On Fukushima Daiichi

This article has been written by fellow Kiwi, Kevin Hester who has been researching the events at Fukushima.

Fukushima Daiichi Unit 4 Fuel Pool Threats

by Kevin Hester.

The operator of Japan’s crippled Fukushima nuclear plant is preparing to remove 400 tons of highly irradiated spent fuel from a damaged reactor building, a dangerous operation that has never been attempted before on this scale.

More than 1,300 used fuel rod assemblies packed tightly together need to be removed from a building that is vulnerable to collapse, should another large earthquake, Typhoon or other natural event hit the area.

Each fuel rod assembly weighs about 300 kilograms and is 4.5 meters long. There are 1,331 of the spent fuel assemblies and a further 202 unused assemblies are also stored in the pool, .

During the removal process there is a risk of an inadvertent criticality if the bundles are distorted and get too close to each other. Under normal circumstances the fuel assemblies would be removed by computer controlled robotics and overhead cranes.

As a result of the post tsunami power failure,meltdowns and subsequent Hydrogen explosion the Building suffered catastrophic damage to its control systems and this process will have to be carried out in a manual process with ad-hoc equipement.Previously it was a computer-controlled process that memorised the exact locations of the rods down to the millimeter and now they don’t have that.

The fuel assemblies have to be first pulled from the racks they are stored in, then inserted into a heavy steel chamber. This operation takes place under water before the chamber, which shields the radiation pulsating from the rods, can be removed from the pool and lowered to ground level. Corrosion from the salt water introduced to the pools during the catastrophic days after the Tsunami will have also weakened the assembly housings and the zirconium tubes that contain the Uranium.Because some of the fuel has been used in the reactor the spent fuel rods contain plutonium that is formed during the later stages of a reactor core’s operation.

Fukushima Daiichi is pre-critical.

The spent fuel ponds in Unit four are teetering on the brink of Collapse. The feat of manually removing the Fuel assemblies has never been attempted before and there is a very high chance that some of the assemblies have been damaged.

The building housing these pools, located 30m above the ground, is on a lean and Tepco's own attempts to cool the rampant cores may have underminded the structural integrity of the building.

We are fast approaching a potentially apocaliptic moment in Human History. Heroic staff at the plant are going to need to risk all for us and the planet is going to have to be very,very lucky.

This is what the Nuclear Industry has led us to.

Potential Armageddon.