The robot developed by Jacobs for collecting debris at Fukushima Daiichi (Image: Jacobs)
Jacobs ENGINEERING Group has designed and built a remote-controlled robot to collect debris from Japan’s Fukushima nuclear power plant to assess the condition of a damaged reactor at the facility.
Now rendered inoperable following its catastrophic collapse in March 2011 due to an earthquake and tsunami, Jacobs is helping the Tokyo Electric Power Company (Tepco) assess the plant’s readiness for decommissioning in the under a five-year framework agreement.
As part of the deal, Jacobs engineers in the UK created a robotic tool to collect the pebble-like debris that settled at the bottom of the reactor’s containment vessel after the accident.
The debris comes from the fuel and the metal sheath that formed the outer casing of the fuel rods of units 1 to 3 of Fukushima Daiichi, the most affected by the incident. These then resolidified as fuel debris.
To reduce the risk to personnel from this fuel debris, the robot will collect it from the reactors. Debris up to 10mm in size can be collected by the robot from the damaged containment vessel with a bucket type retrieval device.
In preparation for the test, the robot recently passed 300 extremely demanding functional, operational, performance and geometric tests to meet the requirements of Mitsubishi Heavy Industries (MHI), which works with the International Research Institute for Nuclear Decommissioning to implement the project.
Trials have shown that it takes no more than eight minutes to collect the samples and it is expected that after selection in Japan a radiation-resistant version of the robot will be built to perform the task.
The recovered fuel debris will then be stored in the new storage facility to be built on site.
Karen Wiemelt, Jacobs Energy Senior Vice President, Security & Technology, said, “This is a great example of how we combine innovative engineering and deep nuclear knowledge to help decommissioning agencies meet the challenge of transforming old sites into a safe end state”.
Last year, Tepco announced that the Japanese government would allow the company to discharge treated wastewater stored at the Fukushima Daiichi nuclear site into the sea from 2023.
Despite concerns from environmentalists and human rights advocates, the industry welcomed the announcement.