So, I finally got into my main world to try the new update and it seems that you're messing with health in a way that it removes all bonus health gained by other mods, and I cant seem to get it back. My android powers are trying to regain the lost health and I keep getting the "Damaged" screen shake every so often.

Ah well. Going to have to revert.

I seem to found the reason for my health-bar problem. I also experienced that my maximum hearts are reduced after I used the creative gamemode for a second.

Anyway I updated to NuclearCraft-1.9d and it happened. After an "update" or exchange was showed me on Curse, I updated the the "NuclearCraft-1.9d" to NuclearCraft-1.9d files, because I presumed a bugfix...

Sadly with this update I wasn't able to load my world anymore because a (probably config related) crash. I noticed later the change in FILE-CHANGELOGS and the arrangement of the file, so I downgraded back to Recommend NuclearCraft-1.9c again.
But unfortunately this didn't fixed it the health problem.

2 Hearts (4 half-hearts) were gone. I had to fix it with the NBT-Explorer (set (level.dat/Data/Player/HealF) from 16 to 20 again.).

I hope this helps a bit.

Well, what you experienced was having a ton of radiation. as far as I know. Or just maybe my mods counteract it. Anyway, I didnt have to do anything special other than downgrade and get all my hearts back. (like 89 hearts, tinker's and a heart mod)

Hopefully this helps - here's a stable build without the radiation mechanics: https://minecraft.curseforge.com/projects/nuclearcraft-mod/files/2330045
This is certainly recommended for those who simply want to update the mod for their long-term worlds, but remember to turn off all Fission Reactors before updating!