Did it smash any fuel assembly?

February 8, 2013

TEPCO accident causes new problem at Fukushima

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201302080063

THE ASAHI SHIMBUN

The operator of the Fukushima No. 1 nuclear plant has admitted dislodging broken equipment weighing 1.5 tons and sending it falling further into a pool where fragile nuclear fuel rods lie.

The debris is part of a heavy-duty hoist formerly used to move fuel assemblies within the No. 3 reactor building. The hoist collapsed into the pool after a hydrogen explosion in March 2011.

Until now, it lay only partially submerged and was believed to have done little damage to the fuel rods beneath.

But on Feb. 7, Tokyo Electric Power Co. officials said work a day earlier to shift an unrelated steel frame nearby caused "vibrations" which dislodged the hoist. It fell, disappearing beneath the water surface.

TEPCO now plans to drop a video camera into the pool to check whether the hoist has smashed fuel rods below.

Officials say 566 fuel assemblies are currently lying in the pool at the No. 3 reactor building.

They insisted there has been no significant change in radioactive concentrations measured in the pool and in the atmosphere since before the latest incident.

__________________________________________________________________________

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_120208_01-e.pdf

Possibility of Debris (Assumed to be the Fuel Handling Machine Mast) Sinking in the

Spent Fuel Pool at Debris Removal from the Upper Part of the Unit 3 Reactor

Building at Fukushima Daiichi Nuclear Power Station

February 8, 2013

Tokyo Electric Power Company

Before steel truss debris removal (Photo taken on February 4, 2013)

At the steel truss debris removal from the upper part of the spent fuel pool performed on February 6, 2013, the

debris assumed to be the fuel handling machine mast* which was present before the steel truss removal was

found to be missing in the image taken after the removal work. On February 7, we judged that there is a possibility

that the missing debris has sunk into the pool.

*Fuel handling machine mast: Extendable pole used to lift the grip up and down when moving the fuel assemblies (Length: Approx. 5-

23m, Weight: Approx. 1.5 tons)

Once the preparation is complete, we will investigate the condition of the sunken debris when we perform investigation of the inside of the spent fuel pool utilizing an underwater camera