Nuclear Physicist

Nuclear Physicist is a perk in Fallout 4.

Effects
Increased damage of radiation weapons and lifespan of fusion cores.

Examples
Because radiation poisoning differs from every other damage type in Fallout 4, and the mechanics of how it works may appear to be non-obvious, to help evaluate its usefulness on different weapons, here are some scenarios.

Example 1
Consider a hypothetical Irradiated Pipe Pistol that does 8 base damage and 50 radiation and an enemy with no radiation resistance and 100 health.

Each shot will do 8 damage and poison the enemy with 50 rads, reducing their maximum health by 5. Because 8 is more than 5, you will not notice the radiation damage unless the target attempts to heal, as the damage overlaps - you are effectively dealing 5 unhealable and 3 healable damage per shot.

Example 1 with Healing
Say you shot the enemy 8 times. They have 400 rads (-40 max health) but are at 36 health (64 damage from the base weapon). The enemy runs off and heals; however, due to radiation poisoning, they can only heal to a maximum of 60 health. So even though your initial shots' radiation didn't seem to be relevant for the fight, it is now relevant because it prevented the enemy from healing very much.

Example 2
Consider the same weapon, but now you have enough ranks in Nuclear Physicist to have radiation weapons do double damage. Your Irradiated Pipe Pistol now does 8 base damage and 100 radiation.

Each shot will do 8 damage and poison the enemy with 100 rads, reducing their health by 10. As 10 is more than 8, it is the weapon's base damage that no longer matters - your target is taking 10 unhealable damage per shot.

Affected weapons

 * The Gamma gun is the primary radiation weapon $$
 * Lorenzo's Artifact and the Zeta gun are both unique variants, though neither bestows radiation poisoning like the gamma gun does.
 * Gatling laser
 * Final Judgment is a unique variant of the Gatling laser.
 * Nuka grenade
 * Weapons with the legendary prefix "irradiated".
 * Radium rifle
 * Radical Conversion is a unique variant of the radium rifle.
 * Kiloton radium rifle is another unique variant of the radium rifle, which also benefits from Demolition Expert.
 * Atom's Judgement is a unique variant of the super sledge.
 * Shem Drowne sword is a unique variant of the revolutionary sword. Only the direct radiation damage is affected by the perk.

Perk abilities

 * Because radiation weapons are uncommon (either through the Gamma gun or through a random legendary prefix), it might be best to evaluate this perk mostly for its boost in fusion core efficiency, in addition to its rank 3 ejection ability.
 * Rank 3 states that a fusion core can be used as grenades though in truth they act more like time-based mines. To use this feature, the player has to have no explosives selected in their inventory. To use the ability the player has to use the 'throw explosives/mine ability'. Once used the fusion core will be ejected from behind the player. It will begin to beep and after approximately four seconds it will detonate. It will let off a nuclear explosion similar to a destroyed vehicle or a Mini Nuke with the damage being similar.
 * This ability can be used accidentally easily as you only have to press the button and not hold it down. On a PC using a keyboard, the ability can also be used incidentally when using Alt-tab as Alt is the default key used to activate the ability. When returning to the game and resuming, often there will be a fusion core mine. It is recommended you save prior to minimizing Fallout 4.
 * The ability can be useful when used while fleeing enemies, particularly since the core is ejected behind you.
 * This ability can also be used while using a jet pack upgrade. This can be both an entertaining and effective tactic for dispatching large groups of enemies.
 * The ability has no cool down. As long as you have fusion cores, you can eject a fusion core 2-4 times per second.
 * The explosion size and damage are the same regardless of the charge left in the fusion core. This can be used in your favor to give another use to almost-depleted cores.