were 6 reactors at Daiichi, although not all were operational at time of earthquake. Assuming they were operational, can we infer that each reactor core contained approximately 100 assemblies?
That estimate is supported by the US Nuclear Regulatory Commission’s information on fuel assemblies found here, which suggests a reactor may contain up to 200 assemblies, with each assembly containing 200 or more rods:
US NRC (2017, April 10). Fuel assembly (fuel bundle, fuel element). https://www.nrc.gov/reading-rm/basic-ref/glossary/fuel-assembly-fuel-bundle-fuel-element.html
A structured group of fuel rods (long, slender, metal tubes containing pellets of fissionable material, which provide fuel for nuclear reactors). Depending on the design, each reactor vessel may have dozens of fuel assemblies (also known as fuel bundles), each of which may contain 200 or more fuel rods.
The website titled Nuclear Power Net, described as non-profit and founded by nuclear engineers, suggests a typical reactor contains 157 fuel assemblies but those are composed of over 45,000 fuel rods (which is more than 200 in each assembly):
Nuclear Power Net (no date). http://www.nuclear-power.net/nuclear-power-plant/nuclear-fuel/
An 1100 MWe (3300 MWth) nuclear core may contain 157 fuel assemblies composed of over 45,000 fuel rods and some 15 million fuel pellets. Generally, a common fuel assembly contain energy for approximately 4 years of operation at full power. Once loaded, fuel stays in the core for 4 years depending on the design of the operating cycle. During these 4 years the reactor core have to be refueled.
During refueling, every 12 to 18 months, some of the fuel – usually one third or one quarter of the core – is removed to spent fuel pool, while the remainder is rearranged to a location in the core better suited to its remaining level of enrichment. The removed fuel (one third or one quarter of the core, i.e. 40 assemblies) has to be replaced by a fresh fuel assemblies.
The variation in data is puzzling but I think we can move forward assuming that there were approximately 100 fuel assemblies in each reactor.
A typical fuel assembly for a Pressured Water Reactor (PWR) “stands between four and five metres high, is about 20 cm across and weighs about half a tonne” according to the World Nuclear Association (http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/conversion-enrichment-and-fabrication/fuel-fabrication.aspx).
USING THESE DATA POINTS, I can infer that Unit 3’s reactor core contained approximately 50-75 tons of fuel. Does that sound roughly correct? A ton is 2,000 pounds so 50 tons of fuel is 100,000 pounds. For metric users, that converts into 45359.237 kilograms.
Why is it so important that I determine how much fuel was in reactor 3?
The reason lies in the media representations of TEPCO’s robotic probe, Little Sunfish, which allegedly has (likely) located unit 3’s missing reactor fuel, illustrated in the media as “rocks on the floor”:
Kohei Tomida (July 23, 2017). Melted nuke fuel images show struggle facing Fukushima plant. The Asahi Shimbun, http://www.asahi.com/ajw/articles/AJ201707230012.html
In particular, what is believed to be nuclear fuel debris is scattered in the form of rocks in the area directly beneath the pressure vessel.
My point is not to deny that these found rocks might be nuclear fuel debris. Rather, my point is that these shards of melted fuel and debris can hardly be construed as representing the entirety of the fuel.
Put otherwise, there is no compelling evidence that TEPCO has located the majority of fuel that was contained in Unit 3.
I decided to search my notes, books, and the web validated statistics on how much fuel each reactor contained. I was struck by how little information is available about the missing fuel and the sanitized accounts of what happened at unit 3, the one running MOX fuel.
Basically, at Daiichi Unit 3 TEPCO has misplaced 50 plus tons of reactor fuel that was “enriched” with plutonium and now were are being encouraged to think that shards of melted-fuel debris represent the entirety of the missing reactor core….a core that weighed more than a school bus….
http://majiasblog.blogspot.fr/2017/07/how-much-fuel-was-in-fukushima-daiichi.html
High School Girls Used to Promote a Beach in Fukushima
They used high school girls to promote a beach in Fukushima. The same way that they were using highschool kids to pick up trash along the Joban Expressway….
“Photo Journal: Long-awaited laughter”
High school students in the garb of Hawaiian hula dancers play in the waves at the Usuiso seaside resort in Iwaki, Fukushima Prefecture, after the beach opened for the first time in seven years on July 15, 2017. The resort was heavily hit by the 2011 tsunami, which took the lives of 115 residents and destroyed close to 90 percent of homes in the district. However, the resort finally reopened its stretches of white sands to families on Saturday, with lively hula performances by local high school girls. (Mainichi) https://mainichi.jp/english/articles/20170715/p2a/00m/0na/014000c
Likely Melted Fuel Heap Found Inside Fukushima Daiichi’s Reactor 3 Shows Future Removing Difficulties
Underwater robot finds likely melted fuel heap inside Fukushima reactor
This image captured by an underwater robot provided by International Research Institute for Nuclear Decommissioning on Saturday, July 22, 2017 shows heaps of solidified lava-like rocks believed to be nuclear fuel.
TOKYO (AP) — Images captured by an underwater robot showed massive deposits believed to be melted nuclear fuel covering the floor of a damaged reactor at Japan’s crippled Fukushima nuclear plant.
The robot found large amounts of solidified lava-like rocks and lumps in layers as thick as 1 meter on the bottom inside of a main structure called the pedestal that sits underneath the core inside the primary containment vessel of Fukushima’s Unit 3 reactor, said the plant’s operator, Tokyo Electric Power Co.
On Friday, the robot spotted suspected debris of melted fuel for the first time since the 2011 earthquake and tsunami caused multiple meltdowns and destroyed the plant. The three-day probe of Unit 3 ended Saturday.
Locating and analyzing the fuel debris and damage in each of the plant’s three wrecked reactors is crucial for decommissioning the plant. The search for melted fuel in the two other reactors has so far been unsuccessful because of damage and extremely high radiation levels.
During this week’s probe, cameras mounted on the robot showed extensive damage caused by the core meltdown, with fuel debris mixed with broken reactor parts, suggesting the difficult challenges ahead in the decades-long decommissioning of the destroyed plant.
TEPCO spokesman Takahiro Kimoto said it would take time to analyze the debris in the images to figure out debris removal methods.
http://mainichi.jp/english/articles/20170723/p2g/00m/0dm/033000c
Melted nuke fuel images show struggle facing Fukushima plant
What is believed to be nuclear fuel debris has accumulated at the submerged bottom of the containment vessel in the No. 3 reactor at the Fukushima No. 1 nuclear power plant in an image taken on July 22. Part of the collapsed metal scaffolding is seen at back right.
Images captured on July 22 of solidified nuclear fuel debris at the bottom of a containment vessel of the crippled Fukushima No. 1 nuclear power plant show the enormity of decommissioning of the facility.
Plant operator Tokyo Electric Power Co. said it will closely study the images from the No. 3 reactor’s containment vessel to determine the spread and amount of nuclear fuel debris.
After analysis, TEPCO will decide on a policy to retrieve the fuel debris.
The government and TEPCO plan to start the retrieval process in one of the three crippled reactors at the plant from 2021.
It will be a formidable task, given that a method of recovering debris that is stuck to the floor has yet to be considered.
The recent images were taken by a submersible robot, which was sent into the containment vessel on July 19, 21 and 22.
The No. 3 reactor’s containment vessel is filled with water to a depth of 6.4 meters.
On the final day, the remote-controlled robot was dispatched to the deepest part of the containment vessel.
The images showed that pieces that fell from the structure and deposited material accumulated to a height of about 1 meters at the bottom of the containment vessel.
In particular, what is believed to be nuclear fuel debris is scattered in the form of rocks in the area directly beneath the pressure vessel.
The latest investigation has confirmed TEPCO’s assumption made through analyses that most of the reactor’s nuclear fuel melted through the pressure vessel and accumulated at the bottom of the containment vessel.
It also discovered that the nuclear fuel debris has spread throughout the containment vessel.
The images marked the first confirmation through a robot probe of a large amount of nuclear debris in any of the embattled No. 1 through No. 3 reactors.
Japan Pictures Likely Show Melted Fukushima Fuel for First Time
New images show what is likely to be melted nuclear fuel hanging from inside one of Japan’s wrecked Fukushima reactors, a potential milestone in the cleanup of one of the worst atomic disasters in history.
Tokyo Electric Power Co. Holdings Inc., Japan’s biggest utility, released images on Friday showing a hardened black, grey and orange substance that dripped from the bottom of the No. 3 reactor pressure vessel at Fukushima, which is likely to contain melted fuel, according to Takahiro Kimoto, an official at the company. The company sent a Toshiba-designed robot, which can swim and resembles a submarine, to explore the inside of the reactor for the first time on July 19.
“Never before have we taken such clear pictures of what could be melted fuel,” Kimoto said at a press briefing that began at 9 p.m. Friday in Tokyo, noting that it would take time to analyze and confirm whether it is actually fuel. “We believe that the fuel melted and mixed with the metal directly underneath it. And it is highly likely that we have filmed that on Friday.”
Pictures taken on July 21 inside of Fukushima reactor. Source: Tokyo Electric Power Co. Holdings Inc.
If confirmed, the substance — which has the appearance of icicles — would be the first discovery of the fuel that melted during the triple reactor accident at Fukushima six years ago. For Tokyo Electric, which bears most of the clean-up costs, the discovery would help the utility design a way to remove the highly-radioactive material.
The robot, which is about 30 centimeters (12 inches) long, will search for melted fuel at the bottom of the reactor on Saturday. It is possible that the company will take more pictures of what could be melted fuel spread across the floor and lower levels, according to Tokyo Electric’s Kimoto. Fuel from a nuclear meltdown is known as corium, which is a mixture of the atomic fuel rods and other structural materials.
Early Signs
“It is important to know the exact locations and the physical, chemical, radiological forms of the corium to develop the necessary engineering defueling plans for the safe removal of the radioactive materials,” said Lake Barrett, a former official at the U.S. Nuclear Regulatory Commission who was involved with the cleanup at the Three Mile Island nuclear power plant in the U.S. “The recent investigation results are significant early signs of progress on the long road ahead.”
Because of the high radioactivity levels inside the reactor, only specially designed robots can probe the unit. And the unprecedented nature of the Fukushima disaster means that Tepco, as the utility is known, is pinning its efforts on technology not yet invented to get the melted fuel out of the reactors.
Removal Plans
The company aims to decide on the procedure to remove the melted fuel from each unit as soon as this summer. And it will confirm the procedure for the first reactor during the fiscal year ending March 2019, with fuel removal slated to begin in 2021.
Decommissioning the reactors will cost 8 trillion yen ($72 billion), according to an estimate in December from the Ministry of Economy, Trade and Industry. Removing the fuel is one of the most important steps in a cleanup that may take as long as 40 years.
Similar to the latest findings on Friday, Tepco took photographs in January of what appeared to be black residue covering a grate under the Fukushima Dai-Ichi No. 2 reactor, which was speculated to have been melted fuel. However, a follow-up survey by another Toshiba-designed robot in February failed to confirm the location of any melted fuel in the reactor after it got stuck in debris.
A robot designed by Hitachi-GE Nuclear Energy Ltd. also failed to find any melted fuel during its probe of the No. 1 reactor in March.
The significance of Friday’s finding “might be evidence that the robots used by Tepco can now deal with the higher radiation levels, at least for periods of time that allow them to search parts of the reactor that are more likely to contain fuel debris,” M.V. Ramana, professor at the Liu Institute for Global Issues at the University of British Columbia, said by email.
“If some of these fragments can be brought out of the reactor and studied, it would allow nuclear engineers and scientists to better model what happened during the accident.”
Highly likely fuel debris found for 1st time at Fukushima plant
The operator of the crippled Fukushima Daiichi nuclear complex said Friday it found material likely to be nuclear fuel debris in its latest probe at one of the plant’s three damaged reactors.
It is the first time material “highly likely” to be melted fuel has been spotted inside a reactor at the complex since the 2011 massive earthquake and tsunami crippled the Fukushima nuclear power plant, the operator Tokyo Electric Power Company Holdings Inc. said.
Material found near the bottom of the damaged pressure vessel of the No. 3 reactor is likely to have been formed by fuel that melted, Takahiro Kimoto, a Tepco spokesman, said at a press conference.
“We think that the fuel inside the vessel melted and caused structures to fall from above,” Kimoto said.
Tepco is trying to confirm the condition of fuel debris inside the No. 3 reactor with a robot to start work on removing the debris in 2021, one of the most difficult stages of the decommissioning project that is expected to take at least 30 to 40 years to complete.
Decommissioning work has progressed slowly as radiation levels inside the reactors remain extremely high.
Water around 6.4 meters deep, which was injected into the reactor to cool fuel debris inside, has accumulated at the bottom of the containment vessel.
Tepco used a cylinder-shaped underwater robot with a diameter of 13 centimeters, dubbed “little sunfish.”
In Friday’s probe, following one on Wednesday, the robot looked inside the reactor’s containment vessel housing the pressure vessel, which is partially filled with contaminated water.
Another round of probe is scheduled on Saturday, where the remote-controlled robot is expected to swim deeper to the bottom of the containment vessel to locate a chunk of melted fuel that is believed to lie.
On March 11, 2011, a huge tsunami hit the six-reactor plant, located on ground 10 meters above sea level, and flooded power supply facilities.
Reactor cooling systems were crippled and the Nos. 1-3 units suffered fuel meltdowns in the world’s worst nuclear disaster since the 1986 Chernobyl crisis.
From January to March, Tepco conducted robot surveys including sending a self-propelled robot into the Nos. 1 and 2 reactors, where water levels are lower than the No. 3 reactor, but they failed to ascertain the condition of fuel debris.
30Bq/kg of Strontium 90 in Sea Breams in the Sea 2km from the Kido River
TEPCO released a document stating that 30Bq/kg of Strontium 90 was found in sea breams in the sea 2km from the Kido river (near J-Village).
Click to access fish03_170713-j.pdf
Fuel debris possibly found in Fukushima Daiichi’s Reactor 3
Images show possible fuel debris
Engineers at the Fukushima Daiichi nuclear power plant are working to scrap the facility’s damaged reactors. For the first time, they’ve found what’s likely to be fuel debris in one of them.
The engineers have been trying to locate molten fuel in the No.3 reactor. The fuel is thought to have melted and fallen to the bottom of the containment vessel.
They lowered a submersible robot into the 6-meter-deep cooling water in the vessel. The image sent back by the robot shows an orange substance on a device that operates the fuel control rods. Objects shaped like icicles are also visible.
The engineers plan to use the robot to look for fuel debris at the bottom of the containment vessel.
Removing the molten fuel from the reactors is the biggest hurdle to decommissioning them.
https://www3.nhk.or.jp/nhkworld/en/news/20170722_04/
TEPCO surveys bottom of reactor containment vessel
The operator of the Fukushima Daiichi nuclear power plant has carried out another robotic survey in one of the damaged reactors. The probe is meant to confirm the existence and status of fuel debris consisting of molten fuel and reactor parts.
Officials of Tokyo Electric Power Company, or TEPCO, say the probe took place at the bottom of the containment vessel in the No.3 reactor on Saturday. The vessel’s bottom is thought to hold much fuel debris.
TEPCO used a robot designed to move through cooling water in the vessel.
The survey follows Friday’s release of photographs taken during the previous underwater robotic probe of the same vessel. The robot did not reach the vessel’s bottom during the first probe.
The images show rock-like lumps located near walls of a reactor-supporting structure and various other parts of the vessel.
TEPCO officials say it is very likely the lumps are fuel debris created after nuclear fuel in the reactor melted, mixed with reactor parts, and fell. If confirmed, this would be the first time fuel debris has been found in the No.3 reactor.
Robotic probes have so far failed to provide clear evidence showing the existence and status of fuel debris in other 2 damaged reactors.
Removing the fuel debris is one of the major hurdles to decommissioning the reactors which continues to emit extremely high levels of radiation.
https://www3.nhk.or.jp/nhkworld/en/news/20170722_22/
“Possible” melted fuel seen for first time at Fukushima plant
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