21 July, 2017
A robot entered a damaged reactor at Japan's Fukushima nuclear plant this week to take pictures of the reactor destroyed by an earthquake and tsunami in 2011.
The robot, nicknamed 'The Little Sunfish,' is very small – about the size of a loaf of bread. It has lights, five propellers, and two cameras, among other data collection tools.
Toshiba Corp., the electronics and energy company, and the International Institute for Nuclear Decommissioning, a government-funded group, developed the Little Sunfish.
Four operators control the Little Sunfish from afar. It is designed to tolerate radiation of up to 200 sieverts, a level that can kill humans instantly.
Robots are important for decommissioning the plant
Tokyo Electric Power Company, or TEPCO, is the plant's operator. TEPCO spokesman Takahiro Kimoto praised the robot's work, saying it took pictures of the underwater damage that had not been previously seen. However, the pictures showed no sign of the melted nuclear fuel that researchers hope to find, he said.
Robots are a key part of the plan to decommission the damaged plant. However, high levels of radiation and damage have stopped robots from doing their work in the past.
In previous tests, two robots became stuck inside two of the plant's other reactors.
A scorpion-shaped robot failed inside the plant's Unit 2 reactor. A snake-shaped robot designed to clear debris for the scorpion probe was removed after two hours when its cameras failed. The cameras failed because radiation levels were five times higher than anticipated.
Kimoto said the Little Sunfish showed that the Unit 3 reactor chamber was "clearly more severely damaged" than Unit 2, which was explored by the scorpion probe.
Scientists need to know the melted fuel's exact location and understand the damage in each of the three wrecked reactors. This information will help them to decide on the safest and most efficient ways to remove the fuel.
Japanese officials say they want to decide on methods for removing the melted nuclear fuel this summer. They hope to start the removal work in 2021.
I'm John Russell.
The Associated Press reported this story. John Russell adapted it for Learning English. Hai Do was the editor.
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Words in This Story
reactor – n. a large device that produces nuclear energy
propeller – n. a device with two or more blades that turn quickly and cause a ship or aircraft to move
decommission – v. to officially stop using (a ship, weapon, dam, etc.) : to remove (something) from service
sievert – n. physics the standard unit in the International System of Units (SI) of dose equivalent having the same biological effect as one joule of x-rays per kilogram of recipient mass (or one gray)
efficient – adj. capable of producing desired results without wasting materials, time, or energy