Session: MF-05-01 Fitness-For-Service and Failure Assessment-1

Paper Number: 121895

121895 - Fitness-for-Service Analysis of Reactor Components Under Complex Operating Conditions 

Conventional power plants, including nuclear facilities, have been traditionally engineered to provide a steady baseload capacity, optimizing output efficiency to minimize variable costs. However, the growing adoption of large-scale renewable energy-generation systems, which rely on intermittent sources such as solar and wind, has introduced more variability into the energy supply for the interconnected electricity grid. As a result, new generation of conventional power plants need to operate in what is known as the load-following mode, requiring flexible adjustments in production to align with the energy demand on the grid. This transition to load-following operating conditions can lead to significant thermo-mechanical cycling, speeding up material degradation, thereby elevating the risk of potential failure. It becomes imperative to conduct a comprehensive analysis of fatigue, creep-fatigue, and stress corrosion cracking life, to assess the resilience of the various engineering components under these demanding operating conditions.

This study aims to develop a comprehensive numerical model of a light-water reactor pressure vessel (RPV) to investigate its degradation under various operating scenarios. Utilizing a coupled thermo-mechanical finite element modelling approach, the stress response of the RPV is evaluated, considering fluctuations in thermal and mechanical loads caused by the varying pressure and temperature occurring during the load-following service conditions. Critical locations on the RPV are subsequently identified based on the stress response. The stress intensity factors for the postulated flaws at those locations are then calculated, followed by an evaluation of the reactor’s life in accordance with the ASME Boiler and Pressure Vessel Code Section XI. This comprehensive life assessment covers varying operating conditions, providing invaluable insights into the RPV’s structural integrity. Moreover, the development methodology can be adapted to other reactor components, as well as components of conventional power stations that are affected by fluctuating operating conditions, leading to fatigue, creep-fatigue, and stress corrosion cracking.

Presenting Author: Benjamin Spencer Idaho National Laboratory

Presenting Author Biography: Dr. Benjamin Spencer is a computational scientist in the Fuel Modeling and Simulation Department at Idaho National Laboratory. He currently serves as the lead of the Structural Materials & Chemistry Technical Area in the US Department of Energy’s Nuclear Energy Advanced Modeling and Simulation (NEAMS) Program. His background is in computational solid mechanics, and he is actively involved in the development of simulation codes based on the open-source MOOSE framework. He has performed extensive research in areas including nuclear fuel performance modeling, computational methods for solid mechanics and multiphysics simulation, fracture mechanics, and degradation of structural components in nuclear power plants.

Authors:

Minh Tran Australian Nuclear Science and Technology Organisation
Ondrej Muransky Australian Nuclear Science and Technology Organisation
Benjamin Spencer Idaho National Laboratory