Antinuclear

Australian news, and some related international items

The Risks of Russian Attacks near Ukraine Nuclear Power Plants

The Risks of Russian Attacks near Ukraine Nuclear Power Plants, Commercial plants have built-in safety systems, but aren’t designed with warfare in mind. Scientific American By Andrea Thompson on March 4, 2022     People around the world watched via livestreamed security camera as Russian forces attacked and took over Ukraine’s Zaporizhzhia nuclear power plant—the largest in Europe—on Friday morning local time. Amid the shelling and gunfire, a fire broke out at a training facility in the complex and was later extinguished, according to news reports. The incident raised alarm among world leaders and nuclear experts about the potential for purposeful or accidental reactor damage that could cause radiation leaks or, in a worst-case scenario, reactor core meltdowns.

Rafael Grossi, director general of the International Atomic Energy Agency (IAEA), told the United Nations Security Council that the plant’s operations were normal after the attack and has said that no radioactive material was released. But he and other nuclear experts have warned that there is a danger of accidents there and at other nuclear plants in Ukraine as the conflict continues.

Scientific American spoke with Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists, to explain the concerns about such facilities during wartime and to talk about some of the safety measures that are in place.

The six reactors at Zaporizhzhia are called VVER-1000s, and they are cooled and moderated by light [ordinary] water. So in that respect, they’re similar to U.S. pressurized water reactors. They are somewhat more advanced models than the earlier versions of [this type of reactor], so they do have some features that are more in line with modern safety philosophy—but not entirely. …………

These [Zaporizhzhia reactors] were designed in the Soviet Union, and they date as far back as the early 1980s. So they are past their expiration date, but the Ukrainians extended their licenses………..

The big danger in any nuclear reactor is that somehow cooling of the fuel is disrupted, because without enough cooling, the fuel will heat up to the point where it can destroy itself……    In addition, these plants store their spent nuclear fuel on-site—and some of that fuel is stored in cooling water, which also has to be replenished with pumps………

In addition to a pipe break, you can have a loss of power, which is what affected Fukushima. These plants normally draw electricity from the grid to operate their systems, and if that’s interrupted, they have to rely on backup power with emergency diesel generators. …….

……f you want to potentially seriously damage the plant, you don’t have to go after the containment building, which is the hardest part. There are other systems that are not as well protected. But even those containment buildings are not necessarily able to withstand certain types of military attack. Even if they are not breached, they can spall, and you can have concrete falling down onto the reactor vessel. Or just strong vibrations might also cause damage……….

The cost of hardening commercial nuclear power plants so that they might survive a military onslaught is probably prohibitive……..

 In the worst case, if you have an unmitigated loss of cooling capability, the nuclear fuel can overheat and melt and burn through the steel reactor vessel that holds it and drop to the floor of the container. And in that case, the containment is the only remaining barrier between the radioactive material in the reactor and the environment. It’s designed to withstand certain types of events but not others.
……

if multiple reactors are affected at the same time, if the spent fuel is damaged, if the containment is mechanically breached, then all bets are off……

… having well-rested operators is critical because the tasks they have to perform are complex, and they need to be alert. You have to ensure that fatigue is being monitored. If there’s a plant staff, and they’re not getting any relief, and they can’t go home, and they’re working under duress, it’s a dangerous combination. There will have to be measures for that………..  https://www.scientificamerican.com/article/the-risks-of-russian-attacks-near-ukraine-nuclear-power-plants1/

March 7, 2022 - Posted by | Uncategorized

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