Abstract
Air pollution and the energy problem have become concerned and urgently needed to be solved all over the world in recent years. Coal-fired boilers in industrial parks are an important source of air pollutants. Low temperature heating reactor built in industrial zone is an ideal substitute for coal-fired boiler because of its excellent inherent safety and cleanliness. The new type nuclear heating reactor named NHR200-II was proposed by Institute of Nuclear and New Energy Technology of Tsinghua University in 2015[1]. Compared with the previous generation NHR200, the thermal parameters of NHR200-II are improved which can not only be used for regional heating but also realize the multi-purpose like power supply, steam supply and seawater desalination. And the economic benefits are also greatly improved. The design of NHR200-II is based on the design, construction and operation experience of NHR5 which has maintained running safely up to now and NHR200. The main technical features include three circuit design, integrated layout of primary circuit, full power natural circulation, and automatic self-pressurization.
NHR200-II uses the traditional anti-seismic technology at present. However, the requirements of seismic performance of reactors have generally increased after Fukushima disaster. This paper tries to apply seismic isolation in NHR200-II to meet the improved requirements of seismic performance and realize the standardized design by which the magnitude of design ground motion is not restricted in the future. Base isolation, which means setting isolation devices like elastomeric bearings or spherical sliding bearings between the foundation and the superstructure, has been widely applied in normal buildings and bridges, but still needs particular design for nuclear reactors.
This paper describes NHR200-II seismic isolation system, which consists of the foundation, raft, isolation layer and the whole nuclear island as superstructure. In addition, the paper also tells the design process of the system, including designing of the raft, selecting of isolators and their layout design based on the environment and mechanical property, etc. And the particular calculation method of the performance parameters and acceptance criteria are also shown in this paper. Finally, the overall design method of seismic isolation is given as a conclusion.
