SMR Nuclear reactor and start-up method of nuclear reactor system

摘要

The present invention relates to an SMR nuclear reactor and a nuclear reactor system starting method. The SMR nuclear reactor according to the present invention includes: a reactor vessel; a core located in the reactor vessel; a steam generator located in the reactor vessel and located on the upper side of the core; a shroud surrounding the core; a riser located on the upper side of the shroud and including a smaller cross section than the shroud; and a heater located between the shroud and the reactor vessel. Accordingly, the present invention can prevent a natural circulation flow from being reduced in the reactor.