Fukushima Daiichi nuclear plant damage caused by March 11, 2011 tsunami. Source: TEPCO
March 11, 2011 is a day most of us living in Japan at the time will remember for the rest of our lives.
At 2.46 p.m. a magnitude-9 earthquake struck 72km (45 miles) off the northeast coast of Japan, causing local damage as well as high-rise buildings 770km from the epicenter down in Osaka to sway for minutes. But the real destruction occurred an hour later when a tsunami came roaring in and devastated much of the coastline, sweeping inland as far as10km and reaching a run-up height of 39 meters (128 feet) in some areas.
The third whammy became known that night after it was announced that the tsunami had knocked out the electric power and backup generators at
In the days following, there were hydrogen explosions in some of the reactor buildings, and much later we learnt three of the six reactors in the plant had indeed suffered partial meltdowns due to cooling system failures.
Now, on the fifth anniversary of what is known here as the Great East Japan Earthquake, how much progress has TEPCO and the government made in dealing with what was fundamentally a man-made disaster?
The answer is they continue to face the same four huge challenges they grappled with in 2011: dealing with contaminated water that has grown into a million-ton headache; locating and somehow retrieving the molten fuel debris; removing spent fuel rods from the damaged reactor storage pools; and disposing of millions of cubic meters of radioactive waste.
Most evident of these challenges is the contaminated water. Cooling water must be continuously circulated through the damaged reactors Units 1, 2 and 3, where nuclear fuel has melted through at least the inner containment vessels. Consequently, the cooling water injected into the reactor becomes contaminated and finds its way down into the turbine basements adjacent to each reactor; there, it mixes with incoming ground water to greatly magnifying the problem.
Some of the pooled water is partly decontaminated, cooled and recirculated through the reactors again, the rest is treated and pumped out and stored in tanks to prevent it flowing into the Pacific Ocean.
TEPCO water tanks can be seen everywhere inside and outside the crippled plant.
Naohiro Masuda, TEPCO’s Chief Decommissioning Office, told the foreign press in Japan March 2nd that there are over 1,000 such storage tanks located inside and outside the plant, each holding as much as 1,000 cubic tons of treated water. And with groundwater streaming in at 150 cubic tons a day, a new tank is being added weekly.
The stored water, while filtered and largely decontaminated, still contains tritium—radioactive hydrogen, which can cause cancer if ingested.
“Tritium is very difficult to remove,” said Masuda. He added that the Ministry of Economy, Trade and Industry (METI) has “established a task force to look into the problem, and we will work with them on this.”
One possible option, he noted, was using evaporation to get rid of the water, which would presumably leave the Tritium behind for collection and storage.
Though 150 tons of inflowing groundwater may sound enormous, this is actually down from a previous 400 tons that streamed in daily. TEPCO achieved the reduction by building a bypass system that pumps up the groundwater on the landside of the plant, filters and checks it, then dumps it into the sea.
More spectacularly, the company has completed construction of an Ice Wall around the perimeter of the plant. I've covered that innovative feat of engineering here.
