New robot for decommissioning

February 6, 2017

New robot built to study inside of No. 1 reactor at Fukushima plant

http://www.asahi.com/ajw/articles/AJ201702060040.html

By KOHEI TOMIDA/ Staff Writer

HITACHI, Ibaraki Prefecture--Another robot has been developed for the elusive goal of locating melted fuel and surveying the interior of the No. 1 reactor at the Fukushima No. 1 nuclear plant.

A team of engineers and researchers from Hitachi-GE Nuclear Energy Ltd. and the International Research Institute for Nuclear Decommissioning revealed the robot on Feb. 3.

Tokyo Electric Power Co., operator of the plant, plans to deploy the robot into the No. 1 reactor before the end of March.

The robot will be fitted with a censoring unit mounted with a camera, dosimeter and lighting. Its purpose is to give TEPCO an idea of the location and condition of the melted nuclear fuel in the reactor.

Most of the melted fuel is believed to have fallen through the reactor’s pressure vessel, landed on the bottom of the surrounding containment vessel, and is soaking in cooling water about 2 meters deep.

The new robot will maneuver around metal grating originally set up for maintenance work about 3.5 meters above the bottom of the containment vessel.

At each of five survey points, the robot will lower the censoring unit through the grating. The unit can operate in water.

In April 2015, TEPCO sent two robots into the No. 1 reactor, but they could not locate the melted fuel.

One of them became stuck, and high radiation levels disabled the camera on the other. TEPCO abandoned the machines in the reactor.

On Jan. 30, a remote controlled video camera sent into the No. 2 reactor took what are believed to be the first images of melted fuel at the plant.

February 3, 2017

New robot to inspect Fukushima reactor unveiled

https://www3.nhk.or.jp/nhkworld/en/news/20170203_21/

A test run of a robot designed to inspect a reactor at a damaged nuclear power plant in Fukushima Prefecture was shown to the public at a plant in Ibaraki Prefecture, north of Tokyo on Friday.

The operator of the Fukushima Daiichi nuclear plant plans to send the robot into one of the facility's damaged reactors to find out the condition of melted fuel there.

The robot is 70 centimeters long and less than 10 centimeters wide. It's designed to drop a camera and dosimeter using a fishing line-like cable to look deep inside a containment vessel.

Tokyo Electric Power Company, or TEPCO, plans to use the robot next month to inspect the plant's No.1 reactor as part of efforts to decommission the plant.

Fuel at the reactor is believed to have melted through the core during the 2011 accident and accumulated at the bottom of the containment vessel.

The robot is to be remotely controlled while inside the vessel, which humans cannot enter.

The camera may not be able to show conditions in 2-meter-deep contaminated water. Engineers plan to estimate the location of the fuel based on radiation measurements.

An engineer at Hitachi-GE Nuclear Energy who's involved in the robot's development says locating melted fuel would provide a significant clue about how to remove it.

TEPCO sent a remote-controlled camera into the plant's No.2 reactor last month.