High-beta, beam-heated deuterium plasmas in KSTAR will produce a peak neutron yield of 3.5 × 10 per second. Two equally probable D-D fusion reactions occur in a deuterium plasma, one producing 2.45MeV neutrons, and the other producing tritons which are confined in the plasma and undergo D-T reactions producing 14.1MeV neutrons which are about 3 percent of the 2.45MeV neutrons. The biological dose, nuclear heating of the cryogenically cooled magnets, and neutron activation of the surrounding materials have been investigated and their results are used for designing the KSTAR tokamak and the facility. In this work, the Beowulf cluster, Galaxy is used for intensive Monte-Carlo simulations and it is shown to be a cost effective parallel machine.