In the recent, often breathless, discussion of Russia’s attack on a nuclear power station in southern Ukraine, there hasn’t been much detailed information about Ukraine’s nuclear power program, one of the most advanced in the world.
Here are some facts about Ukraine nukes, drawn from various credible sources.
According to the World Nuclear Association, the country has 15 operating reactors at five sites around the country, ranging in vintage from 1980 to 2004. All are Soviet-designed pressurized light water reactors, known as VVER reactors. The designs are based on, and stolen from, Westinghouse PWR designs, to the point that for years wags have referred to the Russian VVERs as “Eastinghouse Reactors.”
The Ukraine reactors range in power from 440 MWe to 1000 Mwe. Total nuclear electric capacity is almost 14 GW, providing about half of the country’s electric power. The six-unit Zaporizhzhina, station in southern Ukraine, which the Russians attacked, is the largest nuclear power plant in Europe with totaling 5,700 MWe of capacity.
So far, there is no evidence that the Russians, which reportedly control the plants, although that isn’t clear, as it seems the Ukrainian plant operators are still running the plant. There is no evidence the Russian forces have any plans to shut the plant or disrupt the country’s power grid. That may become clearer later.
There has been much hand-wringing about comparing the Russian assault on the Ukrainian site to the 1986 catastrophe at Chernobyl, in Ukraine, when the Soviet plant exploded and sent radiation airborne over much of Europe. But there are significant differences that make the comparison unlikely.
The Chernobyl plant, also a Soviet design, was an RBMK, (reaktor bolshoy moshchnosty kanalny, high-power channel reactor) technology. It was a graphite-moderated, water-cooled design, also developed to produce weapons-grade plutonium. The key to Chernobyl was that the design of nuclear reaction was moderated with graphite, to slow down neutrons from the uranium to sustain a fission reaction. But it was cooled with water.
In conventional light-water reactors, water is both the coolant and the moderator.
The Soviet RBMK design had a positive void coefficient of reactivity, which means that when the plant loses cooling water, the nuclear fission reaction continues and the plant heats up uncontrollably. As a result of some off-the-wall experiments when the reactor was operating, Chernobyl exploded, a low-yield nuclear weapon.
That can’t happen when today’s light-water reactors, including all the Ukrainian plants, run into troubles, either internally, or externally by attacks by hostile forces (Russian troops?). When they lose colling water, the fission reaction halts. They can, when attacked and damaged, melt down (see Three Mile Island and Fukushima), but the widespread consequences are less than Chernobyl.
That doesn’t mean meltdowns at Ukrainian plants would be benign, or minimal. They would be large, but very likely nothing to match Chernobyl.
According to the World Nuclear Association, eight RBMK nuclear reactors continue to operate in Russia, after improvements to cooling systems and control rod upgrades.
As to Fukushima, the 2011 devastation caused by the enormous tsunami was a function of the poorly-designed early General Electric boiling-water reactors, which, for economic reasons, had less robust containment structures than the PWRs in Ukraine, and the location of the spent fuel cooling pools on top of the reactors was a factor. But the spread of radiation, although financially devasting in Japan, had far less global impact than Chernobyl.
But it would be a catastrophe nevertheless if Russia’s invasion of Ukraine resulted in nuclear meltdowns at any of the country’s nuclear plants. The political damage to Russia would be severe, although it’s not clear that Putin cares.
–Kennedy Maize