27 Février 2019
February 18, 2019
EDITORIAL: Probe shows challenges posed by melted fuel at Fukushima plant
A specially designed, remotely controlled probe touched melted nuclear fuel debris at the bottom of a ruined reactor at the Fukushima No. 1 nuclear power plant in the first successful operation to inspect radioactive debris through direct contact.
The plant’s operator, Tokyo Electric Power Co. (TEPCO), lowered the rod-like probe outfitted with a tong-like pinching device into the primary containment vessel of the No. 2 reactor at the crippled plant and used the machine to successfully lift pieces of the debris several centimeters.
The removal of the fuel debris is the biggest challenge in the long process of decommissioning the reactors, which will take at least three to four decades. The lifting of debris is a ray of hope in the grim battle to overcome the formidable challenge.
But the success was tempered by the fact that there were large chunks with slick surfaces the robot’s pinchers were unable to grab. The probe found that deposits in various conditions lie scattered about the bottom of the vessel. Some pieces are apparently entangled in the surrounding equipment.
The images captured by the probe came as a fresh reminder of the daunting enormity of the challenge of removing all the debris.
TEPCO needs to seek steady, if slow, progress in the cleanup effort by taking one step at a time.
Tasks in and around the No. 1 to No. 3 reactors at the nuclear plant cannot be carried out by humans because of dangerously high radiation levels. Nuclear fuel in the core of these reactors overheated and melted down after towering tsunami triggered by an epic earthquake knocked out vital cooling systems on March 11, 2011.
TEPCO has made a series of attempts to use remotely controlled robots and cameras to examine the situation inside these reactors, but only small parts of the reactors’ innards have been revealed so far.
Under the plan developed by the government and the utility, a small amount of debris should be removed from the No. 2 reactor in the second half of fiscal 2019, which starts in April.
Data to be collected from the operation will also offer important clues to what actually occurred inside the reactors during the catastrophic accident. TEPCO needs to study them carefully and meticulously to uncover and assemble facts.
Full-scale operations to remove debris containing melted uranium fuel from the reactors are scheduled to start in 2021.
TEPCO is responsible for identifying the make-up of the debris by using collected data and develop equipment and techniques necessary to accomplish the mission by working with related companies.
TEPCO should avoid the risk of trouble by launching full-scale debris removal operations without sufficient preparations.
The firm needs to map out reliable plans and procedures for safe and steady operations.
In doing so, the firm should not remain wedded to the traditional nuclear industry framework. It would have a better chance of achieving necessary technological innovations and breakthroughs if it pays serious attention to opinions and proposals from a wide range of companies and research institutes including those in other areas.
The experiences and expertise it accumulates through its operations at the Fukushima plant could be useful for the decommissioning of other reactors in Japan.
One big question that needs to be sorted out as TEPCO begins to remove debris is how to dispose of the molten nuclear fuel.
The Fukushima prefectural government demands that the nuclear waste from the stricken plant including debris should be eventually moved out of the prefecture.
But there has been little serious debate on specifics. Both the government and TEPCO should confront this issue head-on.
It is vital for them to offer sufficient and straightforward explanations about their efforts to tackle this problem to local governments and residents concerned while seeking to win their understanding through sincere discussions.
It is simply impossible to complete the long and tricky process of decommissioning the reactors without support from the local communities. The government and the utility should keep this firmly in mind.