TYPICAL TECHNOLOGY OF MECHANICS ON GEN-Ⅲ PASSIVE NPPS AND GEN-Ⅳ ADVANCED SUPERCRITICAL LIGHT WATER REACTORS

摘要

Technical requirements for Gen-Ⅲ advanced nuclear power plants, which take passive reactors as the main body, were originally brought forward in American "Advanced Light Water Reactor Utility Requirement Document" (ALWR-URD) in early 1990's. The primary characteristic of passive nuclear power plant is large amount of simplification to the original active safety systems, replacing or supplementing them with passive safety systems, which enhances safety and economy. However, the replacement of active safety systems by passive safety systems also brings about some mechanics that compel attention, typically, such as load-carrying capability evaluation for steel containment, in-vessel retention (IVR) of molten core debris, seismic design without OBE, thermo-hydraulic issues concerning with coupling between two-phase fluid and solid, etc. At the beginning of this century, six typical Gen-Ⅳ advanced reactor types (Sodium Cooled Fast Reactor, Supercritical Water-Cooled Reactor, etc.) were put forward. Among these types of reactors, Supercritical Water-Cooled Reactor adopts supercritical water as coolant and operates above the thermodynamic critical point of water by increasing temperature and pressure of the coolant, which makes the plant economic and efficient. However, this type of reactor also brings about some mechanical difficulties (e. g. pressure fluctuation caused by the supercritical fluid in the core, creep of materials working at high temperature, etc.) for the design of facility and components. In this paper, the issues mentioned above are outlined for further consideration.