Study on CCFL Characteristics in Downcomer during Discharge Phase of LOCA with RELAP5 Code

Li Xiang; Sun Wan; Ding Shuhua; Huang Tao; Li Zhongchun; Pan Liangming

doi:10.13832/j.jnpe.2022.03.0058

Volume 43 Issue 3

Jun. 2022

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Article Navigation > Nuclear Power Engineering > 2022 > 43(3): 58-65

Li Xiang, Sun Wan, Ding Shuhua, Huang Tao, Li Zhongchun, Pan Liangming. Study on CCFL Characteristics in Downcomer during Discharge Phase of LOCA with RELAP5 Code[J]. Nuclear Power Engineering, 2022, 43(3): 58-65. doi: 10.13832/j.jnpe.2022.03.0058

Citation:

Li Xiang, Sun Wan, Ding Shuhua, Huang Tao, Li Zhongchun, Pan Liangming. Study on CCFL Characteristics in Downcomer during Discharge Phase of LOCA with RELAP5 Code[J]. Nuclear Power Engineering, 2022, 43(3): 58-65. doi: 10.13832/j.jnpe.2022.03.0058

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Study on CCFL Characteristics in Downcomer during Discharge Phase of LOCA with RELAP5 Code

doi: 10.13832/j.jnpe.2022.03.0058

1.
Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing, 400044, China
2.
Science and Technology on Reactor System Design Technology Laboratory, Nuclear Power Institute of China, Chengdu, 610213, China

Received Date: 2021-04-21
Accepted Date: 2021-12-07
Rev Recd Date: 2021-09-02
Publish Date: 2022-06-07

Abstract

Abstract

Under the loss-of-coolant accident (LOCA), the two-phase countercurrent in downcomer is extremely likely to cause the vapor-liquid counter-current flow limitation (CCFL), which is not conducive to the smooth entry of emergency coolant into the core, which greatly affects the safety performance of the nuclear reactor system. Based on RELAP5 code, the Wallis overflow relation is used to model the UPFT experimental device and calculate the water injection behavior in the downcomer during discharge phase of LOCA; The validity of the model is verified by comparing the water storage capacity of lower chamber, the pressure in the downcomer and the transient changes of steam flow at the break, and the distribution characteristics of vapor phase velocity field and liquid phase volume fraction in the downcomer are analyzed. The results show that the flow irregularity caused by the three-dimensional characteristics of the channel structure in the downcomer affects the characteristics of the vapor-liquid CCFL. With the increase of steam flow, the greater the pressure gradient and upward flow velocity gradient in the connection area between the break loop and the downcomer, the division method with fewer nodes is difficult to truly reflect the vapor-liquid overflow relationship in the local area of the downcomer channel; The cooling water injected in the circuit close to the break is more difficult to reach the lower chamber, while the cooling water in the circuit far from the break can easily enter the lower chamber; The superheated steam is cooled by the cooling water during the flow process, resulting in condensation, resulting in the steam flow at the outlet being less than the inlet steam flow, and the condensation effect decreases with the increase of the inlet steam flow. The model and method established in this study can be applied to the prediction of vapor-liquid CCFL in the downcomer channel during discharge phase of LOCA.
- Emergency coolant,
- Downcomer,
- Counter-current flow limitation (CCFL),
- Water storage capacity of lower chamber,
- RELAP5

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References(13)

References

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