NHK has learned that workers failed to check the alignment of pipes to be used for the test retrieval of nuclear fuel debris from a reactor at the damaged Fukushima Daiichi nuclear plant. The problem led to a postponement of the test.
Tokyo Electric Power Company, the operator of the plant, suspended the test removal of nuclear fuel debris from the plant’s No. 2 reactor shortly before the work was supposed to begin on August 22.
It was the first such attempt after the powerful earthquake and tsunami triggered meltdowns at the plant in 2011.
The debris-removing equipment consists of a thin, extendable pipe that is designed to be pushed into the reactor containment vessel using five other pipes.
But the order of these five pipes was found to be incorrect just before the experimental work was scheduled to begin.
The pipes were placed at the plant by subcontractor workers on July 28.
Sources said the workers had failed to rehearse the task before placing the pipes on-site. They added that neither TEPCO nor its original contractor checked the pipe alignment during the nearly month-long period leading up to the day of the removal process.
The sources say that high levels of radiation at the site, which limit the time available for work, and the fact that workers were wearing special masks may have led to the insufficient checks.
TEPCO reportedly believes the mishandling was caused by insufficient work procedures that did not take these conditions into account as well as inadequate checks.
It is expected to report findings from its investigation to the industry ministry as early as Monday.