>>537628856
Only reactors running at full capacity give 100% neighbor bonus.
In the case if 2 reactors, if the plasma outputs are separate, load is distributed equally across all the generators and thus the reactors. The reactors operating at A capacity means (1+A) times energy from fuel, resulting in 2 * A * (1 + A) * 100MW energy production. If you draw 200 MW, then you get 2 * A * (1 + A) = 2, so A is the golden ratio, about 0.618.
If the plasma is connected, then the closest reactor operates at 100% plasma, but the furthest reactor does not. If the further reactor operates at A capacity, the total energy generated is (1+A) * 100MW + 2 * A * 100 MW. If you draw 200 MW, then you get 1 + 3 A = 2, so A is about .333.
Either case, you aren't getting full neighbor bonuses on the reactors.