Do We Need a New Chernobyl?

Andrey Allakhverdov

What’s happened?

Thirty-five years on, while scientists are still studying the consequences of the Chernobyl disaster, governments and companies are laying foundations for new nuclear accidents.

Ranked as the worst nuclear disaster to date, Chernobyl is a quarter of a century older than Fukushima. But it still presents challenges that authorities haven’t figured out how to address. Technology to deal with the radioactive fuel that remains in the reactor doesn’t yet exist. A new sarcophagus was added in 2016 in an attempt to buy some time to invent new approaches.

Why does it matter?

Around five million people in Ukraine, Belarus and Russia still live in territories that are officially recognised as contaminated. People who live here constantly receive new doses of radiation, as documented in joint research produced by Greenpeace and Ukranian scientists. Methods to deactivate the contaminated areas either don’t exist, or – where there are usable technologies – the states do not have resources to deploy them.

Meanwhile, Chernobyl from time to time reminds us that it is still here and is still dangerous. And with climate change the danger only grows.

Last year huge forest fires raged in the exclusion zone. It was not for the first time. In 35 years, fires have broken out in the exclusion zone more than 1,500 times. But due to the unusual drought caused by climate breakdown, it was the largest fire since the exclusion zone was set up, covering a third of this sensitive area. At one point, only a kilometer separated the edge of the fire and the newly built sarcophagus.

Plumes from the fire stretched for tens of kilometres towards Ukraine’s capital Kiev, fuelling fears that the smoke particles may raise radiation levels in the city. Fortunately, this did not happen, the radiation outside the exclusion zone remained at a low level deemed acceptable by the authorities. But firefighters had to work in the most contaminated areas of the zone where, according to press reports, radiation levels exceeded the background level by 16 times.

What do the scientists say?

“Unfortunately, we have very little information on the radiological environmental hazards of fires in radioactively contaminated areas,” says Professor Valery Kashparov, head of the Ukrainian Research Institute of Agricultural Radiology.

“Fires pose the greatest problem mainly from the point of view of the radiation exposure of firefighters. For them the danger is the highest. The greatest danger may be related to the inhaled dose, due to the intake and the entry of radionuclides into the lungs.”

What needs to happen?

Firefighters need to have complete information on the radiation risks before they go to the contaminated areas. But the last study on this issue was done 20 years ago and since then the natural conditions have shifted. The climate crisis is causing more frequent droughts, ecosystems have changed and each fire has had an impact on the local environment.

This year, when the weather conditions allow it, the Institute with support from Greenpeace, will study a range of parameters that influence radiation doses during the fires.

“The main task of the experiment is to estimate the expected doses for firefighters – because this is the most critical group that can receive the highest inhalation doses during a fire. We will then work out recommendations to minimise the risk,” says Professor Kashparov.

The bigger picture

The fire experiment will provide the data needed to assess risks faced by firefighters. That’s crucial for protection of the individuals, their families and colleagues. But this is only one of the dangers caused by the nuclear disaster 35 years ago that still has to be dealt with. And who knows how much more scientists will discover in the future.

Even countries that have survived the horrors of this disaster on their soil continue to cling tenaciously to nuclear power. A new nuclear power plant is being built right now in Belarus. Russia not only builds stationary ones, but has launched a floating nuclear power plant – the ‘Akademik Lomonosov’ operated by Rosatom was immediately dubbed a ‘floating Chernobyl’. More than 30 countries around the world are still operating nuclear plants.

What’s needed now?

What the world really needs is for governments and companies to stop introducing new nuclear risks when we still cannot cope with the existing ones. The only way to do this is to phase out nuclear energy and switch to renewables as soon as possible.

(Andrey Allakhverdov is a media coordinator at Greenpeace Russia. Article courtesy: Greenpeace.)

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‘It’s Like the Embers in a Barbecue Pit.’ Nuclear Reactions are Smoldering Again at Chernobyl

Richard Stone

Thirty-five years after the Chernobyl Nuclear Power Plant in Ukraine exploded in the world’s worst nuclear accident, fission reactions are smoldering again in uranium fuel masses buried deep inside a mangled reactor hall. “It’s like the embers in a barbecue pit,” says Neil Hyatt, a nuclear materials chemist at the University of Sheffield. Now, Ukrainian scientists are scrambling to determine whether the reactions will wink out on their own—or require extraordinary interventions to avert another accident.

Sensors are tracking a rising number of neutrons, a signal of fission, streaming from one inaccessible room, Anatolii Doroshenko of the Institute for Safety Problems of Nuclear Power Plants (ISPNPP) in Kyiv, Ukraine, reported last week during discussions about dismantling the reactor. “There are many uncertainties,” says ISPNPP’s Maxim Saveliev. “But we can’t rule out the possibility of [an] accident.” The neutron counts are rising slowly, Saveliev says, suggesting managers still have a few years to figure out how to stifle the threat. Any remedy he and his colleagues come up with will be of keen interest to Japan, which is coping with the aftermath of its own nuclear disaster 10 years ago at Fukushima, Hyatt notes. “It’s a similar magnitude of hazard.”

The specter of self-sustaining fission, or criticality, in the nuclear ruins has long haunted Chernobyl. When part of the Unit Four reactor’s core melted down on 26 April 1986, uranium fuel rods, their zirconium cladding, graphite control rods, and sand dumped on the core to try to extinguish the fire melted together into a lava. It flowed into the reactor hall’s basement rooms and hardened into formations called fuel-containing materials (FCMs), which are laden with about 170 tons of irradiated uranium—95% of the original fuel.

The concrete-and-steel sarcophagus called the Shelter, erected 1 year after the accident to house Unit Four’s remains, allowed rainwater to seep in. Because water slows, or moderates, neutrons and thus enhances their odds of striking and splitting uranium nuclei, heavy rains would sometimes send neutron counts soaring. After a downpour in June 1990, a “stalker”—a scientist at Chernobyl who risks radiation exposure to venture into the damaged reactor hall—dashed in and sprayed gadolinium nitrate solution, which absorbs neutrons, on an FCM that he and his colleagues feared might go critical. Several years later, the plant installed gadolinium nitrate sprinklers in the Shelter’s roof. But the spray can’t effectively penetrate some basement rooms.

Chernobyl officials presumed any criticality risk would fade when the massive New Safe Confinement (NSC) was slid over the Shelter in November 2016. The €1.5 billion structure was meant to seal off the Shelter so it could be stabilized and eventually dismantled. The NSC also keeps out the rain, and ever since its emplacement, neutron counts in most areas in the Shelter have been stable or are declining.

But they began to edge up in a few spots, nearly doubling over 4 years in room 305/2, which contains tons of FCMs buried under debris. ISPNPP modeling suggests the drying of the fuel is somehow making neutrons ricocheting through it more, rather than less, effective at splitting uranium nuclei. “It’s believable and plausible data,” Hyatt says. “It’s just not clear what the mechanism might be.”

The threat can’t be ignored. As water continues to recede, the fear is that “the fission reaction accelerates exponentially,” Hyatt says, leading to “an uncontrolled release of nuclear energy.” There’s no chance of a repeat of 1986, when the explosion and fire sent a radioactive cloud over Europe. A runaway fission reaction in an FCM could sputter out after heat from fission boils off the remaining water. Still, Saveliev notes, although any explosive reaction would be contained, it could threaten to bring down unstable parts of the rickety Shelter, filling the NSC with radioactive dust.

Addressing the newly unmasked threat is a daunting challenge. Radiation levels in 305/2 preclude getting close enough to install sensors. And spraying gadolinium nitrate on the nuclear debris there is not an option, as it’s entombed under concrete. One idea is to develop a robot that can withstand the intense radiation for long enough to drill holes in the FCMs and insert boron cylinders, which would function like control rods and sop up neutrons. In the meantime, ISPNPP intends to step up monitoring of two other areas where FCMs have the potential to go critical.

The resurgent fission reactions are not the only challenge facing Chernobyl’s keepers. Besieged by intense radiation and high humidity, the FCMs are disintegrating—spawning even more radioactive dust that complicates plans to dismantle the Shelter. Early on, an FCM formation called the Elephant’s Foot was so hard scientists had to use a Kalashnikov rifle to shear off a chunk for analysis. “Now it more or less has the consistency of sand,” Saveliev says.

Ukraine has long intended to remove the FCMs and store them in a geological repository. By September, with help from European Bank for Reconstruction and Development, it aims to have a comprehensive plan for doing so. But with life still flickering within the Shelter, it may be harder than ever to bury the reactor’s restless remains.

(Richard Stone is senior science editor at the Howard Hughes Medical Institute’s Tangled Bank Studios in Chevy Chase, Maryland. Article courtesy: Sciencemag.org.)

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35 Years After Chernobyl’s Meltdown, the Fallout of Radiation Continues

Katie MacBride

The fallout from Chernobyl is both vast and ongoing. In 1986, the Chernobyl Nuclear Power Plant accident killed two workers at the plant immediately, and in the following days and weeks, the fatalities rose. Today, two studies show how the accident’s effects continue to manifest in ripples of illness and death.

In one study, researchers based in the United States and Ukraine looked at genetic mutations in the children of people who had been exposed to radiation; in the other, scientists evaluated the genomic profile of cancerous tumors removed from people exposed to the blast’s radiation.

The reason why the scientists are looking again at the fallout from the explosion today is not out of morbid curiosity. Rather, these studies are a bid to better understand how genetic material may be changed by radiation — and how exposure manifests in the genetics of future generations, too. With ongoing threats to staff and residents around the Fukushima Daiichi nuclear power plant, and 440 active nuclear reactors around the globe, it’s crucial to understand the long-term, and generational effects, of ionizing radiation.

What happened at the Chernobyl Nuclear Power Plant?

Shortly after midnight on April 26, 1986, a nuclear power plant 2 miles from the city of Pripyat, in what was then the Soviet Union (now Ukraine), started to malfunction. Reactor 4 of the Chernobyl Nuclear Power Plant was in trouble. The reactor and its emergency cooling core had been shut down the day before for routine maintenance and tests. But the test had to be postponed. Despite the delay, communication and safety protocols lapsed, and, the cooling core was kept offline. Steam started to build in the cooling pipes, causing a power surge the plant’s engineers couldn’t shut down.

The explosions began at 1:23 am, spreading a toxic cloud full of radioactive debris into the air above the plant. The explosion also caused a fire, which tore through another building and further spread the radioactive cloud across the surrounding communities. Over the next several hours, two plant workers died of acute radiation poisoning. The people of Pripyat, meanwhile, started vomiting and reporting a metallic taste in their mouths. They weren’t evacuated until more than 24 hours after the plant blew up.

What does Chernobyl radiation do to your body?

Exposure to even low doses of ionizing radiation can damage the body in any number of ways, but one of the biggest concerns is cancer. This happens because ionizing radiation damages DNA. It is why Marie Curie, the famous scientist who discovered both polonium and radium, two radioactive elements, died of cancer. It is also why you need to wear a lead apron when you get an X-Ray to protect your body.

The severity and kind of illness people develop from ionizing radiation depends on several factors, including:

• How much radiation they were exposed to
• What tissue in the body was exposed to the radiation
• Length of exposure (and/or the number of times exposed)
• Vehicle for exposure — in other words, eating contaminated food, breathing it in, touching a radioactive element, etc)

What diseases did Chernobyl cause?

The World Health Organization estimates that the health of 5 million people in the former USSR was affected by the disaster in some way By other estimates, as many as 800,000 people in Belarus, a neighboring state, were affected by the radiation alone.

Some of the workers drafted to do the initial cleanup later developed leukemia. Lindsay Morton is a Senior Investigator with the National Institute of Health and an author on one of the new studies examining Chernobyl. She tells Inverse that people in the surrounding areas were likely exposed to radiation from Chernobylthrough “leafy greens and milk.” The radiation-contaminated plants, including the plants farm animals ate, and therefore any animal products those animals produced were contaminated, too.

In the years after the explosion, incidences of thyroid cancer skyrocketed in the surrounding areas. “Iodine is one of the building blocks in thyroid hormones,” Morton explains, “and the body can’t distinguish between iodine and radioactive iodine. So when a person ingests radioactive iodine, it concentrates in the thyroid.”

The rates of thyroid cancer increased the most in children, a morbid finding that suggests, according to one study, that children under the age of five are “particularly vulnerable to the effects of radiation.”

Do mutations from radiation exposure pass down?

There is some good news from the new studies. The first study, published Thursday in Science, found that parents who had been exposed to radiation from the accident were no more likely to have children with so-called de novo genetic mutations than parents who experienced no radiation exposure.

De novo mutations are genetic alterations that happen after conception and are not inherited directly from one’s parents; rather, they may be the result of other factors, like age, environment, health, and other things that affect the biology of cells.

Stephen Chanock, one of the researchers on the new papers, tells Inverse that typically, you expect to see between 50 and 100 de novo mutations occur in any conception. Chanock is the Director of the Division of Cancer Epidemiology & Genetics at the National Institute of Health. In this study, Chanock and his colleagues couldn’t find any significant difference in the germline of parents who had been exposed to radiation and those who hadn’t.

“In science, it’s very difficult to prove a negative,” he says. “We modeled it many, many different ways, and we didn’t find any significant differences.”

Chanock and his colleagues note in the study that the children were conceived “months or years” after their parents had been exposed. As a result, the findings may not apply to children conceived closer to the moment when their parents are exposed to ionizing radiation.

How does radiation cause tumors?

The second study analyzed thyroid tumors, thyroid tissue, and blood collected from people who were exposed to radiation from Chernobyl, and then compared these samples to equivalent issues and blood taken from people who were not exposed to radiation. The comparison reveals a significant dose-dependent increase in double-strand DNA breaks among the exposed group.

Why it matters — Sometimes, when there’s a clean, double-strand DNA break, the cell can repair it quickly, Morton says. Other times, the repair job is less clean and efficient. When something like ionizing radiation is responsible for a double-strand DNA break, she says, there can be multiple double-strand DNA breaks.

“The DNA is broken in one place, and you have two of part A. Then the DNA is broken in another place, and you have two of part B.” Instead of the As being rejoined and the Bs being rejoined, Morton says, “A and B are joined. And that makes what’s called a gene fusion. The cell has fused the wrong parts back together.”

Picture two shoelaces. One gets split in half and the other gets split in half. But instead of reconnecting each shoelace with its former part, you swap them. Half of shoelace 1 is now fused with shoelace 2, and vice versa. Not such a big deal when we’re talking about shoelaces. But with DNA, which has important instructions for your cells? That kind of mismatch, or gene fusion, is likely to cause some problems.

The higher dose of radiation the person had been exposed to, the more double-strand DNA breaks the researchers found. The association was clear, Morton says.

“We measured DNA double-strand breaks in multiple ways. And all of them showed consistent, clear, strong associations with radiation.”

Previous studies have shown double-strand DNA breaks in the blood of people recently exposed to ionizing radiation. But “double-strand DNA breaks have never actually been linked to a human tumor before,” Morton says.

Taken together, these findings have important consequences for how we understand ionizing radiation and how to protect ourselves from it.

“There’s a bit of a debate in radiation science about whether very low doses of ionizing would cause damage,” Morton says. The linear relationship between dose-dependent exposure and double-strand DNA breaks puts that question to rest.

(Katie MacBride is a health science journalist. Article courtesy: Inverse.)