Reactivity disturbance suppression method for small modular reactors based on core coolant flow control

Area of Science:

• Nuclear Engineering
• Reactor Physics
• Thermal-Hydraulics

Background:

• Small modular reactors (SMRs) offer flexibility but exhibit higher reactivity susceptibility compared to large commercial reactors.
• Limited space in SMRs restricts the use of control rods for effective reactivity compensation.
• Deviations in core power can occur due to reactivity disturbances, impacting operational stability.

Purpose of the Study:

• To propose a novel method for improving the operational stability of SMRs.
• To address the limitations of control rods in compensating for reactivity disturbances within SMRs.
• To enhance the reliability and safety of SMR operation through indirect reactivity control.

Main Methods:

• Indirectly adjusting nuclear fuel temperature by manipulating coolant flow rate.
• Utilizing the Doppler effect of nuclear fuel resonance absorption to compensate for reactivity disturbances.
• Conducting simulation experiments to validate the proposed method's effectiveness.

Main Results:

• The proposed method effectively compensates for reactivity disturbances that are challenging for control rods alone.
• Simulation results demonstrate the capability to eliminate reactive disturbances under SMR-specific constraints.
• The technique enhances SMR operational stability, particularly in space- and control-rod-limited scenarios.

Conclusions:

• Adjusting coolant flow rate is a viable strategy for indirect reactivity control in SMRs.
• This method provides a practical solution for improving SMR operational stability.
• The findings contribute to the advancement of SMR technology and safety.