SHIELDING DESIGN TO OBTAIN COMPACT MARINE REACTOR

The marine reactors equipped in previously constructed nuclear ships a re in need of the secondary shield which is installed outside the cont ainment vessel. Most of the weight and volume of the reactor plants ar e occupied by this secondary shield. An advanced marine reactor called MRX (Marine Reactor X) has been designed to obtain a more compact and lightweight marine reactor with enhanced safety. The MRX is a new typ e of marine reactor which is an integral PWR (The steam generator is i nstalled in the pressure vessel.) with adopting a water-filled contain ment vessel and a new shielding design method of no installation of th e secondary shield. As a result, MRX is considerably lighter in weight and more compact in size as compared with the reactors equipped in pr eviously constructed nuclear ships. For instance, the plant weight and volume of the containment vessel of MRX are about 50% and 70% of thos e of the Nuclear Ship MUTSU. in spite of the power of MRX is 2.8 times as large as the MUTSU's reactor. The shielding design calculation was made using the ANISN, DOT3.5, QAD-CGGP2 and ORIGEN codes. The computa tional accuracy was confirmed by experimental analyses.