Xuewu Cao

The Design of Experiment Equipment for Liquid Lithium Water Interaction

In order to assess the risk of using liquid lithium as plasma facing materials, the experiment equipment for liquid lithium water interaction was introduced in detail. The design temperature of liquid lithium and water were 200 °C to 600 °C and 25 °C to 90 °C, respectively. A furnace was designed to heat solid lithium to molten state in inert gases. The lithium droplets were released into the test section by adjusting the sample release rod made of stainless steel. The shape of lithium droplet and steam generated around the lithium could be observed by the high speed camera. The change of pressure and temperature would be recorded through transducers at the same time. The physical model of liquid lithium water interaction was analyzed, which contained a heat transfer model and a mass transfer model. In addition, an experiment of the solid lithium granule water interaction was performed to debug the devices and make a preliminary assessment of the risk for solid lithium water interaction.Copyright

A Design Proposal and Assessment of In-Vessel Retention Strategy for 2nd Generation PWR

In order to satisfy the higher safety requirements after the Fukushima Accident, in-vessel retention (IVR) strategy is suggested to be a measure for the improvement for the operating 2nd generation Pressurized Water Reactor (PWR). In this paper, a design of passive cavity flooding system isproposed for the 2nd generation modified PWR with reference to the design of in-containment refueling water storage tank (IRWST)for AP1000, and the IVR assessmentis evaluated with the risk oriented accident analysis methodology (ROAAM). Seven representational accident sequences are selected for the IVR assessment and analyzed by lumped-parameter safety analysis computer code. Accident analysis focuses on four key parameters forthe assessment, that is, decay power, zirconium oxidation fraction, and both the mass of oxidic pool and metal layer. The values of them are obtained through analysis and used for the assessment. The probability density distributions of those parameters are determined by combining the analysis results and engineering judgment. The success probability of IVR from the viewpoint of thermal failure is predicted using a program written by the Matlab code. Furthermore, some sensitivity analysis and parametric studies are investigated to support the assessment. The assessment result shows that the success probability of the cavity injection system is higher than 99%. Detail analysis about system reliability and feasibility is needed for further work.Copyright