I spent most of tonight preparing for nuclear and just got on with my buddy to finally connect it all and try it out. We watched the temperature rise and rise, and when it hit 500... it didn't stop. It went to 502.98°C and desync'd us both. https://i.imgur.com/HTk8zRN.jpg
We reconnected and kept watching, it disconnected us again around 560°C, then steadily rose all the way to 999.97°C and stayed there. https://i.imgur.com/bRaqj19.jpg
The heat exchangers are at 999.88-999.90°C and their water temperature is at 15, which strikes me as odd, and the steam turbines work at 500.00°C as expected.
The server has been stable since then. I'm not sure what else to provide, especially since I'm client and not host, but just in case that somehow helps, here's our power consumption window? https://i.imgur.com/jOmwOK0.jpg
[0.15.5] Starting nuclear reactor in multiplayer issues
Re: [0.15.5] Starting nuclear reactor in multiplayer issues
Should be fixed if you update the game 

If you want to get ahold of me I'm almost always on Discord.