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Scaling analysis for PWR steam generator

 LI Yuquan1, and YE Zishen2
 
1.State Nuclear Power Technology R&D Center, Beijing, 100190, China (yuquan.li@gmail.com)
2. INET, Tsinghua University, Beijing, 100084, China (yezs@tsinghua.edu.cn)
 
Abstract: To test the performance of a nuclear power plant safety system and to verify the relevant safety analysis code, a widely used approach is to design and construct a scaled model based on a scaling methodology. For a pressurized water reactor (PWR), the SG scaling analysis is important before designing a scaled model, which is expected to simulate well the system response of the prototype system in an accident. This work first presents a review of the transient process in SG during a loss of coolant accident (LOCA), and then describes a brief scaling analysis for a natural circulation to get the basic scaling criteria for the SG. The U-tube scaling design showed that if the diameter ratio was different from the length ratio for a model, the thermal height center would be enlarged because the length of the U-tube should be scaled by the length ratio. Therefore the improperly scaled buoyant force would cause a distortion in natural circulation simulation. By single phase heat transfer scaling analysis, a relation between the U-tube diameter ratio and the height ratio was obtained. It showed that the diameter ratio decreased with the decrease of the height ratio. Finally, the transition of the role played by the SG, from heat sink to heat source, was analyzed. The results showed that the inventory of the secondary side of the SG and the total metal heat capacity should be properly scaled in order to represent the transition correctly.
Keyword: scaling analysis; U-tube; integral test facility; decay heat removal; steam generator
 
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