OKUMA, Japan >> A decade ago, a major tsunami hit the Fukushima Daiichi nuclear power plant. Three of its reactors have melted, leaving it looking like a bombed-out factory. Emergency workers risked their lives trying to prevent one of the worst nuclear crises in history from getting out of hand.
Adequate equipment has now replaced tattered plastic hoses attached with tape and an external control panel infested with rats, which has caused blackouts. Radiation levels have decreased, allowing workers and visitors to wear normal clothes and surgical masks in most areas.
But deep inside the plant, the danger is still hidden. The authorities do not know exactly how long the cleanup will take, whether it will be successful and what can happen to the land where the factory is located.
Journalists from The Associated Press recently visited the factory to document progress in cleaning it up on the 10th anniversary of the collapses and the challenges ahead.
WHAT HAPPENED 10 YEARS AGO?
After a magnitude 9.0 earthquake on March 11, 2011, a 56-foot-high tsunami struck the coastal plant, destroying its power supply and cooling systems and causing melts in reactors # 1, 2 and 3.
The plant’s three other reactors went offline and survived, although a fourth building, along with two of the three melted reactors, had explosions of hydrogen, expelling massive radiation and causing long-term contamination in the area.
The plant operator, Tokyo Electric Power Co., said the tsunami could not have been predicted, but reports from government and independent investigations and recent court rulings described the plant disaster as man-made and the result of negligent safety, negligent supervision by regulators and collusion.
WHAT IS WITHIN THE MELTED REACTORS?
About 900 tonnes of melted nuclear fuel remain inside the three damaged reactors, and removing it is a difficult task that officials say will take 30 to 40 years. Critics say this is too optimistic.
Separate efforts to remove spent fuel from the cooling pools inside the reactor buildings have been hampered by high radiation and debris and have been delayed for up to five years. If the plant’s pools lose cooling water in another major earthquake, the exposed fuel rods can overheat quickly and cause an even worse melt.
The melted cores in Units 1, 2 and 3 fell mainly to the bottom of their primary containment containers, some penetrating and mixing with the concrete foundation, making removal extremely difficult.
Remotely controlled camera robots provided only a limited view of the melted fuel in areas still very dangerous to humans.
The head of the plant, Akira Ono, says that the inability to see what is happening inside the reactors means that the details of the molten fuel are still largely unknown.
ARE THERE UNDERGROUND LEAKS?
Since the disaster, contaminated cooling water has been constantly escaping from the damaged primary containment vessels to the basements of the reactor building, where it mixes with the groundwater that penetrates. The water is pumped and treated. Part of it is recycled as cooling water, with the rest stored in 1,000 huge tanks filling the factory.
At the beginning of the crisis, highly contaminated water that leaked from damaged basements and maintenance ditches escaped into the ocean, but the main spill points were closed, TEPCO said. Tons of contaminated sandbags filled with material used to reduce cesium in the highly radioactive water at the start of the disaster remain in two cellars.
Small amounts of radiation continued to leak into the sea and elsewhere through underground passages, although the amount today is small and the fish caught off the coast are safe to eat, scientists say.
WHAT WILL HAPPEN WITH STORED RADIOACTIVE WATER?
The 1,000 tanks were filled with towers of treated, but still radioactive, water over workers and visitors to the factory.
TEPCO says that the storage capacity of 1.37 million tonnes of the tanks will be full by 2022. The recommendation of a government panel that water should be released into the sea is facing strong opposition from local residents, especially fishermen concerned with further damage to the area’s reputation. The decision on this recommendation is pending.
TEPCO and government officials say that tritium, which is not harmful in small amounts, cannot be removed from water, but all other isotopes selected for treatment can be reduced to safe levels for release.
TEPCO was able to reduce the amount of contaminated water to a third of what it used to be through a series of measures.
HOW IS IT VISITING THE PLANT?
The first thing visitors see is an elegant office building that houses the TEPCO decommissioning unit.
In another building, factory workers – about 4,000 a day now – undergo automated security checkpoints and radiation measurements.
As radiation levels have dropped significantly after decontamination, full protective equipment is only needed in some places on the plant, including in and around the melted reactor buildings.
On a recent visit, AP journalists donned partial protection equipment to cover a low-radiation area: helmet, double socks, cotton gloves, surgical masks, goggles and vest with a personal dosimeter.
Total protective equipment, which means overalls made of anti-scratch material, face mask, head cover, triple socks and double rubber gloves, were needed in a shared storage pool where the fuel reallocation of the reactor pool No. 3 was recently completed.
WHAT IS THE ENDGAME?
A decade after the accident, Japan still has no plan to dispose of the highly radioactive melted fuel, debris and waste from the plant. The technology is also not advanced enough to manage waste by reducing its toxicity.
TEPCO says it needs to get rid of water storage tanks to free up space at the plant so workers can build facilities that will be used to study and store molten fuel and other debris.
There are about 500,000 tonnes of radioactive solid waste, including contaminated soil and debris, water treatment sludge, scrap tanks and other waste.
It is unclear what the plant will look like when the work is completed. Local authorities and residents say they hope the complex will one day be an open space where they can walk freely. But there is no clear idea if or when this can happen.