11 Avril 2015
April 11, 2015
By TSUYOSHI NAGANO/ Staff Writer
A sleek shape-changing robot sent to probe a highly radioactive containment vessel of the crippled Fukushima No. 1 nuclear power plant got stuck hours after it was deployed, dealing a major blow to decommissioning work.
Tokyo Electric Power Co., the plant operator, said April 10 that the tubular-shaped robot stalled inside the first floor of the No. 1 reactor's containment vessel. TEPCO has yet to determine why the device became immovable or when it will be able to recover the robot.
“There is the possibility that the (robot's) cable got entangled, but we have yet to know what caused this,” a TEPCO official said.
The robot was developed by the International Research Institute for Nuclear Decommissioning (IRID) to chart areas inside the containment vessel where humans cannot enter because of high radiation levels.
Measuring 60 centimeters long in its normal state, the robot is able to change its shape depending on the space it is trying to enter and is controlled remotely via a connecting cable.
The robot entered the containment vessel through piping on April 10 at 9:30 a.m. It began its journey around the netted first floor of the vessel at 11:20 a.m. to measure the temperature and radiation levels while transmitting images of the surrounding conditions. But after covering about two-thirds of its planned route, the robot came to a standstill after 2 p.m.
According to an IRID official, the operators tugged on the robot's cable and sent instructions for it to change shape, but it still would not move. The robot’s camera, dosimeter and temperature gauge were not damaged, and the robot was still capable of transmitting data.
The robot is essential to carrying out preliminary studies ahead of a full-blown investigation scheduled for the end of this fiscal year. It is part of preparations to retrieve melted nuclear fuel, the toughest part of the decommissioning process.
FUKUSHIMA – A remote-controlled robot inserted to survey the inside of the No. 1 reactor at the damaged Fukushima No. 1 nuclear power plant has stopped functioning, Tokyo Electric Power Co. said.
As a first step in the utility’s effort to remove melted nuclear fuel from the bottom of the unit’s primary containment vessel, the shape-shifting robot was sent in Friday morning to find the exact location of the highly radioactive debris.
Set to cover some 20 meters of the first floor on the first day, the robot began its trip at around 11:20 a.m. but halted at around 2:10 p.m. after completing two-thirds of the route, Tepco said.
The utility said footage from the robot’s camera shows it passed an opening leading to the vessel’s basement, where the molten fuel is believed to have ended up after the core meltdowns occurred after the March 2011 quake and tsunami.
April 10, 2015
Apr. 10, 2015 - Updated 18:51 UTC+2
The operator of the damaged Fukushima Daiichi nuclear power plant says a robotic probe has stopped functioning inside the No.1 reactor containment vessel.
Tokyo Electric Power Company is trying to determine the condition inside the containment vessel as it emits extremely high radiation before removing the melted fuel.
TEPCO sent the 60-centimeter, snake-like robot into the vessel through a pipe. The remote-controlled robot is designed to record images of damage and measure internal radiation levels.
Engineers say they were unable to move the robot after it negotiated obstacles over a 10 meter course.
They say the remote-control cable may have been caught on something, or a belt that propels the robot may have malfunctioned.
However, engineers say the robot is responding to instructions. They say the robot is sending them data, such as images and radiation-levels.
They say the robot has finished surveying 14 of 18 areas scheduled on Friday. But they fear the robot could break down because of the high radiation levels of up to 11 Sieverts per hour inside the vessel.