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Tepco’s Toughest Robot Fails Inside Fukushima Reactor

© AFP 2022 / TORU HANAI Men wearing protective suits and masks work in front of welding storage tanks for radioactive water, under construction in the J1 area at the Tokyo Electric Power Co's (TEPCO) tsunami-crippled Fukushima Daiichi nuclear power plant in Okuma in Fukushima prefecture. (File)
Men wearing protective suits and masks work in front of welding storage tanks for radioactive water, under construction in the J1 area at the Tokyo Electric Power Co's (TEPCO) tsunami-crippled Fukushima Daiichi nuclear power plant in Okuma in Fukushima prefecture. (File) - Sputnik International
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The ‘tough-built’ radiation-resistant robot, made to withstand up to 1000 sieverts per hour (Sv/hr) of radiation, had to be called back prematurely due to radiation-induced glitches, indicating that radiation levels in Fukushima reactor are even higher than previously estimated.

Members of the media wearing protective suits and masks report as they are escorted by TEPCO employees at Tokyo Electric Power Co. (TEPCO)'s tsunami-crippled Fukushima Daiichi nuclear power plant in Okuma, Fukushima prefecture on February 20, 2012. - Sputnik International
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‘Unimaginable’ – Understanding Radiation Levels Inside Fukushima Reactor
Tokyo Electric Power Company (Tepco), the owner and operator of the now-defunct Fukushima-1 nuclear plant in Japan, had to pull its toughest radiation-resistant robot out of its Unit 2 reactor prematurely. The robot, built to withstand up to 1000 Sv/hr, failed to last the projected two hours inside the reactor, before starting to glitch.

As Sputnik reported earlier, Fukushima-1 Unit 2 reactor radiation readings had been estimated at "unimaginable" levels of 530 Sv/hr. This level of radiation is beyond extreme, even in comparison to the inside of the Chernobyl reactor, where radiation levels are ‘only' 34 Sv/hr. The Chernobyl radiation levels are high enough to cause death in humans in about 20 minutes, and Fukushima's earlier estimation, of 530 Sv/hr, is likely to kill a man in moments. Alarmingly, it is also more than powerful enough to kill purpose-built radiation-protected robots.

Tepco has previously lost five, less-shielded robots inside the Fukushima reactor. While earlier estimations showed 74 Sv/hr readings, Tepco,  charged with decommissioning the destroyed facility, has been unpleasantly surprised to find that radiation levels underneath the reactor have spiked, due, in part, to nuclear fuel believed to have melted out of the reactor core. As a result, the company ordered the toughest robot available to clear the way for cleanup machines. Intended to function for two hours, Tepco pulled the machine prematurely, as its cameras developed noise and the image became too dark to use.

A part of the roof of a building covering the Unit 1 reactor, left, is seen removed at the Fukushima Dai-ichi nuclear power plant in Okuma, Fukushima prefecture, northeastern Japan, Wednesday, Nov. 12, 2014 - Sputnik International
Russia, Japan to Act Further on Overcoming Fukushima Accident Results - Rosatom
Radiation levels inside the damaged reactor are much higher than previously estimated, according to reports. Judging by camera noise and overall operation time, the team has increased its estimation to 650 Sv/hr. The robot failed to complete its mission of removing debris, including, it is thought, the remains of previous robots, inside the reactor chamber, and now the next robot to be sent inside will have less time to perform its job. The process of decommissioning the nuclear plant is expected to take at least 40 years, and cannot begin before a full assessment of the damage.

Tepco has reported that they have only acquired images of the reactor chamber, showing damaged structures, coated with molten material, possibly mixed with molten nuclear fuel. The robot was able to acquire images of a part of a disc platform that was located below the reactor core that had been melted through. This discovery supported earlier speculation that nuclear fuel has found its way outside of the reactor. Tepco continues to assert that no radiation is leaking outside of the building.

 

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