These are 80's era Soviet VVER PWRs. They are better designs than Chernobyl style RBMKs, but they're not at par with Western PWRs. In particular they lack much of the automation expected in Western designs.

The danger here is if these were still operating at power when the Russians rolled in and residual heat is not removed because operators have fled or the power gets cut then the core(s) will melt. Melting cores generate hydrogen gas which then explodes. Also, there is probably a large quantity of spent fuel on site, some of which needs active cooling as well.

The account seems credible enough, but there's something weird about citing a military intel account named and themed on a meme.

It's just one of many OSINT accounts on Twitter that report / summarize what's coming through via both Telegram users and official sources.