27 Février 2017
February 27, 2017
Tokyo Electric Power Co. (TEPCO) has failed to grasp the entire picture of melted fuel possibly accumulating inside the container vessel of the No. 2 reactor at the Fukushima No. 1 Nuclear Power Plant. The radiation levels inside the vessel are extremely high, to the extent a human could be killed in less than a minute, and even a robot designed to conduct a probe inside went down quickly.
The Mainichi Shimbun visited the disaster-stricken plant late last year ahead of the sixth anniversary of the nuclear meltdowns at the facility in March.
On the early morning of Dec. 24, 2016, a group of 26 workers assembled at a building housing the No. 2 reactor when it was still dark outside. The workers were from heavy machinery giant IHI Corp. and other companies engaged in disaster recovery work. On top of their protective Tyvek suits, they were wearing special protective ponchos. They also had four-layer gloves on, with plastic tape wrapped around their wrists. The outfit made them sweat though it was the middle of winter.
In order for TEPCO to move ahead with decommissioning work on the No. 1 through No. 3 reactors at the plant, the utility needs to find out how much melted nuclear fuel lies inside the facilities, and where, in the aftermath of the meltdown of 1,496 fuel rods. The 26 workers were tasked with drilling a hole measuring 11.5 centimeters in diameter in the No. 2 reactor's container vessel to open the way for the probe robot, using a remotely controlled machine.
Ryosuke Ishida, 28, an employee of a related company in Hokkaido, was in charge of removing the machinery that was used in the drilling work. In order to ward off the severely high radiation, he was wearing a lead jacket weighing 10 kilograms on top of his already tightly sealed protective gear. Each worker was allowed only five minutes for their task to keep their radiation exposure doses to no more than 3 millisieverts a day. The dosimeters they were carrying with them were set to beep when the radiation level reached 1.5 to 2 millisieverts, with an additional alarm set to go off when radiation doses hit every one-fifth of those levels.
Ishida's dosimeter beeped just under a minute after he stepped inside the No. 2 reactor building. "Is it beeping already?" he thought to himself. The radiation levels vary greatly depending on where one stands inside the facility. Although Ishida had got a firm grasp on where the hot spots were during pre-training, he found himself "inadvertently standing on highly radioactive spots as I was focused on work."
While trying to calm himself down, Ishida sped up his manual work. Alas, a machine component for turning a bolt fell off and rolled on the floor. "Damn, I'm running out of time," he thought. His full face mask went all white as he sweated physically and emotionally, blocking his view. By the time he finished picking up the fallen component and wrapped up his work, he was sweating all over his body.
"It's a battle against radiation at the site," Ishida recalled. He added, though, "Because nobody else wants to do the job, I find it all the more worthwhile and take pride in it." (By Mirai Nagira, Science & Environment News Department)