Incorrect. Energy forms that don't obey the inverse square law are BY DEFINITION directed energy, beams that exhibit coherence and have different attenuation properties. Delta rays, therefore, would definitely obey the inverse square law unless they were emerging from the reactor vessel as a pencil-thin beam with laser-like coherence. And if your radiation emissions are that tightly concentrated, shielding them--or even capturing them for energy conversion--should be a pretty simple matter. The only time you get a problem with radiation in that case is if something interrupts the beam and scatters it, in which case you have a radiation shine with standard inverse-square relationships. And this is before you take into account secondary reactions and inefficiencies which means SOME radiation will always be leaking out beyond your ability to contain it. In that sense, having the reactor positioned 50 meters away from the hull and on the other side of your external radiation shielding (which is designed to deflect cosmic radiation and and weapons fire anyway) solves this problem nicely. Actually, the diesel engine doesn't scorch you because it CONTAINS more of that energy to a smaller area while the searchlight intentionally radiates more of it. The only reason it's producing less waste heat is because more of its output energy is in the form of mechanical torque, and yet it will still burn you if you're sitting directly on top of the engine while it's running. We're talking about a matter-antimatter reactoin chamber (warp core) that produces power outputs in the thousands of gigawatts. Even if that reactor is 99% efficient (a thermodynamic impossibility), that means it's producing many hundreds of gigawatts of waste heat that has to be rejected by SOMETHING. That means you're going to have to have one hell of an advanced cooling system for it, because anything that isn't dissipated into the cooling system is going straight into the surrounding environment. Even if the reaction chamber itself manages to absorb 99% of that waste heat, the 1% that gets through adds up to around 100MW of heat. That's the equivalent of building a huge bonfire in the middle of your engine room burning five liters of kerosine per second. This isn't an engine room, it's a pizza oven.