How dangerous is the Fukushima plant?

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

Proper equipment has now replaced the staggered plastic hoses joined by duct tape and a rat-infested outdoor electrical panel, which caused blackouts. Radiation levels have decreased, allowing workers and visitors to wear regular surgical clothing and masks in most areas.

But inside the plant, the danger is still hidden. Officials do not know exactly how long the cleanup will take, whether it will be successful and what the land where the plant sits may be.

Journalists from The Associated Press have recently visited the plant to document the progress in its cleaning on the tenth anniversary of the collapse and the challenges ahead.

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WHAT HAPPENED 10 YEARS AGO?

After a magnitude 9.0 earthquake on March 11, 2011, a 17-meter-high tsunami crashed into the coastal plant, destroying its power and cooling systems and causing damage to reactors no. . 1, 2 and 3.

The other three reactors at the plant were offline and survived, although a fourth building, along with two of the three molten reactors, had hydrogen explosions, emitting massive radiation and causing long-term pollution in the area.

The plant’s operator, Tokyo Electric Power Co., says the tsunami could not be predicted, but reports from government and independent investigations and recent court rulings described the plant’s disaster as a result of negligence. security and lax surveillance. by regulators and collusion.

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WHAT IS INSIDE THE BOTTOM REACTORS?

There are about 900 tons of molten nuclear fuel inside the three damaged reactors, and their disposal is a daunting task that officials say will take between 30 and 40 years. Critics say he is too optimistic.

Separate efforts to remove spent fuel from the cooling pools inside the reactor buildings were hampered by heavy radiation and debris and have been delayed by up to five years. If the plant’s pools lose cooling water in another major earthquake, the exposed fuel rods could heat up quickly and cause even worse thawing.

The molten cores of units 1, 2, and 3 mostly fell to the bottom of their primary containment vessels, some penetrating and mixed with the concrete base, making removal extremely difficult.

Remotely controlled robots with cameras have only provided a limited view of melted fuel in areas still too dangerous for humans.

The head of the plant, Akira Ono, says the inability to see what is happening at the reactors means details about the melted fuel are still unknown.

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ARE THERE UNDERGROUND LEAKS?

Since the disaster, contaminated cooling water has constantly escaped from the damaged primary containment vessels in the basements of the reactor building, where it mixes with the infiltrating groundwater. The water is pumped and treated. The part is recycled as cooling water, with the rest stored in 1,000 huge tanks that pile up the plant.

At the start of the crisis, highly polluted water leaking from damaged basements and maintenance ditches escaped into the ocean, but major leak points have been closed, according to TEPCO. The tons of contaminated sandbags used to block leaks at the start of the disaster are kept in two basements.

Small amounts of radiation have continued to seep into the sea and elsewhere through underground passages, even though the current amount is small and fish caught on the coast are safe to eat, scientists say.

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WHAT WILL HAPPEN TO STORED RADIOACTIVE WATER?

The 1,000 tanks were filled with treated, but still radioactive, water on the plant’s workers and visitors.

TEPCO says the storage capacity of 1.37 million tonnes of tanks will be full by 2022. The recommendation of a government group that the release of water into the sea will face fierce opposition from local residents, especially of fishermen concerned about further 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 by up to a third of what it used to be through a series of measures.

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WHAT IS VISITING THE PLANT LIKE?

The first thing visitors see is an elegant office building that houses the TEPCO dismantling unit.

In another building, plant workers – about 4,000 a day now – undergo automated security checks and radiation measurements.

Because radiation levels have dropped significantly after decontamination, only complete protective equipment is needed at some sites on the plant, including the molten reactor buildings and their surroundings.

On a recent visit, AP reporters wore partial protective gear to cover an area with little radiation: helmet, double socks, cotton gloves, surgical masks, goggles and vest with personal dosimeter.

In a shared storage pool complete protective equipment was needed, meaning a full hose, a full face mask, a headgear, triple socks and double rubber gloves, where the collection was recently completed. reactor pool fuel location no.

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WHAT IS THE END?

A decade after the accident, Japan still has no plan to dump the molten fuel, debris and highly radioactive waste from the plant. The technology is also not advanced enough to manage waste by reducing its toxicity.

TEPCO says it must dispose 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 waste.

There are approximately 500,000 tons of radioactive solid waste, including contaminated waste and soil, water treatment sludge, landfills and other waste.

It is not clear what the plant will look like when the work is finished. Local officials and neighbors say they hope the complex will one day be an open space where they can walk freely. But there is no clear idea of ​​whether or when this can happen.

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