Cleaner robot pulled from Fukushima reactor due to radiation — Beloit Daily News

” TOKYO (AP) — A remote-controlled cleaning robot sent into a damaged reactor at Japan’s Fukushima nuclear plant had to be removed Thursday before it completed its work because of camera problems most likely caused by high radiation levels.

It was the first time a robot has entered the chamber inside the Unit 2 reactor since a March 2011 earthquake and tsunami critically damaged the Fukushima Da-ichi nuclear plant.

Tokyo Electric Power Co. said it was trying to inspect and clean a passage before another robot does a fuller examination to assess damage to the structure and its fuel. The second robot, known as the “scorpion,” will also measure radiation and temperatures.

Thursday’s problem underscores the challenges in decommissioning the wrecked nuclear plant. Inadequate cleaning, high radiation and structural damage could limit subsequent probes, and may require more radiation-resistant cameras and other equipment, TEPCO spokesman Takahiro Kimoto said.

“We will further study (Thursday’s) outcome before deciding on the deployment of the scorpion,” he said.

TEPCO needs to know the melted fuel’s exact location and condition and other structural damage in each of the three wrecked reactors to figure out the best and safest ways to remove the fuel. It is part of the decommissioning work, which is expected to take decades.

During Thursday’s cleaning mission, the robot went only part way into a space under the core that TEPCO wants to inspect closely. It crawled down the passage while peeling debris with a scraper and using water spray to blow some debris away. The dark brown deposits grew thicker and harder to remove as the robot went further.

After about two hours, the two cameras on the robot suddenly developed a lot of noise and their images quickly darkened — a sign of a problem caused by high radiation. Operators of the robot pulled it out of the chamber before completely losing control of it.

The outcome means the second robot will encounter more obstacles and have less time than expected for examination on its mission, currently planned for later this month, though Thursday’s results may cause a delay.

Both of the robots are designed to withstand up to 1,000 Sieverts of radiation. The cleaner’s two-hour endurance roughly matches an estimated radiation of 650 Sieverts per hour based on noise analysis of the images transmitted by the robot-mounted cameras. That’s less than one-tenth of the radiation levels inside a running reactor, but still would kill a person almost instantly.

Kimoto said the noise-based radiation analysis of the Unit 2’s condition showed a spike in radioactivity along a connecting bridge used to slide control rods in and out, a sign of a nearby source of high radioactivity, while levels were much lower in areas underneath the core, the opposite of what would normally be the case. He said the results are puzzling and require further analysis.

TEPCO officials said that despite the dangerously high figures, radiation is not leaking outside of the reactor.

Images recently captured from inside the chamber showed damage and structures coated with molten material, possibly mixed with melted nuclear fuel, and part of a disc platform hanging below the core that had been melted through. ”

by Mari Yamaguchi

source with photos

Lost in translation: Fukushima readings are not new spikes, just the same “hot mess” that’s always been there — Beyond Nuclear

” The ongoing Fukushima nuclear catastrophe has been back in the news lately following record high readings at the reactor site. Radiation levels were estimated to be 530 sieverts per hour, the highest recorded since the triple core meltdown in March 2011.

But upon further examination, the story has been misreported, in part due to mistranslation. In fact, according to Nancy Foust of SimplyInfo.org, interviewed on Nuclear Hotseat, there was no spike. High readings were in expected locations that TEPCO was only able to access recently. Therefore, the reading became evident because workers were getting closer to the melted fuel in more dangerous parts of the facility. In other words, it’s not a new hot mess, just the same hot mess it’s always been, pretty much from the beginning. The good news is nothing has changed. The bad news is – nothing has changed.

The confusion was initially caused by a translation error that SimplyInfo.org thinks occurred between the Kyoto News and Japan Times. Since this happened, Foust and her group have been trying to get news sources to correct the stories, with limited success.

The elevated radiation levels are inside containment (good news) in ruined unit 2 and were discovered using a camera, not proper radiation monitors. Therefore, the high reading may not be reliable since it is an estimate based on interference data with the camera. (It has been reported that the 530 Sievert/hour figure could be 30% too low, or 30% too high. 530 Sieverts/hour equates with 53,000 Rems/hour, a dose rate that would deliver a fatal dose of radiation to a person a short distance away, with no radiation shielding, in a minute or less exposure time.) TEPCO is planning on sending in a robot properly equipped with radiation detectors to take a reliable reading. Although no date has been given, TEPCO indicates it expects to deploy the robot within 30 days or so.

Foust theorizes that the bulk of the melted irradiated nuclear fuel is probably right below the reactor vessel burned into the concrete below. No one knows if melted irradiated nuclear fuel has gone into the ground water below that. ”

by Beyond Nuclear

source

Nuclear industry in crisis, Japan overview — Reneweconomy.com

” … Japan: Only two of the country’s 42 ‘operable’ reactors are actually operating. The future of Japan’s nuclear program remains a guessing game, but projections are being steadily reduced. According to the OECD’s Nuclear Energy Agency and the IAEA, installed capacity of 42.4 GW in 2014 could fall to as little as 7.6 GW by 2035 “as reactors are permanently shut down owing to a range of factors including location near active faults, technology, age and local political resistance.”

Another reactor was permanently shut down in 2016 (Ikata-1) in addition to five shut-downs in 2015 and the six Fukushima Daiichi reactors shut down in the aftermath of the March 2011 disaster. Japan also decided last year to permanently shut down the troubled Monju fast breeder reactor. For all the rhetoric about Generation IV fast reactors, and the A$130+ billion invested worldwide, only five such reactors are operating worldwide (three of them experimental) and only one is under construction.

(Australia’s nuclear lobby ‒ all three of them ‒ are promoting Generation IV fast reactors yet their arguments were rejected by the pro-nuclear Royal Commission. The Commission’s final report said that advanced fast reactors are unlikely to be feasible or viable in the foreseeable future; that the development of such a first-of-a-kind project would have high commercial and technical risk; that there is no licensed, commercially proven design and development to that point would require substantial capital investment; and that electricity generated from such reactors has not been demonstrated to be cost competitive with current light water reactor designs.)

Late last year, Japan’s Ministry of Economy, Trade and Industry revised the estimated cost of decommissioning the Fukushima Daiichi nuclear plant, and compensating victims of the disaster, to around A$244 billion. The latest estimate is four times greater than estimates provided in 2011/12. Indirect costs (e.g. fuel imports, adverse impacts on agriculture and fishing, etc.) are likely to exceed the direct clean-up and compensation costs. … ”

by Jim Green

read full article

Footage points to difficulty in removing possible melted fuel at Fukushima plant — The Mainichi

” The footage released on Jan. 30 by Tokyo Electric Power Co. (TEPCO) showing what could be melted fuel inside the No. 2 reactor at the disaster-stricken Fukushima No. 1 Nuclear Power Plant has highlighted the difficulty of salvaging the object, which is apparently stuck to footholds and other equipment at the facility.

TEPCO took the footage as part of its in-house probe into the No. 2 reactor and found that black and brown sediments — possible melted fuel — are stuck inside the reactor’s containment vessel over an extensive area.

“If what was captured in the footage was melted fuel, that would provide a major step forward toward trying our hand at unprecedented decommissioning work,” said Yoshiyuki Ishizaki, head of TEPCO’s Fukushima Revitalization Headquarters, during a press conference in the city of Fukushima on Jan. 30. “The finding may provide a major clue to future work to retrieve the object,” he added.

At the time of the March 2011 meltdowns at the plant, there were 548 nuclear fuel rods totaling some 164 metric tons inside the No. 2 reactor, but they apparently melted down after the loss of power sources for the core cooling system, with part of the melted fuel penetrating through the pressure vessel before cooling down at the bottom of the containment vessel. The temperature of the reactor core topped 2,000 degrees Celsius at the time of the accident, melting metals including nuclear fuel inside the reactor.

The melted fuel has since come in contact with underground water flowing from the mountain side, generating radioactively contaminated water every day. In order to dismantle the reactor, it is necessary to take out the melted fuel, but high radiation levels inside the reactor had hampered work to locate the melted debris.

On Jan. 30, apart from the footage, TEPCO also released 11 pictures taken inside the No. 2 reactor. The images show the sediments in question stuck to metal grate footholds and water is dripping from the ceiling. Further analysis of those images may provide information on the current status of the disaster and positional clues to decommissioning work.

The in-house probe, however, has only focused on the No. 2 reactor, and there is no prospect of similar probes into the No. 1 and No. 3 reactors starting anytime soon as they were severely damaged by hydrogen explosions following the 2011 meltdowns.

In April 2015, TEPCO introduced a remote-controlled robot into the No. 1 reactor by way of a through hole in its containment vessel, but the device failed to locate melted fuel inside due to high radiation levels. While the utility is planning to send a different type of robot into the No. 1 reactor this coming spring, it would be difficult to carry out a survey similar to that conducted at the No. 2 reactor, as radiation levels are high around the through hole in the No. 1 reactor’s containment vessel, from which a device could access to right below the No. 1 reactor.

The No. 3 reactor, meanwhile, holds roughly 6.5-meter-deep contaminated water inside its containment vessel, a far larger volume than that accumulated at the No. 1 and No. 2 reactors. TEPCO has thus been developing a robot that can wade through water. ”

by The Mainichi

source

Nuclear fuel debris that penetrated reactor pressure vessel possibly found at Fukushima No. 1 — The Japan Times

” Tepco on Monday found what may be melted nuclear fuel debris that penetrated the reactor 2 pressure vessel at the Fukushima No. 1 plant.

Tokyo Electric Power Company Holdings Inc. said more analysis and investigation is needed to confirm that the black lumps detected in the reactor’s containment vessel are indeed fuel debris.

The steel pressure vessel houses the nuclear fuel rods and is set up inside the surrounding containment vessel.

“At this point, it’s difficult to clearly identify what they are,” said Yuichi Okamura, general manager of Tepco’s nuclear power and plant siting division, during an evening news conference at the utility’s Tokyo headquarters.

Video footage from Monday’s probe showed black lumps that looked like something that had melted and then congealed, sticking to parts of a steel grating area at the base of the containment vessel.

The material could be melted paint, cable covers or pipe wrappings, Okamura said.

Still, this is the first time Tepco has detected anything in any of the facility’s three wrecked reactors that might be melted fuel rods since the outbreak of the crisis in March 2011. Okamura described the finding as “valuable information.”

The location of the debris and what form it is in are critical to eventually recovering the fuel.

Tepco plans next month to send in a remote-controlled robot equipped with a thermometer and dosimeter. Analyzing the temperature and radiation level will help identify whether the lumps are fuel debris, Okamura said.

The fuel melted after the March 11, 2011, earthquake and tsunami knocked out Fukushima No. 1’s power supply, including the vital cooling functions.

It is believed that reactor No. 2’s fuel rods melted and penetrated the bottom of the 20-cm-thick pressure vessel and fell in to the containment vessel.

Tepco has been conducting an investigation to check the interior of the containment vessel since last week.

In a previous try, workers inserted a rod equipped with a small camera as a precursor to sending in the remote-controlled robot.

The first attempt turned up nothing of note, but the utility then tried a longer rod — 10.5 meters long — on Monday that could capture images of the area beneath the pressure vessel.

The video footage also showed that water droplets were falling, which Tepco said must be cooling water being injected into the damaged pressure vessel.

Reactor 2 is one of three reactors, including 1 and 3, that experienced fuel meltdowns. ”

by Kazuaki Nagata

source

Fukushima disaster sways former advocate of nuclear power — Bloomberg

” The man blocking the world’s largest nuclear plant says he grew opposed to atomic energy the same way some people fall in love.

Previously an advocate for nuclear power in Japan, Ryuichi Yoneyama campaigned against the restart of the facility as part of his successful gubernatorial race last year in Niigata. He attributes his political U-turn to the “unresolved” 2011 Fukushima Dai-Ichi disaster and the lack of preparedness at the larger facility in his own prefecture, both owned by Tokyo Electric Power Co. Holdings Inc.

“Changing my opinion wasn’t an instant realization,” Yoneyama said in an interview. “It was gradual. As people say, you don’t know the exact moment you’ve fallen in love.”

Yoneyama won’t support the restart of the Kashiwazaki-Kariwa plant in Niigata until an investigation is complete into the chain of events that resulted in the triple meltdown at Fukushima, which he plans to visit Wednesday. While utilities don’t need approval of local authorities to restart plants, Japanese power companies are tradition-bound not to move ahead until they get their consent.

Local Opposition

Yoneyama, a 49-year-old doctor and native of Niigata, is one of the highest-profile local opponents pitted against a political establishment led by Prime Minister Shinzo Abe, which sees nuclear power as crucial for the country’s long-term energy security and environmental goals. Regulations and public opinion are keeping nearly all of Japan’s atomic stations shut almost six years after the accident at Fukushima, where the search has barely begun for fuel that burned through to the bottom of the reactors.

“If the local governor remains firmly opposed to the restart, it will be very difficult for the reactors to come back online,” said James Taverner, an analyst at IHS Markit Ltd. “In addition to the local government, building the support and trust of local residents is key.”

A Kyodo News poll on the day of Yoneyama’s October election showed about 64 percent of Niigata voters opposed the restart of Kashiwazaki-Kariwa, known popularly as KK. The restart of the facility was one of the key issues in the race to replace Governor Hirohiko Izumida, who was famous for his tough stance on Tokyo Electric. He unexpectedly announced in August that he wouldn’t seek a fourth term.

To the residents of the prefecture, Yoneyama was the candidate who would make nuclear safety a priority, while his main opponent gave off the vibe that he was a member of the nuclear restarts camp, the former governor said by e-mail.

Switching Sides

In last year’s gubernatorial race for the southern prefecture of Kagoshima, where Kyushu Electric Power Co. operates the Sendai nuclear plant, a three-term incumbent was defeated by an opponent campaigning to temporarily close the reactors. A district court last year barred Kansai Electric Power Co. from running two reactors at its Takahama station in western Japan only weeks after they’d been turned back on.

Yoneyama supported bringing back online Japan’s reactors during his unsuccessful bid in 2012 for a seat in Japan’s lower house. The country was being forced to spend more on fossil fuel imports after the disaster, so restarting the plants was needed to help the economy recover, he said at the time.

Though Yoneyama’s position switch helped secure his first electoral victory after four failed campaigns for the country’s legislature, nuclear opponents see him driven by more than political opportunism.

“I had my reservations about Yoneyama,” said Takehiko Igarashi, an official at the Niigata division of the anti-nuclear group Nakusou Genpatsu. “But after he was vetted and endorsed by the Japanese Communist Party and other smaller parties that have an anti-nuclear slant, I knew that I could trust him.”

evTokyo Electric and Abe’s government see restarting KK as one way for Japan’s biggest utility to boost profits and help manage its nearly 16 trillion yen ($139 billion) share of the Fukushima cleanup. Resuming reactors No. 6 and No. 7 will boost annual profits by as much as 240 billion, the utility has said.

The economic argument, however, is beginning to hold less sway, with Yoneyama saying the benefits to the local economy are ‘overstated.’ While the prefecture risks missing out on 1.1 billion yen a year in government support without the restart, that represents a small slice of the prefecture’s budget, which tops 1 trillion yen, according to Yoneyama.

Abe, a strong backer of atomic power, leads a government aiming for nuclear to account for as much as 22 percent of Japan’s energy mix by 2030, compared with a little more than 1 percent now.

While restart opponents like Yoneyama demand the government guarantee the safety of the reactors, they’ve also criticized evacuation and emergency response plans as inadequate.

In his first meeting with Tokyo Electric executives since taking office, Yoneyama earlier this month told Chairman Fumio Sudo and President Naomi Hirose that he won’t support KK’s restart until a new evacuation plan is drawn up using the results of a Fukushima investigation. Tepco will fully cooperate with the probe and stay in communication with the governor, the company said in response to a request for comment.
“Once I realized that the Fukushima disaster couldn’t be easily resolved, of course my opinion changed,” Yoneyama said. “If another accident occurs, overseas tourism will become a distant dream. Even Japanese may flee the country.” ”

by Stephen Stapczynski and Emi Urabe

source