Images indicate bigger challenge for TEPCO at Fukushima plant

A video taken on Jan. 30 shows the bottom of the No. 2 reactor’s pressure vessel at the Fukushima No. 1 nuclear power plant. Water used to cool the nuclear fuel is dripping, and possible melted fuel is seen strewn on grating for maintenance work. (Provided by Tokyo Electric Power Co.)

 

If confirmed, the first images of melted nuclear fuel at the Fukushima No. 1 nuclear plant show that Tokyo Electric Power Co. will have a much more difficult time decommissioning the battered facility.

The condition of what is believed to be melted fuel inside the No. 2 reactor at the plant appears far worse than previously thought.

Before the pictures were taken by a remote-controlled video camera on Jan. 30, TEPCO presumed that most of the nuclear fuel at the No. 2 reactor had remained within the reactor’s pressure vessel. That presumption was based on findings of a study conducted last year involving cosmic rays.

As a result, TEPCO did not expect the camera to detect possible nuclear fuel debris below the pressure vessel.

 

But the images showed black lumps scattered on a wire-mesh grating in the lower part of the containment vessel, which encloses the pressure vessel. This indicates that the fuel melted through bottom of the pressure vessel, spilled through the grating and fell on the floor of the containment vessel.

 

This image of the area below the No. 2 reactor’s pressure vessel at the Fukushima No. 1 nuclear power plant was taken on Jan. 30. Experts believe nuclear fuel melted the paint and components of equipment nearby and has hardened. (Provided by Tokyo Electric Power Co.)

 

The grating, which was used by maintenance workers before the disaster, was partially bent.

The images could show only part of the melted fuel in the No. 2 reactor. And there is still no indication on how widespread the black lumps were strewn, their volume and state.

TEPCO and government authorities in fiscal 2018 plan to decide on a method to retrieve the melted fuel from each of the three crippled reactors and start the removal work in 2021.

But a number questions remain unanswered, such as how to reduce workers’ radiation exposure, where the removed fuel will be kept, and when it will be disposed of.

The pictures raise another question: How will workers cut out the wire-mesh grating embedded with lumps of melted fuel?

The images were the first of possible nuclear fuel debris at the nuclear plant since the Great East Japan Earthquake and tsunami caused the triple meltdown there in March 2011.

 

Sasori (Scorpion), an investigative robot, is expected to be sent in the containment vessel of the No. 2 reactor of the Fukushima No. 1 nuclear power plant in February.

 

High radiation levels have prevented workers from entering the No. 2 reactor, as well as the No. 1 and No. 3 reactors at the plant.

A number of problems have hampered investigations by robots into the location of melted fuel at the No. 1 and No. 3 reactors.

http://www.asahi.com/ajw/articles/AJ201701310073.html

 

 

February 1, 2017 - Posted by dunrenard | Fukushima 2017 | Fukushima Daiichi, Melted Fuel, reactor 2