The Tokamak is a prototype fusion reactor in the experimental stages housed in the Ashland Generating Facility. It is funded by the local University and the project is led by department head Dr. Nicholas Turner and a student named Dean. The intent was to move away from fossil fuels to more clean fusion energy.
Tokamak works on the principle of the sun. Hydrogen and deuterium is released into the reactor and heated to 10-million degrees, then the elements fuse together, releasing a tremendous amount of energy. The rector is outfitted by magnets which will keep the super-hot plasma contained. However, Nicholas Turner decided to shut down the project and cut any further funding for it.
While fighting the aliens, Dean, Hastings and Wasach lure them to the Ashland Generating Facility to destroy their eggs. Dean activates the Tokamak reactor and climbs inside with a remote. While thinking he doesn't make it, he deactivated the magnets, which would lead to an explosion that would have destroyed the whole facility. Dean managed to close the safety shaft before the rector exploded.