On March 4th Putin's troops shelled Zaporizhzhia nuclear power plant in Enerhodar city.
Why do you believe that?
I think that if Lesswrong wants to be less wrong, then questions "why do you believe in that?" should not be downvoted.
As for the question itself, I know next to nothing about the situation on this NPP, but just from priors I'd give 70% that if someone shelled it, it was Russian army.
1) It is easier to shoot at NPP if you don't know what you re shooting at. Russian army is much more likely to mistake this target for something else.
2) p(Russian government lies that it wasn't them | it was them) > p(Ukrainian government lies it wasn't them | it was them) (I believe in that since I believe that the left number is very very close to 1.)
3) I am under impression that Russian army uses a lot more artillery. It is somewhat less important for such important target (Ukrainian army is probably incentivized to concentrate their limited resources here), but probably still important.
I'd also like to hear an opinion of somebody who have more information about this.
Because there is a video of the shelling.
Russian media confirms that there was fighting and a fire, though they blame the fire on Ukrainians.
I guess it could be Ukrainians shelling their own NPP, but it seems much more likely that Russian troops did it because they were the ones attacking, so they were more likely to have artillery in place and Ukrainians would have to fire at their own people to shell it.
Power plant shelling
On March 4th Putin's troops shelled Zaporizhzhia nuclear power plant in Enerhodar city. Zaporizhzhia NPP in the largest nuclear plant in Europe, providing 25% of Ukraine's electricity. A training building close to one of the plant’s reactor units caught fire from the shelling. According to Andriy Tuz, the plant's spokesman, firefighters could not initially access the building, because they were shot at. The plant was captured, the fire put out, no radiation was released.
How close did we come to a disaster? Zaporizhzhia power plant has 6 water-water energetic reactors (VVER). This design is used in all Ukraine's active power plants and is a Russian analogue of Pressurized Water Reactor (PWR). Unlike Chernobyl's RBMK reactor, VVER has a concrete containment structure around the reactor to stop any radioactive release. This structure can sustain an aircraft crash. But, according to Najmedin Meskati, a bunker-buster missile would breach it. I'll update once I figure out which kind of missiles Russian troops fired at the plant.
The spent fuel pool is not inside the containment structure, though. If a shell hit it, it could release radiation.
Another source of risk is power shortage. If the power supply to the plant is cut, it can use any of 3 emergency diesel generators to power the cooling systems. The Russian troops may be short of fuel for them, though - more on that below. The plant also has 4 passive emergency cooling systems called "hydroaccumulators": vessels filled with water and pressurized gas. They rely on gas pressure to inject the water and do not need electricity. If all cooling systems fail, the reactor will melt down, like it happened in Fukushima. Spent fuel pools also need constant circulation of water to keep them cool. If they overheat, zirkonium will react with water to produce hydrogen. A hydrogen exlosion caused by this damaged a containment structure in Fukushima.
Human factor adds risk too. Chernobyl was also recently occupied by Russians, and, according to Ukraine, the Chernobyl personnel, "who have been detained by the Russian military without rotation for seven days, are under psychological pressure and morally exhausted and as a result have limited opportunities to communicate, move and carry out full-fledged routine and repair work, which leads to radiation regime disruptions and endangers their lives and health". We may see the same at Zaporizhzhia.
Ukraine has 4 nuclear power plants in total, all with the same VVER design. Ukraine asked NATO to provide a no-fly zone above power plants.
War situation
On February 24th, Putin's troops invaded Ukraine. On February 25th, they asked Ukraine for negotations. Ukraine reports over 9000 dead Russian soldiers, Russia says 498 were killed by March 2nd. I believe Ukraine's report is the correct order of magnitude. This is a lot; in the First Chechen War, around 6000 soldiers were killed in two years. Something did not go according to Putin's plan, but why?
I founded interesting analyses here and here. The author of the second one, Thomas Theiner, has predicted the invasion back in December. The quick summary is that the Russian military based its entire operational plan on the assumption that Ukrainians would welcome Russian forces as liberators and their army would fold without resistance. So they only have one echelon and did not bring maps or GPS navigators, enough fuel or food.
Situation in Russia
The martial law was not introduced in Russia on Friday, but leaving the country is very hard. Western countries closed their airspace to Russian airlines, and Moscow responded in kind. Tickets to planes and trains are either sold out, or cost 10x the normal price. Men get extensively questioned at the border, their luggage and messaging apps searched. Visa and Mastercard will not stop working inside Russia, but people who left the country will lose access to their money.
https://www.theguardian.com/world/2022/mar/03/people-leaving-russia-ukraine-war
Since March 4th, spreading "misinformation" about Russian troops can earn Russians up to 15 years in jail. Calling for sanctions against Russia can cost 3 years in jail. Russian media are blocked for contradicting official Russian sources, or for calling war in Ukraine a war instead of a "special operation".
Thousands of Russians are protesting in the streets. The protests seem to be mostly led by anime-loving young women, e.g:
Russians plan to protest every day at 19.00 on weekdays and 14.00 on weekends at
Moscow - Manezhnaya Ploshchad
Saint Petersburg - Gostiny Dvor
Novosibirsk - Opernyy Teatr Ploshchad
Yekaterinburg - Ploshchad Truda
All cities - Glavnaya Ploshchad
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