What power cuts could mean for Chernobyl’s nuclear waste

Unlike a working nuclear plant, which can use some of the electricity it generates to power its operations, the long-defunct Chernobyl plant in Ukraine is completely dependent on to external power sources.

So when that power goes out, as Ukrainian officials and the International Atomic Energy Agency say it’s done by the Russian military, problems can arise.

As of Wednesday Chernobyl, the scene of the worst nuclear disaster in history when one of its four reactors exploded and burned 36 years ago, is running mostly on power from diesel generators. A former longtime plant employee with knowledge of the conditions there said that some equipment also operates on battery power, and that fire suppression and radiation monitoring systems, have been affected. .

IEAE said Wednesday that it did not see a “serious safety impact” at the complex. But what if all these backups fail and Chernobyl is completely without power?

The Chernobyl plant came into operation in the late 1970s, with the completion of the first two reactors. By 1983, the third and fourth ships were in service, including the one destroyed three years later.

That accident, the result of an unadvised and misguided examination, killed more than two dozen people shortly thereafter, most from exposure to high levels of radiation. The burning reactor core produced a flurry of radioactive particles that spread across parts of Europe, and many others suffered long-term effects, including cancer, from exposure.

Pollution was worst in large parts of Ukraine and Belarus around the plant, which has been declared an “exclusion zone” and remains largely out of bounds. Villages and a city were forever abandoned.

The plant’s three remaining reactors were eventually shut down, the last time in 2000. Nuclear fuel has been removed from all of them, and turbines and other power-generating equipment has mostly been retired. removed.

When there is no operating reactor at the plant, there is no risk of core meltdown as if an operating plant loses power and is no longer able to circulate water through the reactor. This is what happened at Fukushima reactor in Japan in 2011when an earthquake and tsunami wipe out backup power systems.

But Chernobyl carries several other risks associated with the large amounts of nuclear waste on site.

The fuel inside the reactor is eventually used up and replaced. As is common practice in the nuclear power industry, the fuel removed from all four Chernobyl reactors over the years, more than 20,000 in total, is stored in pools of water that dissipate heat. released when the fuel decays radioactively. When the new fuel is removed from the reactor and is still highly radioactive, there is a lot of decomposition and therefore a lot of heat, so the plants need electricity to run the storage water circulation pump. , removing excess heat in the process.

If the water in the tanks gets too hot and boils, the fuel will come into contact with the air and could ignite. That is also one of the risks in the Fukushima disaster.

The IAEA says the spent fuel assemblies at Chernobyl are old enough and have decayed to the point where recirculation pumps are not needed to keep them safe.

“The heat load of the spent fuel tank and the volume of cooling water contained in the tank is sufficient to maintain efficient heat removal without the need for electricity,” the agency said.

Before Russia invaded Ukraine, workers had already begun moving some of these fuel clusters to long-term dry storage, which will begin operations in 2020. The fuel clusters are ready for dry storage when they have cooled enough to safely exposed to the air. .

The other major source of nuclear waste, unique to Chernobyl, is the remnants of the destroyed reactor itself. An estimated 200 tons of fuel is still there, in a lava-like mixture of molten concrete, sand and chemicals that was poured onto the reactor during the disaster.

This highly radioactive mixture was found throughout the remainder of the reactor, flowing through doors and drains and down stairs and other parts of the structure before hardening. Some of these fuel-containing materials are, as their name suggests, located in completely inaccessible places and can only be studied by studying them.

In the chaos, the ruins of the Chernobyl reactor were destroyed, with no cooling system to affect the power failure.

But in recent years there have been periods in which nuclear reactions have started spontaneously in the pockets of these fuel-containing materials, leading to a spike in radiation levels. They have been tracked and will have to be dealt with someday.

Without monitoring, for both humidity and radiation, workers won’t know if any new waves are happening. A former employee with knowledge of conditions at the plant said the ventilation system that helped control humidity had stopped working.

Since 2017, the destroyed reactor has been covered by a large dome-shaped structure, intended to confine the waste and protect against any radiation. The structure is also meant to allow waste removal work to begin for long-term storage, a process that is expected to take decades.

The facility was only licensed by the Ukrainian authorities last year, so work has only just begun. There are a number of large cranes and other specialized equipment to enable crews to work safely. Without power, most, if not all of that work, cannot proceed.

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