Thursday, March 16, 2017

Robots designed to monitor Fukishima reactor fail

The robots sent so far to investigate the reactive zone at the Fukushima nuclear facility are simply not up to the task. The head of Tokyo Electric Power Company's (TEPCO) decommissioning admitted that the company needed to be more creative.

The Fukushima nuclear power plant suffered massive damage back in 2011 after three of six nuclear reactors suffered meltdowns after a hit by a devastating 9.0 magnitude earthquake and then associated tsunami waves. As a result of the radiation, more than 100,000 people who lived nearby in Fukushima Prefecture had to move out. This was the largest nuclear disaster since Chernobyl in the Ukraine in April of 1986.
As part of the cleanup process, robots are sent in to parts of the site where radiation levels are too high for workers. In the middle of February, a "Scorpion" robot got bogged down and was unable to move but it was not clear whether the cause was obstacles in its way or the effects of radiation as discussed in a recent Digital Journal article. Radiation levels inside the # 2 reactor were estimated last week at 650 sieverts per hour at one spot. This would effectively shut down robots in hours. However, the robots are kept moving from such areas to avoid this happening. A more recent article claims the robot was blocked by deposits thought to be a mixture of melted fuel and broken pieces of the reactor. There were two other earlier failures. One robot got stuck in a gap and another ran out of fuel.
Naohiro Masuda, the TEPCO Head of Decommissioning said: "We should think out of the box so we can examine the bottom of the core and how melted fuel debris spread out." Masuda said he wants to send in another robot before he decides on methods to be used to remove debris. Officials want site clean up to begin by 2021. The cleanup is expected to cost tens of billions of dollars and to last around four decades. As noted in a Digital Journal article, last month a radiation level of 530 sieverts was measured in Reactor # 2. Exposure to just four sieverts can be lethal. TEPCO also discovered a tank with very high levels of radiation:The plant's operator, Tokyo Electric Power (Tepco), said radiation near the bottom of the tank measured 1,800 millisieverts an hour – high enough to kill an exposed person in four hours. Tepco said water levels inside the tank had not changed, indicating there had not been a leak. But the company said it had yet to discover the cause of the radiation spike.
Jeju Air a low-cost South Korean carrier announced that it would not use Fukushima Airport close by because of fears of radiation. Apparently some of its customers said on line that they did not want to fly over Fukushima. However, another article claims that it was members of the airline staff who expressed concerns about flying over the reactors as well.

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