Steps to reproduce

1. Grab a full stack of Californium-252
2. Die from radiation poisoning
3. Respawn
4. Die from radiation poisoning
5. Go back to step 4

My friend died nearly 60 times from this before I was able to give him enough Rad-Away between spawns to prevent him from dying.

I'm playing All The Mod Remix 3 - 1.6.0 which uses NuclearCraft-2.18u-1.12.2.

It sounds like you're not playing with default configs which give players a ninety second window of immunity after respawning to be able to regroup. If you do have that enabled and are still having trouble, I recommend increasing the decay rate of chunk and/or player radiation :)

It says here that you are playing with a sixty second immunity window (not the default, but still a decent amount of time):
# Number of seconds players will have radiation immunity after death due to radiation.
D:radiation_death_immunity_time=60.0

When you die, do you not have this immunity?

It sounds like you're not playing with default configs which give players a ninety second window of immunity after respawning to be able to regroup. If you do have that enabled and are still having trouble, I recommend increasing the decay rate of chunk and/or player radiation :)

I believe I am playing with the default config, as I have not changed the ATMR 3 configs from their default and I believe they use the default. If not, can you tell me how I can change my config? Here is my config.

You start taking damage immediately after respawn, and typically die within 15 seconds of spawn. When I go into creative and check my radiation level with a geigercounter, it shows the radiation bar as full.

It is worth noting this death loop only seems to happen if you pick up enough radioactive material to cause an instant death. Hence, a full stack of Californium-252 does the trick. If I pick up enough material that it causes a slow death, and then die from that slow death. My radiation levels are much lower when I respawn.

The place I respawn is very close to 0 Rads/t as my nuclear reactor is far away from my spawn point.

It is also worth noting, that one of my friends died at least 30 times (from counting his gravestones) after accidentally grabbing a full stack of Californium-252 before I could give him the rad-away he needed. Which since his radiation levels are suppose to half every time after death, his radiation levels would have had to been at least a billion time more than a lethal dose, which seems highly unlikely.

Based on my loose understanding of how the NuclearCraft code works, I would assume there is some integer overflow issue going on, but I didn't see anything in the logs.

I guess if other people have this problem, my solution to this, as I've accidentally done it enough that I needed a solution to this. Was to have a beacon with health regeneration and a chest full of radaway near my bed.

@salomj Did you send me your client configs or server configs? If it was the former, it may be that the immunity is not enabled on your server.

I actually keep the server config synced to my github project, you can see here. https://github.com/TeamJoe/MinecraftStuff/blob/master/pdx-004/home/minecraft/data/ATM3/config/nuclearcraft.cfg

Hmm, configs look fine, albeit not exactly the defaults. When you or your friend dies, it does say died due to fatal radiation poisoning, right? I've just recreated this in my test world and the immunity works fine...

Looks like the first was was died due to fatal radiation poisoning and the rest are withered away

The affects my character has are Mining Fatigue III, Hunger II, Weakness III, Poison, and Wither on respawn. And these affects don't go away until I take Radaway. So I appear to have this affects due to the radiation, I officially die from Wither which is caused by the radiation, but since I don't explicitly die from fatal radiation poisoning my radiation levels don't go down and I get stuck in an endless cycle of dying.

Ah, I see what's happening - my bad. You have radiation_death_persist set to false, so you aren't retaining any of the radiation on respawning, but it must be that the area around the death point is so high that it's immediately killing you again. For some reason I had it so that immunity is only given when radiation death persistence is true... I've just put a fix up on CF, thanks for your patience :)