Fukushima’s decommissioning delays, challenges and unknowns remain roadblocks to cleanup — Beyond Nuclear

” Six and a half years after the Fukushima Daiichi triple meltdown, Japan’s government, the nuclear regulator and Tokyo Electric Power Company’s (TEPCO) most rudimentary plan of attack for recovery from radioactive catastrophe is delayed again. The first steps of decommissioning cannot legitimately begin until undamaged but highly radioactive “spent” fuel assemblies are removed from vulnerable reactor storage ponds, sufficiently cooled and re-contained in qualified dry storage casks.  Then, there are the three melted fuel cores that still must be located, retrieved and somehow re-contained. Where all of the massive radioactive contamination will go is a mystery.  In fact, there are an alarming number of challenges, continuing delays and unknowns that remain before securing the destroyed nuclear power station site and halting the ongoing release of radioactivity to the land, water and air.

Among the most immediate concerns is the management of 1007 highly radioactive and thermally hot irradiated nuclear fuel assemblies still in the two cooling pools perched atop the destroyed Units 1 and 2 outside of any containment structure. Each of the site’s six-units has an elevated nuclear waste storage pond. The site has a large common pool located near Unit 4. The government recently admitted that previously unknown, possibly undisclosed, damage in these irradiated fuel storage ponds and radioactive contamination has again delayed the plan to move the dangerous fuel assemblies by at least another three years, now 2023. Unit 3 remains on schedule in 2018 to begin the two-year transfer of 514 irradiated fuel assemblies from its rooftop storage pool to a jam-packed common onsite pool located at ground level. This common pool and its massive radioactive inventory requires reliable cooling power.  Unit 4 completed a three-year project to transfer its irradiated fuel into the common pool in 2014. The common pool now has 6,726 irrradiated fuel assemblies with a maximum design capacity of 6,840. As this common pool is already densely packed, it is ever more critical that Japan expedite the transfer of the sufficiently cooled irradiated nuclear fuel into qualified, individualized dry storage casks that can passively cool the hot nuclear waste without the need for water and electrical power. Currently, only 1,412 irradiated assemblies have been secured in onsite dry cask storage. These dry casks further need to be hardened against another natural disaster and possible terrorism.

The recurring delays at securing the irradiated fuel currently in wet pool storage (individual units to the common pool) and then into scientifically-qualified and hardened dry cask storage systems raises concern for public health, safety and the environment given the prospect of another large nearby earthquake causing a loss of cooling with the risk of a nuclear waste fire and radioactive releases. A 6.9 magnitude offshore earthquake on November 21, 2016 caused a temporary loss of cooling to wet storage systems at Fukushima Daiichi. Significant earthquakes of 6.0 to 6.9 magnitude occur in Japan on average 17 times per year, roughly one-tenth of all large earthquakes in the world. More severe earthquakes must be anticipated. The loss of cooling power and water to some or all of the more than 11,577 hot nuclear waste assemblies onsite outside of containment remains a significant public health, safety and environmental concern.

Japan is still technologically conceptualizing the “most challenging part” of Fukushima Daiichi’s decommissioning and the recovery of three missing melted reactor cores if and when they can be located. The unprecedented operation has now been delayed until 2019.  A viable technology for scooping up melted nuclear fuel does not yet exist. Re-containment and removal of the melted fuel cores is key to addressing the ongoing massive buildup of radioactive water now estimated at 800,000 tons that is being stored in growing onsite tank farms.  Groundwater flowing down into the reactor wreckage must be constantly pumped out, partially filtered of radioactivity and stored onsite in the large tanks. The tank farms themselves represent an additional environmental threat in the event of another severe earthquake that could rupture the structures with a radioactive flood into the ocean. ”

by Beyond Nuclear

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Elimination of Fukushima evacuees from list slammed — The Asahi Shimbun

” The central government has made a large number of people who voluntarily fled the Fukushima area after the 2011 nuclear disaster disappear by cutting them from official lists of evacuees.

Critics are now condemning the move, which went into effect last April, saying it prevents government officials from fully grasping the picture of all who remain displaced to evaluate their future needs.

“Accurate data on Fukushima evacuees is essential in gaining a better understanding of their current circumstances and crafting measures to address their problems,” said Shun Harada, a sociology researcher at Rikkyo University in Tokyo, who contributes as an editor for an information publication for evacuees living in Saitama Prefecture.

“When only smaller than the real numbers are made available, difficulties facing evacuees could be underestimated and could result in terminating support programs for them,” he complained.

As of July, 89,751 evacuees were living across Japan after fleeing from the nuclear disaster, down by 29,412 from the March tally.

In April, the central government opted to cut “voluntary” evacuees who fled their homes due to fears of radiation despite being from outside the evacuation zone.

It came after the official program to provide free housing to the voluntary evacuees was stopped at the end of March, which was designed to facilitate a prompt return to their hometowns in Fukushima Prefecture. People from the evacuation zone are still eligible to the free housing program.

The central government’s Reconstruction Agency, set up to oversee rebuilding efforts in Japan’s northeastern region after the 2011 Great East Japan Earthquake, tsunami and nuclear disaster, releases the number of evacuees each month, based on figures compiled by local authorities.

The 29,412 drop in the number of official evacuees between March and July includes 15,709 in Fukushima Prefecture, 6,873 in Miyagi Prefecture, 2,798 in Iwate Prefecture, 780 in Tokyo, 772 in Kanagawa Prefecture and 577 in Saitama Prefecture.

Before the change in housing policy, agency statistics showed a monthly decrease in evacuee numbers of between 3,000 and 4,000 in the several months leading up to the end of March.

But the drop in numbers increased dramatically to 9,493 between March and April and 12,412 between April and May.

Kanagawa and Saitama prefectural officials say voluntary evacuees were responsible for most of the declines in their jurisdictions.

A large number of them are believed to be living in the same housing as before but are now paying their own rent.

A 43-year-old woman who has been evacuating in Saitama Prefecture since fleeing from Iwaki, Fukushima Prefecture, with three other family members said she is angered by the central government’s treatment.

“We cannot return to Fukushima Prefecture due to fears of the effects of radiation,” she said. “I feel like I have been abandoned by the state by being denied evacuee status.”

An official with the Tokyo-based Japan Civil Network for Disaster Relief in East Japan, a private entity that functions as a liaison unit for a nationwide network of groups supporting victims of the disaster six years ago stressed the need for local authorities to have an accurate understanding of the circumstances surrounding evacuees.

“Of the evacuees, the elderly and single-parent households tend to be left in isolation and many of them are likely to become qualified to receive public assistance in the near future,” the official said. “Local officials need to know they are evacuees (from Fukushima).”

The official added that it will become difficult for support groups to extend their help if voluntary evacuees are taken out of the official tally.

But the Reconstruction Agency said it will not reconsider the definition of evacuees. ”

by Shigeo Hirai, The Asahi Shimbun

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Work to finish ice wall at crippled plant to begin — NHK World

” The operator of the crippled Fukushima Daiichi nuclear plant will begin the final phase of creating an underground ice wall on Tuesday.

Tokyo Electric Power Company started the work 17 months ago, with the aim of preventing groundwater from entering reactor buildings and getting contaminated with radioactive substances.

The 1.5-kilometer ice barrier is deemed a key step to curb the buildup of tainted water at the plant.

The soil is frozen by sending liquid at minus 30 degrees Celsius into pipes buried around the buildings. But the utility has left a 7-meter section unfrozen, fearing the sudden fall in groundwater levels around the buildings.

There were concerns that the difference of water levels in and outside the reactor buildings would cause tainted water inside to leak out.

But last Tuesday, the Nuclear Regulation Authority said safety measures are ready and gave its approval to freeze of the final section.

Officials of the utility say they will carefully monitor the freezing process of the remaining section.

They say it may take longer to fully freeze than other areas, because the flow of groundwater has been concentrated in that section.

The officials expect that the wall, when completed, will reduce the inflow of groundwater to the buildings from 140 tons a day to less than 100 tons. ”

by NHK World

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Excessive radiation detected in vehicles removed from Fukushima nuke plant — The Mainichi

” Radiation topping the government-set limit has been detected in about 190 vehicles removed from the premises of the Fukushima No. 1 Nuclear Power Plant after the outbreak of the nuclear crisis, it has been learned.

Some of the cars were sold on the used-car market while two others remain unaccounted for, according to plant operator Tokyo Electric Power Co. (TEPCO).

Approximately 1,700 vehicles were parked on the premises of the power station when the nuclear crisis broke out after it was hit by the powerful earthquake and tsunami on March 11, 2011, TEPCO officials said. Of those, about 600 were owned by employees of TEPCO or companies contracted by the utility. Over a 12-day period until radiation screenings began on March 23 of that year, people could drive the vehicles out of the premises of the plant without checks.

The Economy, Trade and Industry Ministry instructed TEPCO in February 2012 to conduct a follow-up probe into the use of these vehicles for fear that next owners of those cars could be exposed to radiation without knowing that the vehicles were contaminated.

The power company conducted a survey on employees and contracted companies that parked their cars on the plant’s premises at the time of the accident, and confirmed that about 460 vehicles were brought out of the plant by April 2015. It was learned that radiation levels for around 190 of the vehicles exceeded government-set safety standards, and some of them were found contaminated with radiation nearly 10 times over the limit. All the vehicles whose radiation levels exceeded the limit were collected from their owners and are now stored on TEPCO’s premises situated in a Fukushima Prefecture area designated as a highly contaminated “difficult-to-return zone.”

TEPCO is considering how to dispose of these heavily contaminated vehicles, with an official saying, “We’d like to continue searching for two vehicles that remain unaccounted for and respond to the situation in an appropriate manner.” ”

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Radioactively-hot particles detected in dusts and soils from Northern Japan by combination of gamma spectrometry, autoradiography, and SEM/EDS analysis — Marco Kaltofen, Arnie Gundersen, ScienceDirect

“Abstract

After the March 11, 2011, nuclear reactor meltdowns at Fukushima Dai-ichi, 180 samples of Japanese particulate matter (dusts and surface soils) and 235 similar U.S. and Canadian samples were collected and analyzed sequentially by gamma spectrometry, autoradiography, and scanning electron microscopy with energy dispersive X-ray analysis. Samples were collected and analyzed over a five-year period, from 2011 to 2016. Detectable levels of 134Cs and 137Cs were found in 142 of 180 (80%) Japanese particulate matter samples. The median radio-cesium specific activity of Japanese particulate samples was 3.2 kBq kg− 1 ± 1.8 kBq kg− 1, and the mean was 25.7 kBq kg− 1(σ = 72 kBq kg− 1). The U.S. and Canadian mean and median radio‑cesium activity levels were < 0.03 kBq kg− 1. U.S. and Canadian samples had detectable 134Cs and 137Cs in one dust sample out of 32 collected, and four soils out of 74. The maximum US/Canada radio-cesium particulate matter activity was 0.30 ± 0.10 kBq kg− 1. The mean in Japan was skewed upward due to nine of the 180 (5%) samples with activities > 250 kBq kg− 1. This skewness was present in both the 2011 and 2016 sample sets.

300 individual radioactively-hot particles were identified in samples from Japan; composed of 1% or more of the elements cesium, americium, radium, polonium, thorium, tellurium, or strontium. Some particles reached specific activities in the MBq μg− 1 level and higher. No cesium-containing hot particles were found in the U.S. sample set. Only naturally-occurring radionuclides were found in particles from the U.S. background samples. Some of the hot particles detected in this study could cause significant radiation exposures to individuals if inhaled. Exposure models ignoring these isolated hot particles would potentially understate human radiation dose. ”

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Japanese robot probes the radioactive water at Fukushima’s nuclear reactor to find melted fuel — Daily Mail

” A Japanese robot has begun probing the radioactive water at Fukushima’s nuclear reactor.

The marine robot, nicknamed the ‘little sunfish’, is on a mission to study structural damage and find fuel inside the three reactors of the devastated plant.

Experts said remote-controlled bots are key to finding fuel at the dangerous site, which has likely melted and been submerged by highly radioactive water.

The probe – about the size of a loaf of bread – is equipped with lights, manoeuvres using tail propellers and collects data using two cameras and a dosimeter radiation detector.

Plant operators chose to send the robot inside the containment vessel of the No. 3 reactor because it has highest known water levels out of the the three reactors.

The robot entered the structure at 6.30am JST (10.30 BST, 5.30 ET) through a pipe connected to the containment vessel.

The marine machine, which was attached to cables, then swam to the area just below the reactor pressure vessel inside to take images.

New images taken by the robot show how parts of the system, including the control rod, have been damaged by radiation.

On Friday, the robot will continue its travels to the bottom of the containment vessels, where melted fuel deposits are believed to have accumulated.

In 2011, a 10-metre-high tsunami that killed nearly 19,000 people crashed into Japan’s Fukushima nuclear power plant, leading to several meltdowns.

Five years after the disaster, researchers are still struggling to clean up the highly dangerous radioactive materials in water of the wasting reactors.

It’s estimated that plant officials have only located 10 per cent of the waste fuel left behind after the nuclear meltdowns.

And the damaged plant is believed to be leaking small amounts of the radioactive waste into the Pacific Ocean, which could be travelling as far as the west cost of the US.

Researchers are now pinning their hopes on the remote-controlled sunfish robot to locate the lost fuel in order to work out the safest way to remove it.

During a demonstration of the device at a test facility near Tokyo last month, the probe slowly slid down from a rail and moved across the water.

A team operated it remotely, with one guiding the robot while another adjusted a cable that transmits data and serves as its lifeline.

Japan hopes to locate and start removing fuel from the reactors after Tokyo’s 2020 Olympics.

In earlier operations, snake and scorpion-shaped robots became stuck inside two reactors.

The scorpion robot’s crawling function failed and it was left inside the plant’s Unit 2 containment vessel.

The other, designed for cleaning debris for the ‘scorpion’ probe, was called back after two hours when two of its cameras stopped working after its total radiation exposure reached 1,000 Sievert – a level that would kill a human within seconds.

The plan had been to use the robot for 10 hours at an exposure level of 100 Sievert per hour.

The swimming robot shown was co-developed by electronics and energy giant Toshiba and the government’s International Research Institute for Nuclear Decommissioning. “

by Daisy Dunne, Mail Online and Associated Press

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