NARAHA, FUKUSHIMA PREF. – A research institute has used a full-size mock-up of part of a nuclear reactor to conduct trial decommissioning experiments for use on the disaster-hit Fukushima No. 1 plant.
The International Research Institute for Nuclear Decommissioning (IRID) carried out the experiments Tuesday using a 20-meter wide, 12-meter high model of the No. 2 reactor’s suppression chamber and torus room — areas located below the reactor’s containment vessel.
The IRID was established in 2013 by nuclear plant makers, power firms and government organizations to develop technology needed for the decommissioning of the Fukushima plant, which was wrecked by the March 11, 2011, earthquake and tsunami. After the disaster, three of the plant’s reactors suffered meltdowns in the world’s most severe nuclear crisis since the 1986
The model is located at the Naraha Remote Technology Development Center, near the crippled Fukushima No. 1 plant.
“We would like to continue testing until next summer, approximately, and use (the outcomes) in deciding methods to retrieve fuel debris,” said IRID Executive Director Atsufumi Yoshizawa.
Removing nuclear fuel debris is perceived as one of the most difficult challenges in the decommissioning process.
With radiation emitting from the debris, a method is under consideration to fill containment vessels at the plant with water and remove debris from the top of the vessels, using the water to provide some protection from the harmful radiation.
Challenges in implementing this method include how to prevent contaminated water from leaking through cracks in the vessels.
During Tuesday’s experiments, which were open to the media, workers wearing protective suits and masks attempted to insert a hose into the torus room mock-up while using remote cameras to observe their work.
A further experiment to stop water leaking from a suppression chamber is planned.