Safety aspect of high temperature nuclear reactor application for natural gas steam reforming

An assessment of the safety aspect of high temperature nuclear reactor application for natural gas steam reforming has been carried out. The basic safety aspect associated with nuclear coupling to chemical process is to prevent the release of radioactive materials to the environment and or the chemical process. In utilizing nuclear heat for chemical process, intermediate heat exchanger (IHX) is used as an interface that separates nuclear and non nuclear zones. IHX is helium-helium heat exchanger in which the primary helium (905^oC) coming out from the reactor, and transfer its heat to the secondary helium gas (890^oC). To prevent possible release of radioactive materials from nuclear zone, balanced pressure is applied. The pressure of chemical process (4.5 MPa) is designed to be higher than the pressure of secondary helium (4.1 MPa) or primary helium (4 MPa). The design of balance pressure and the use of IHX cause some inferior condition of the nuclear heated reformer since the lower temperature (~800^oC) reaches catalyst tube of reformer. This condition gives impact on lower thermal efficiency (~50%) compared to the fossil-fuelled plant (80-85%). Some modification in design and operation, such as: selecting the bayonet type of reformer equipped with orifice baffle, and enhancing heat utilization, can improve the lack of condition and are capable to increase the thermal efficiency of nuclear heated natural gas steam reformer to reach about 78%. (author)