Tag Archives: Fukushima Japan

Robots to the Rescue: Fukushima Japan

jorange on equipment probably melted nuclear fuel

A robot operating deep inside a failed reactor at the stricken Fukushima nuclear plant north of Tokyo has revealed what appears to be stalactites of melted nuclear fuel, the plant’s operator has said.
The discovery is considered a key development in the decommissioning process of the plant, which suffered a catastrophic meltdown in 2011 after a huge tsunami swamped the facility.
Operating remotely within submerged parts of the Fukushima Daiichi plant’s Unit 3 reactor, the robot sent back 16 hours worth of images of massive, lava-like fuel deposits on the floor of the pedestal, a part of the reactor that sits underneath and supports the core….

The discovery is key to determining how to further advance the cleanup of the plant, a process that is expected to take decades.  “This was the first time that we could confirm the status inside the pedestal,” TEPCO spokesperson Maki Murayama said. “This is a big step towards the decommission process.”..

Having entered the stricken Pressure Containment Vessel (PCV) through a pipe designed to prevent the escape of radioactive gas, the robot descended into the cooling water which accumulated following the accident.
The device was equipped with thrusters to navigate through the water, and featured front and rear cameras.  The small “radiation-hardened, screw-driven” submersible robot was designed to fit through the narrow, 14-centimeter (5.5-inch) diameter entrance of the pipe, according to the Tokyo-based International Research Institute for Nuclear Decommissioning (IRID), which developed the device alongside technology company Toshiba.

As the robot navigates through the ruined reactor, melted equipment and the fuel deposits can be seen.

The mission was launched after previous photographic inspection of the Unit 3 reactor suggested that, “during the accident, fuel assemblies melted from the excess heat, dropping from their original position down to the pedestal area,” according to a statement released by TEPCO.

Excerpt from Euan McKirdy and Yoko Wakatsuki, Fukushima robot reveals first sign of melted fuel in submerged reactor, CNN, July 24, 2017

Fukushima Nuclear Waste will Go Here

Okuma, Futaba and Nahara disposal locations Fukushima

Fukushima prefectural authorities have asked the Environment Ministry to reduce from three to two the number of sites it plans for the temporary storage of radioactive debris generated by the Fukushima No. 1 nuclear power plant disaster.  Fukushima Governor Yuhei Sato on Feb. 12 submitted a request to Environment Minister Nobuteru Ishihara and Takumi Nemoto, the minister in charge of post-quake reconstruction, asking them not to build a storage facility in the town of Naraha so that its residents can return home earlier.  Based on the request, Ishihara said the Environment Ministry will review the initial plan to erect facilities in Naraha, as well as the towns of Okuma and Futaba.

The central government intended to construct intermediate storage facilities in the three towns, all in Fukushima Prefecture, that are capable of storing 13.1 million, 12.4 million and 2.5 million cubic meters of debris, respectively. The smallest of the sites was to be built in Naraha.

However, Sato argued in his request that if collected debris were burned to reduce its volume, the two larger sites could accommodate all the waste.  The governor also proposed that the ministry build a plant to process the ash from debris with radioactive values at 100,000 becquerels per kilogram or lower in Naraha instead…Elsewhere though, many other municipalities in the prefecture have urged the prefectural government to quickly facilitate the building of those facilities because radioactive soil and other associated waste generated by the Fukushima nuclear disaster are filling up temporary storage sites throughout the prefecture. The Environment Ministry estimates that 1.6 million cubic meters of debris was stored across Fukushima Prefecture as of the end of last October.

Excerpt, Fukushima seeks limit on radioactive waste disposal sites, THE ASAHI SHIMBUN, Feb. 13, 2014

Nuclear Protesters and the Establishment: Japan

anti-nuclear protest japan, 2011.  Image from wikipedia.

Eight million people signed an Internet petition demanding an end to nuclear power and hundreds of thousands joined public protests. Yet Japan handed an election landslide to the most pro-atomic option on offer.  Anti-nuclear activists have been left licking their wounds after the first national poll since the tsunami-sparked disaster at Fukushima saw an apparent melting away of public anger as the country welcomed back the establishment…

The Liberal Democratic Party bagged 294 of the 480 seats in the lower house, crushing their opponents, the biggest of which won only 57 seats.  Where smaller parties offered an end to nuclear power — immediately, over ten years, or within three decades — the LDP pledged only to “decide” on reactor restarts within three years.

Commentators say the pro-business party is likely to give the green light to power companies. Markets agree, with shares in Fukushima operator Tokyo Electric Power (TECPO) surging around 50 percent in two days after the win.  The problem, said the left-leaning Asahi Shimbun newspaper, was that other issues trumped nuclear; voters were frustrated with Japan’s economic malaise, huge public debts, fragile employment and diplomatic friction with China.  The public were looking for a way to punish the ruling Democratic Party of Japan for its policy failures…In fact, says the Asahi, the anti-nuclear vote was almost completely neutralised because of the fragmentation caused by this mushrooming of parties.

Excerpts from Hiroshi Hiyama, Japan anti-nuclear vote melts away, Agence France Presse, Dec. 23, 2012

See also Radioactive Water

Nuclear Waste

Fukushima Decontamination: lengthy and costly

Japan faces the daunting task of decontaminating large areas of land around the Fukushima Daiichi nuclear complex, which is still leaking low levels of radiation nearly six months after an earthquake and tsunami triggered a nuclear meltdown.  In a meeting with local officials on Saturday, the government estimated it could take more than 20 years before residents could safely return to areas with current radiation readings of 200 millisieverts per year, and a decade for areas at 100 millisieverts per year.  The estimates, which merely confirm what many experts have been saying for months, are based on the natural decline of radiation over time and do not account for the impact of decontamination steps such as removing affected soil….The Japanese government unveiled guidelines this week with the aim of halving radiation in problem areas in two years, but for spots with very high readings it could take much longer to reach safe levels….Japan has banned people from entering within 20 km (12 miles) of the Fukushima plant, located 240 km northeast of Tokyo. Around 80,000 people have been evacuated since the March 11 quake and tsunami and many are living in shelters or temporary homes.

The government’s announcement follows the release of data this week showing radiation readings in 35 spots in the evacuation zone above the 20 millisieverts per year level deemed safe by the government. The highest reading was 508 millisieverts in the town of Okuma, about 3 km from the nuclear plant.  Kan, who resigned on Friday [Aug. 26, 2011] as leader of the ruling Democratic Party of Japan amid intense criticism of his handling of the nuclear crisis, also told Sato that the government planned to build a temporary storage facility in Fukushima for radioactive waste.

The accident at the Fukushima plant is likely to have released about 15 percent of the radiation released at Chernobyl in 1986, Japan’s Nuclear and Industrial Safety Agency has estimated.But that is still more than seven times the amount of radiation produced by Three Mile Island accident in the United States in 1979, and experts have estimated Japan’s decontamination efforts could cost as much as 10 trillion yen ($130 billion).

Osamu Tsukimori and Nathan Layne, Reuters, Aug. 27, 2011