All antischrabidium explosions deal around 3 damage.

Version: NTM extended 2.0.2
Mod list:
NTM-Extended-1.12.2-2.0.2
jei_1.12.2_4.16.1.301
NotEnoughItems_1.12.2_2.4.3.245_universal
CodeChickenLib_1.12.2_3.2.3.358_universal

Some of affected weapons \ items:

Tossable Antischrabidium cell (more dmg with direct hit)
Antischrabidium cell (more dmg but still around 10-20 dmg)
b92
b93 energy mod (3-4 charges)
Schrabidium missile

I think maybe all weapons \items that using this type of explosion affected, sometimes they literally can't kill a chicken.

Some of the small nuclear explosions also have around 0-10 damage:

40 mm grenade (Привет)
84 mm rocket (Привет)
Sometimes you literally can shot under your legs and take 0 damage from explosion.

Around ~5-15 dmg:

Nuka Grenade
Micro-Nuclear Missile

M42 Nuclear Catapult 'Fat Man' ammo type: Tiny tots
M42 Nuclear Catapult 'Fat Man' ammo type: Mini Nuke (safe) - deals dmg only with direct hit
M42 Nuclear Catapult 'Fat Man' ammo type: Mini Nuke (Low Yield)

Almost the same results for M42 Nuclear Catapult 'Experimental MIRV'

P.s.: I didn't test all weapons with nukes \ balefires

Are you wearing any armor or sth reduces damage?

Are you wearing any armor or sth reduces damage?

No.
No armor. No resistance effects, nothing.