Nuclear Techniques ›› 2020, Vol. 43 ›› Issue (9): 90606-090606.doi: 10.11889/j.0253-3219.2020.hjs.43.090606


The effect of scram rod drop time on the consequences of molten salt reactor reactivity insertion transient

Kai WANG,Xiaowei JIAO,Qun YANG(),Yanhua WANG Chaoqun WU,Zhaozhong HE   

  1. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
  • Received:2020-02-13 Revised:2020-05-04 Online:2020-09-15 Published:2020-09-09
  • Contact: Qun YANG
  • About author:WANG Kai, male, born in 1987, graduated from North China Electric Power University with a master's degree in 2012, focusing on reactor safety
  • Supported by:
    the Project of Youth Innovation Promotion Association of Chinese Academy of Sciences(Y929022031)

Abstract: Background

The scram rod drop time is an important parameter for reactor safety analysis, which is of great significance to the safety of molten salt reactor (MSR). The process and the consequences of the design basis events of the MSR will be significantly influenced by the dropping time of scram rod.


This study aims to analyse the effect of the scram rod drop time on the consequences of MSR reactivity insertion transient.


First of all, the RELAP-MS based RELAP5-TMSR (reactor excursion and leak analysis program-thorium molten salt reactor) code was employed to establish the safety analysis model for the transient simulation of TMSR-LF. Then, the sensitivity of control rod withdrawal speed to transient consequences was analyzed, next, reactivity introduction event caused by the withdrawal of a control rod at full power was taken into account to analyse the vartions of power, temperatures of fuel salt and structure materials. Influence of scram rod dropping time in emergency shutdown on transient consequences of reactivity introduction in MSR was analyzed.


Even if the scram rod drop time reaches as long as 10 min, the maximum temperature of Harrington alloy is 708.2 °C, and the maximum temperature of fuel salt is 709.2 °C, which is below the safety limit.


The molten salt reactor has good safety characteristics, low requirements for scram rod drop time, and the ability to deal with reactivity insertion event.

Key words: Molten salt reactor, Scram rod drop time, RELAP-TMSR, Safety analysis

CLC Number: 

  • TL36