Earthquake offshore of Japan shakes crippled Fukushima Nuclear Power Plant — Temblor

” At 9:11 a.m. local time today, a M=5.8 earthquake struck offshore of Japan, near the Fukushima Nuclear Reactor, which was crippled in the M=9 Tohoku earthquake in 2011. Fortunately this quake was not large enough to cause any new damage to the reactor, which is expected to take at least four decades to dismantle. Two of the reasons why no damage occurred is because the quake was offshore and at a depth of 35 km, meaning only light shaking was felt in populated centers of Iwaki (Pop: 357,000) and Fukushima (Pop: 294,000). The USGS PAGER system estimates that should there be any economic losses, they will remain extremely minimal.

Japan is one of the most seismically active countries on earth. Just off the eastern coast of the country are two subduction zones. In the southern part of the country is the Nansei-Shoto (Ryukyu) Trench, where there Philippine Sea plate subducts beneath the Eurasian Plate at rates varying from 47-61 mm/yr. To the north, is the Japan Trench, where the Pacific Plate subducts beneath the North American Plate at rates as high as 90 mm/yr (See USGS map below). What is also evident in this map is that northern Japan is much more seismically active than the southern portion of the country. While much of this can be attributed to aftershocks from the M=9.0 Tohoku earthquake there is still a greater rate of seismicity in the north. Based on the location of today’s M=5.8 earthquake, and its shallowly-dipping thrust focal mechanism, it likely occurred on the subducting slab, making this a late aftershock of the 2011 Tohoku quake.

In terms of the seismic hazard of Japan, there are two schools of thought, which are heavily related to the recent seismicity and convergence rates. Below is a comparison of the Global Earthquake Activity Rate (GEAR) model, which is available in Temblor, and the Japan National Hazard Model. The GEAR model uses seismicity from the last 40 years and global strain rates to forecast the likely earthquake magnitude in your lifetime anywhere on earth, while the Japanese model estimates the likelihood of strong ground shaking. What is immediately evident is that the models are almost opposite one another. The GEAR model sees the lack of earthquakes and slower convergence rates near the Nankai Trough as an indication of lower seismic potential, whereas the Japanese model interprets it as an increased likelihood of a large magnitude earthquake. While it is entirely possible that a large quake could strike along the Nankai Trough, it should be pointed out that the Japanese model misses the hazard near the M=9.0 Tohoku earthquake, while the GEAR model shows an extremely high hazard.

Regardless of which model better depicts the seismic hazard of Japan, what is clear is that nearly the entire eastern seaboard is susceptible to seeing M=6.75 earthquakes. This translates into an extremely high awareness among residents. It is because of this that Japan is at the forefront of seismic safety, and often considered the country after which other countries should model their earthquake preparedness. ”

by David Jacobson, Temblor

source with maps of the earthquake

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Japan pictures likely show melted Fukushima fuel for first time — Bloomberg

” 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.”

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.” ”

by Stephen Stapczynski, Bloomberg

source

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

source with photos and video

Minister opposes releasing treated water from Fukushima plant into sea — The Mainichi

According to The Georgia Straight, plans to dump tritium-contaminated waste water into the Pacific Ocean have been cancelled.

The Mainichi: ” TOKYO (Kyodo) — Japan’s disaster reconstruction minister said Friday he is opposed to treated water from the disaster-struck Fukushima Daiichi nuclear power plant being released into the sea, citing the possible repercussions for local fishermen.

Masayoshi Yoshino’s remarks came shortly after a top official from plant operator Tokyo Electric Power Company Holdings Inc. said he is ready to see the tritium-containing water dumped into the sea.

A government panel is still debating how to deal with the water stored in tanks at the plant where three nuclear reactors melted down in the days after a huge earthquake and then tsunami struck the region in 2011.

Tritium is a radioactive substance considered relatively harmless to humans. It remains in the filtered water as it is difficult to separate even after passing through a treatment process. At other nuclear power plants, tritium-containing water is routinely released into the sea after it is diluted.

Yoshino expressed at a news conference his concerns over the potential ramifications of releasing the treated water into the sea, saying there would “certainly be (perception) damage due to unfounded rumors.”

The minister urged those pushing for the release of the water “not to create fresh concerns for fishermen and those running fishing operations in Fukushima Prefecture.” He also asked them “not to drive (fishermen) further towards the edge.”

He was alluding to concerns among local fishermen about the effects on their livelihood if the public perceives fish and other marine products caught off Fukushima to be contaminated.

Takashi Kawamura, chairman of Tepco, said in a recent interview that the decision to discharge the treated water “has already been made.”

After Kawamura’s remarks were widely reported, the utility was forced to make a clarification through a statement on Friday. Tepco said its chairman meant to say there is “no problem (with releasing water containing tritium) according to state guidelines based on scientific and technological standpoints,” and that the decision to release is not yet final.

While the plant operator and the Ministry of Economy, Trade and Industry want to discharge the water, the local fishermen, backed by the minister, are opposed to it.

At the Fukushima plant, water becomes toxic when it is used to cool the damaged reactors. It is treated through a process said to be capable of removing 62 different types of radioactive material, except tritium.

Yoshino said Friday that while he is aware of some scientists’ opinion that the water should be released after it is diluted to permissible levels, he is not in favor of the idea.

“As I am also a native of Fukushima Prefecture, I fully understand the sentiment of the people,” Yoshino said. However, the minister has no authority to decide how the treated water will be disposed.

An ever-increasing amount of water containing tritium is collecting in tanks at the Fukushima plant. As of July 6, approximately 777,000 tons were stored in about 580 tanks.

On March 11, 2011, water inundated 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 to 3 reactors suffered fuel meltdowns in the world’s worst nuclear catastrophe since the 1986 Chernobyl disaster. “

by The Mainichi

source

Fishermen express fury as Fukushima plant set to release radioactive material into ocean — The Telegraph

” Local residents and environmental groups have condemned a plan to release radioactive tritium from the crippled Fukushima nuclear plant into the Pacific Ocean.

Officials of Tokyo Electric Power Co., the operator of the plant, say tritium poses little risk to human health and is quickly diluted by the ocean.

In an interview with local media, Takashi Kawamura, chairman of TEPCO, said: “The decision has already been made.” He added, however, that the utility is waiting for approval from the Japanese government before going ahead with the plan and is seeking the understanding of local residents.

The tritium is building up in water that has been used to cool three reactors that suffered fuel melt-downs after cooling equipment was destroyed in the magnitude 9 earthquake and tsunami that struck north-east Japan in March 2011.

Around 770,000 tons of highly radioactive water is being stored in 580 tanks at the site. Many of the contaminants can be filtered out, but the technology does not presently exist to remove tritium from water.

“This accident happened more than six years ago and the authorities should have been able to devise a way to remove the tritium instead of simply announcing that they are going to dump it into the ocean”, said Aileen Mioko-Smith, an anti-nuclear campaigner with Kyoto-based Green Action Japan.

“They say that it will be safe because the ocean is large so it will be diluted, but that sets a precedent that can be copied, essentially permitting anyone to dump nuclear waste into our seas”, she told The Telegraph.

Fishermen who operate in waters off the plant say any release of radioactive material will devastate an industry that is still struggling to recover from the initial nuclear disaster.

“Releasing [tritium] into the sea will create a new wave of unfounded rumours, making all our efforts for naught”, Kanji Tachiya, head of a local fishing cooperative, told Kyodo News. ”

by Julian Ryall, The Telegraph

source

Nuclear authority chief raps Tepco’s attitude toward Fukushima — The Mainichi

” TOKYO (Kyodo) — The head of Japan’s nuclear safety watchdog on Monday criticized the attitude of Tokyo Electric Power Company Holdings Inc. toward decommissioning of the crisis-hit Fukushima Daiichi nuclear power plant and questioned the company’s ability to resume operation of other reactors.

 “I feel a sense of danger,” Nuclear Regulation Authority Chairman Shunichi Tanaka said during a special meeting with the company’s top management, adding that Tokyo Electric does “not seem to have a will to take initiative” toward decommissioning of the crippled Fukushima Daiichi plant.

Takashi Kawamura, the chairman of the power company known as Tepco, and its president, Tomoaki Kobayakawa, attended the meeting. The authority felt it is necessary to hear from the top executives before it could make a decision on whether to approve Tepco’s plan to resume operation of the Nos. 6 and 7 reactors at its Kashiwazaki-Kariwa plant in Niigata Prefecture.

Tepco filed for state safety assessment of the two reactors in September 2013 to reactivate them, hoping to restore its financial condition as it needed massive funds to pay compensation related to the Fukushima Daiichi disaster, triggered by a huge earthquake and tsunami on March 11, 2011, and to scrap the plant that suffered meltdowns.

The watchdog’s safety screening has found Tepco’s failure to report insufficient earthquake resistance of a facility built to serve as the base to deal with a possible nuclear accident at the Niigata complex although it had acknowledged the insufficiency for three years.

In June, Tepco submitted to the watchdog its revised safety measures for the Kashiwazaki-Kariwa complex.

“An operator lacking will to take initiative does not have the right to resume operation of nuclear reactors,” Tanaka said.

Tepco’s chairman responded by saying, “There are citizens who believe nuclear power is necessary. Operating reactors is our responsibility.”

But he also admitted there is room for only two more years’ worth of space in the tanks to accommodate contaminated water stemming from the Fukushima complex.

At Monday’s meeting, the watchdog asked Tepco’s top management about the company’s safety measures for the Niigata complex on the Sea of Japan coast as well as its safety awareness.

Tanaka said the authority does not view that it received sufficient responses from Tepco at the meeting and requested that the company submit more explanation on its plan to decommission the Fukushima complex and resume operation of the two reactors at the Kashiwazaki-Kariwa plant.

Tanaka plans to conduct on-site checkups at the two reactors of the plant in Niigata, saying, “Tepco, which caused the (Fukushima) accident, is not an ordinary operator.”

The two boiling water reactors at the Niigata plant are the same type as those that suffered core meltdowns at the Fukushima Daiichi complex, and no such reactors have cleared the authority’s safety screening since the Fukushima disaster. “

source