Session: DA-01-04 Design and Analysis of Pressure Vessels and Components-4

Paper Number: 121989

121989 - Structural Analysis of a Light Water Small Modular Reactor Under Coolant Recirculation Conditions 

  U.S. Nuclear Regulatory Commission proposes a method for evaluating the integrity of a reactor vessel (RV) against pressurized thermal shock (PTS) through the code of federal regulation. With the development of small modular reactors (SMR) in recent years, substantial changes have occurred in the emergency cooling system. In a light water SMR, a passive safety system has been adopted that releases and condenses steam forming a pool outside the RV and recirculates it. Before evaluating PTS, the dominant location of the postulated crack must be selected through an assessment that considers the thermal-hydraulic loads of the external fluid. The objective of this research is to investigate the structural behavior of a RV subjected to supercooling and significant pressure under thermal-hydraulic loads generated by external fluids. A coolant recirculation scenario was assumed by considering the height of the recirculation valve, temperature, and flow rate as variables. Firstly, the transient data of the coolant were derived through systematic computational fluid dynamics simulations for 8 cases. Subsequently, structural analyses were performed to confirm the hoop and axial stress, which are dominant in selecting the crack location. Finally, sensitivity analyses were conducted to quantify the interactions between the parameters and the contribution of each parameter. As results, dominant variables in the coolant recirculation scenario of light water SMR were analyzed. On the RV outer wall, the maximum hoop and axial stress were derived from the cylindrical-truncated cone connection, and the ring-forging weld joint was also evaluated which is vulnerable to PTS. In the case of the RV inner wall, the possibility of PTS occurrence was discussed taking into account the extent of overcooling from the external fluid injected.

Presenting Author: Dong-Hyeon Choi Kyung Hee University

Presenting Author Biography: Kyung Hee University, Korea, Bachelor of Nuclear Engineering.
Student in the Master of 3rd Semester, Department of Nuclear Engineering, Graduate School, Kyung Hee University, Korea.

Authors:

Dong-Hyeon Choi Kyung Hee University
Yoon-Suk Chang Kyung Hee University