Nuclear Techniques ›› 2019, Vol. 42 ›› Issue (12): 120601-120601.doi: 10.11889/j.0253-3219.2019.hjs.42.120601

• NUCLEAR ENERGY SCIENCE AND ENGINEERING • Previous Articles     Next Articles

Simulation experiment study on release of fission gas at fuel cladding failure

Leihao DONG Bing LI Chenyue YIN Junlian WANG Dezhong LI   

  1. Shanghai Jiao Tong University, Shanghai 201100, China
  • Received:2019-07-20 Revised:2019-10-11 Online:2019-12-10 Published:2019-12-18
  • Supported by:
    National Natural Science Foundation of China(11675105)

Abstract: Background

When fuel rod cladding failure occurs, the defect needs to be determined and information needs to be provided for system response in time. Escape rate of fission gas is adopted to reflect the defect size. However, there is hardly researches on mechanisms of gas release.

Purpose

This paper studies the effect of unsteady process, the pressure and temperature of the coolant on the instantaneous escape rate of the rod cladding breach by experimental simulation.

Methods

First of all, the experimental apparatus was designed on the base of geometric similarity, flow similarity and flashing similarity. Then, influence of coolant pressure and temperature in a subchannel was investigated by using computational fluid dynamics (CFD) methods. Effect of flashing on unsteady process and escape rate in short-term were analysed.

Results

The results indicate that unsteady process has no distinct effect on release of gas at defect size of 0.5 mm. Long-term escape rate remains steady during experiments and release process can be described by first-order kinetics. At the same coolant pressure, long-term escape rate increases when coolant temperature changes from 90 ℃ to 110 ℃. At the same coolant temperature, long-term escape rate decreases when coolant pressure changes from 0.3 MPa to 0.5 MPa.

Conclusions

A negative correlation is found between long-term escape rate and subcooled temperature, which indicates that liquid layer formed on the defect has impact on fission gas release.

Key words: Fuel cladding failure, Unsteady process, Escape rate

CLC Number: 

  • TL99