The tsunami that came roaring in five years ago today to smash Japan’s northeast coast did far more damage than the magnitude 9 earthquake that set it in motion. The wall of water also knocked out the power and backup systems of Tokyo Electric Power Company’s (TEPCO) Fukushima Daiichi Nuclear Plant and triggered the second worst nuclear accident in history—the worst being Chernobyl, the third, Three Mile Island.
Without power, the understandably panicked Fukushima maintenance staff was unable to pump cooling water through three of the reactor cores still online. The water covering the uranium rods boiled and evaporated, the uncovered rods overheated, and meltdowns of varying degrees followed.
It took months of struggle and setbacks by the now mostly forgotten brave workers to bring the situation under some kind of control.
Today, all the reactors are in cold shutdown. Temperatures at the bottom of each damaged pressure vessel that housed the fuel is now a reassuring 15 to 20 degrees C, with water being injected at a rate of 4.5 cubic meters an hour.
Nevertheless, the reactor buildings have been damaged by hydrogen explosions, three reactors are holed and leaking, and the water-cooling and filtering system is vast and complex and in the past was prone to disruptions and leaks. So though TEPCO now has back-up systems galore at the ready, no one should think another calamity couldn’t strike again.
On the bright side, the daily inflow of groundwater into the reactor and turbine building basements has been cut to 150 cubic tons from 400 tons and the Ice Wall is ready to switch on and will hopefully decrease the inflow much more.
Consequently, TEPCO and the government are now considering how to tackle the most difficult and hazardous part of decommissioning the broken plant: removal of the highly dangerous melted fuel and debris it’s come in contact with.
Satoru Toyomoto, a director in Japan’s Ministry of Economy, Trade and Industry (METI), updated the foreign press this month on the government’s newly revised 30/40-year Decommissioning Road Map. The aggressive mid-term schedule calls for the removal of spent-fuel rods from the cooling pool in Reactor Unit 1 as early as the second half of 2017. Then “around two years from now,” a decision is to be made on what methods to use for removing the melted fuel debris, while 2021 is earmarked for the retrieval work to begin.
One problem here is that TEPCO engineers can’t get close to the reactors to gauge the extent of the damage first hand, on account of the lethal radiation. Consequently, they don’t have a clear idea how much of the fuel has melted, whether or not it has burnt its way through both the reactor and containment vessels, and where it might have ended up.
But they are gradually building up a picture based on data, photographs and 3D scans obtained by an army of robots (supplied by cooperating domestic and overseas companies and institutes) being sent into the reactor buildings.
In addition, TEPCO has added muon ray detectors to this arsenal of helpers. This advanced technology was developed by scientists from Japan’s High Energy Accelerator Research Organization (KEK) and the International Research Institute for Nuclear Decommission (IRID).
Muons are sub-atomic particles spewed out by our sun and far distant stars that constantly bombard the earth, normally passing harmlessly through most obstacles including we humans. But they can be deflected by heavy elements like uranium. By detecting changes in the paths of the muons entering and exiting the reactors, the scientists believe they can work out where melted fuel debris is located.
To sum up, five years on since the disaster, the situation is far from rosy both inside and outside the damaged Daiichi plant site, nevertheless, progress is being made to turn things around.
Throughout Fukushima Prefecture small mountains composed of millions of tons of bagged radioactive topsoil and debris can be seen stored in the open, while thousands of evacuated residents are still waiting to return to their towns and villages. At the same time, this massive cleanup has resulted in bringing down radiation levels. People are gradually returning home, and the government says it’s on target to achieve a safe outdoor exposure level of 0.23 microsieverts per hour in many areas.
TEPCO workers’ living conditions have improved. Hot meals are now served regularly and there’s even a Lawson’s konbini store to bring a neighborhood touch to an otherwise bleak environment.
So decommissioning work is advancing—albeit slowly, as outlined above (and as I've written on this blog site). And for this, at least, we must thank the 7,000 workers toiling daily in conditions ranging from the unpleasant to the dangerous in order to deal with what is a natural disaster turned manmade catastrophe. Domo arigato gozaimasu.
This first appeared on my Forbes blog site: http://www.forbes.com/sites/jboyd