Almost exactly 34 years ago, an older-style Soviet nuclear reactor near Ukraine’s capital, Kiev, exploded and caught fire. Although this was not a nuclear explosion, but an “ordinary” chemical one, it still caused an impressive amount of damage! The fire burned for over a week. Unfortunately, this almost forgotten disaster has just struck a second time. 

What happened 34 years ago?

At the time Chernobyl was planned, the Soviet Union was not going to build more of its older style RBMK reactors. These were graphite moderated reactors which used graphite bricks to slow the neutrons enough to allow the nuclear reaction to continue. The RBMK reactor could run on natural (unenriched) uranium. The newer type of reactor (the VVER series) requires low-enriched uranium fuel, but has many more safety features than the older style. It uses water as the moderator, and this water is under greater pressure than in the RBMKs, improving thermal efficiency. 

The older RBMK reactors main advantage was that fuel rods could be replaced while the reactor was running. This allowed operators to replace fuel rods at a time when they contained the maximum plutonium. While the Soviet Union was building its nuclear weapons capacity, this was very important. Now that both Russia and the USA have enough nuclear warheads to destroy the planet several times over, producing plutonium has become less important. 

Thirty four years ago, while carrying out a test on the Chernobyl reactor, mistakes were made causing reactor temperature and pressure to spike so high that it exploded. When the superheated steam contacted the hot graphite, large volumes of hydrogen formed, causing a second, chemical explosion, and a fire. It took nine days to completely extinguish the fire. By then the fire’s heat had lofted radioactivity from the damaged reactor high in the sky.

After the fire was extinguished (which killed 54 firefighters), the wreckage was allowed to cool and then was encased in concrete to contain the radioactive reactor core. Many more people living nearby died young following exposure to the Chernobyl’s radioactive fallout. 

What happened now?

The recent event is a much more prosaic forest fire. However, this burned a forest near the Chernobyl power station, coming as close as one kilometre from the reactor. In fact, this forest died 34 years ago; the trees were killed by radiation. 

This forest died, but never decomposed. The trees did not rot and are still standing. Locally this is called the “zombie forest”. Underneath the normal accumulation of leaves, branches, pine cones and needles also resisted rotting. Clearly the agents of decomposition: insects, fungi, and bacteria, were killed by radioactivity, and replacements have been unable to move back in. 

The forest fire is still burning (April 28th), lifting the accumulated radioactive material high into the sky. The concentration of cesium 137, a highly radioactive substance, in and around Kiev, Ukraine, is now several hundred times higher than normal, and well above levels considered safe. 

Residents have been told to remain indoors to avoid spreading COVID-19. Now they are being warned to stay indoors to avoid breathing smoke from the fires. But they have not yet been told that the smoke is contaminated with radioactive cesium!

Why build nuclear?

Proponents of nuclear power tell us that nuclear electricity is almost carbon-free, safe, and cheap. The first statement is true. Although much carbon is emitted during construction from cement manufacture and steel smelting, over the half-century lifetime of a power plant this is trivial. 

They are safe – sort of. The likelihood of a serious accident is very small, but as we have seen from Chernobyl, and more recently, Fukushima, the damage done is huge and costly. As a result, insurance companies refuse to insure nuclear power plants; they simply cannot calculate the probability of an accident, or estimate the damage such an accident might cause. This means that nuclear power plants are actually insured by the taxpayer because the state pays for any clean-up or compensation. 

The cost of nuclear power comes in three parts. First, the cost of construction is high because of all the safety features which must be incorporated – containment structures, fast-reacting control systems, multiples of everything like pumps, motorized valves, safety from terrorist attack, protection against aircraft crashing (accidentally or deliberately) into them, and others. Second, is the cost of running the plant. That is actually pretty cheap. Mostly automated, only a small number of people are needed to run the plant. Relative to the huge amount of power produced, the cost of fuel is low.

However, a third cost is almost always omitted; disposing of the radioactive waste the plant generates. Initially, bundles of radioactive spent fuel rods are stored under water. This water dissipates the heat which continues to be produced. After a decade or so the heat production diminishes to rods can be transferred to dry storage. Eventually, the spent fuel rods are meant to be buried deep underground. Unsurprisingly, very few people want a radioactive dump site in their neighbourhood!

Another hidden issue is that spent fuel rods remain dangerously radioactive for 100,000 to 200,000 years, over ten times longer than the span of recorded human history! We do not have materials (stainless steel, ceramics, glass) guaranteed to remain totally intact for 10,000 years, let alone ten times longer. Even if we had a material which would last 10,000 years, instructions would have to be left for “somebody”, to re-package the wastes into new containers. 

What language would these instructions be in, and using what script? The language of Shakespeare, just 400 years old, is hard to understand. The language of Chaucer (700 years ago), verges on unintelligible, while the Old English of Beowulf (1000 years ago) is truly unintelligible . . . 

It is hardly surprising that nobody has attempted to estimate the cost of storing nuclear waste. And don’t forget the cost of insurance – down to the taxpayer . . . 

Unknown Unknowns

Nobody expected that a nuclear power plant, built in a technologically advanced country like Japan would be vulnerable to a tsunami. In fact, Fukuishima might not have been a disaster had the storage tank for its emergency diesel generator been better protected and located higher up. 

Nobody expected that Chernobyl would have delivered a 2nd damaging blow to Ukraine’s capital city 34 years after the initial explosion. 

Both of these fall into what Donald Rumsfeld, former US Secretary of Defense, called “unknown unknowns”. Are there more lurking in our nuclear power plants futures?

-Written by Peter Bursztyn

Nuclear Power – “Unknown Unknowns” Can Cause Trouble!
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