JAPAN - Tokyo Electric Power Co. said Monday that the first step in removing nuclear fuel bundles from a storage pool at the No. 4 reactor building of its Fukushima No. 1 nuclear power plant is under way.
Work to remove the first fuel bundle from a rack inside the pool started at 3:18 p.m., the company said.
It is the first full-scale work to remove damaged nuclear fuel bundles from any of the plant's four reactor buildings since the start of the nuclear crisis in March 2011.
The reactor decommissioning process has entered a new stage, with preparations set to begin for removal of fuel from storage pools in the Nos. 1 to 3 reactor buildings, where radiation levels are higher, and for the recovery of melted nuclear fuel, which will be the most difficult task.
In the No. 4 reactor building's pool, 1,533 fuel bundles, the largest number among the four reactors, were put in a storage pool to cool.
Fuel bundles removed from the reactor building's spent fuel storage pool will be placed in shipping caskets, which will be then stored in a pool elsewhere on the plant grounds.
TEPCO said the first casket arrived at a site near the No. 4 reactor building on Wednesday. After final checks, it was sunk in the water of the No. 4 building's storage pool at 12:30 p.m. Monday.
It is a milestone in work to decommission the reactors, which is expected to take up to 40 years.
Each fuel bundle is about 4.5 meters long. There are 1,533 fuel bundles in the pool of the No. 4 reactor building.
Of them, 1,331 are spent fuel, which emits strong radiation, and 202 are unspent fuel. It will take until the end of next year to remove all the fuel bundles.
In the current work, 22 unspent fuel bundles will be placed into the casket in two days, and the casket will be transported to a shared pool about 100 meters from the reactor.
TEPCO said it will take about a week to finish the process.
Each cylindrical casket is 5.5 meters long and 2.1 meters in diameter. One casket is capable of accommodating 22 fuel bundles.
Work to remove the nuclear fuel will be carried out by six engineers using an underwater camera while confirming whether there is any small debris near the fuel bundles.
Fuel bundles will slowly be pulled up one by one and then placed into the casket.
The Secretariat of the Nuclear Regulation Authority dispatched Masaya Yasui, director general for emergency response, to the site to observe and confirm that the removal is being properly done.
A TEPCO official said: "Experience from the work at the No. 4 reactor will surely be useful for removal work at the Nos. 1 to 3 reactors in the future. We'll take all possible measures to ensure success."