How dangerous is the Fukushima nuclear plant today?

OKUMA, Japan (AP) – A decade ago, a massive tsunami crashed on the Fukushima Daiichi nuclear power plant. Three of its reactors melted, leaving it to look like a bombed-out factory. Emergency workers risked their lives trying to prevent one of the worst nuclear crises in history from escalating.

Appropriate equipment has now replaced ragged plastic hoses, held together with tape and a rat-infested outdoor power supply, which has caused disruptions. Radiation levels have dropped, allowing workers and visitors to wear regular clothing and surgical masks in most areas.

But deep inside the plant, the danger still lies. Officials do not know exactly how long the cleaning will take, if it will be successful and what could become of the land on which the plant is located.

Journalists from The Associated Press recently visited the plant to document progress in cleaning it up on the 10th anniversary of the crisis and the challenges ahead.

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WHAT HAPPENED IN 10 YEARS?

After a magnitude 9.0 earthquake on March 11, 2011, a 17-meter (56-foot) tsunami struck the coastal facility, destroying its power supplies and cooling systems and causing melting at reactors no. 1, 2 and 3.

The plant’s other three reactors were offline and survived, although a fourth building, along with two of the three melted reactors, exploded with hydrogen, emitting massive radiation and causing long-term contamination in the area.

The plant’s operator, Tokyo Electric Power Co., says the tsunami could not have been anticipated, but government and independent investigation reports and recent court decisions have described the plant disaster as man-made and due to negligence. safety, lax surveillance. by regulators and collusion.

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WHAT IS INSIDE FOUNDED REACTORS?

About 900 tons of molten nuclear fuel remain inside the three damaged reactors, and its removal is a daunting task that officials say will take 30-40 years. Critics say he is too optimistic.

Separate efforts to remove spent fuel from cooling tanks inside reactor buildings have been hampered by high radiation and debris and have been delayed by up to five years. If the plant’s tanks lose their cooling water in another major earthquake, the exposed fuel rods could quickly overheat and cause even more melting.

The molten cores in Units 1, 2 and 3 have mostly fallen to the bottom of their primary insulating vessels, some penetrating and mixing with the concrete foundation, making removal extremely difficult.

Remote-controlled robots with cameras provided only a limited picture of the molten fuel in areas still too dangerous for humans to access.

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.

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ARE THERE AN UNDERGROUND LEAKS?

Since the disaster, contaminated cooling water has consistently escaped from damaged primary insulation vessels in the basements of the reactor building, where it mixes with leaking groundwater. The water is pumped and treated. The piece is recycled as cooling water, and the rest stored in 1,000 huge tanks that crowd 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 drainage points were closed, says TEPCO. Tons of contaminated sandbags used to block leaks at the start of the disaster remain in two basements.

Small amounts of radiation have continued to flow into the sea and elsewhere through underground passages, although the amount today is small and fish caught off the coast can be eaten safely, scientists say.

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WHAT WILL HAPPEN WITH STORED RADIOACTIVE WATER?

The 1,000 tanks filled with treated but still radioactive water rise above the factory workers and visitors.

TEPCO says tank storage capacity of 1.37 million tonnes will be full in 2022. A government group’s recommendation that the water be released into the sea faces fierce opposition from locals, especially fishermen concerned with other areas. damage to the area’s reputation. A decision on this recommendation is pending.

TEPCO and government officials say tritium, which is not harmful in small amounts, cannot be removed from the water, but all other isotopes selected for treatment can be reduced to safe levels for release.

TEPCO has managed to reduce the amount of contaminated water to a third of what it was before through a series of measures.

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WHAT IS TO VISIT THE PLANT?

The first thing visitors see is an elegant office building owned by the TEPCO decommissioning unit.

In another building, factory workers – about 4,000 a day now – go through automated security checkpoints and radiation measurements.

Because radiation levels have dropped significantly after decontamination, full protective equipment is only needed in a few places in the plant, including in and around the molten reactor buildings.

During a recent visit, AP journalists wore partial protective equipment to visit an area with low radiation: a helmet, double socks, cotton gloves, surgical masks, goggles and a vest with a personal dosimeter.

A complete protective equipment, which means hazmat overalls, a full face mask, a head cap, triple socks and double rubber gloves, was necessary in a common storage pool, where the relocation of fuel from the reactor pool no.

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WHAT IS THE FINAL GAME?

A decade after the accident, Japan does not yet have a plan to dispose of highly radioactive molten fuel, debris and plant waste. Also, the technology is not yet 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 that workers can build facilities that will be used to study and store molten fuel and other debris.

There is approximately 500,000 tonnes of solid radioactive waste, including contaminated waste and soil, sewage sludge, scrap tanks and other waste.

It is not clear what the plant will look like when working there. Local officials and residents say they expect the complex to one day be an open space where they can walk freely. But there is no clear idea if or when this can happen.

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Tokyo correspondent Mari Yamaguchi has visited the Fukushima nuclear power plant nine times since 2012.