Profiling and analysis of control rod speed design on core power control for TRIGA reactor

Abstract

In nuclear reactor TRIGA PUSPATI (RTP) operation, conventional Control Rod Speed Design (cCRSD) uses hard saturation to control rod insertion step as a function of the reactivity insertion rate in the reactor core to ensure the power output will not exceed the limit for the operational safety. The cCRSD which is part of the core power control system produces relatively long settling time during transient and a chattering noise signal during steady-state. Therefore, the current study proposed a new CRSD based on different saturation types such as soft and sigmoid function saturation and changes in the maximum control rod speed limiter value. In this paper, the new CRSD (nCRSD) is designed, profiled, and analyzed based on simulation of an actual Control Rod Drive Mechanism (CRDM) model, common types of saturation models, and reactivity rod worth curve experimental data to predict the best reactivity insertion rate response for operations. The model for core power control is based on mathematical models of the reactor core, the FCA controller, and the CRSD model. The mathematical models of the reactor core are based on a point kinetics model, thermal-hydraulic models, and reactivity models. The nCRSD model is integrated with the Proportional-Integral (PI) type controller and the model of the reactor core. The performance of the nCRSD and cCRSD is compared via computer simulation and experiments. Overall, the results show that the response from the nCRSD offers better results than the cCRSD, which reduces the rise time by up to 52%, the settling time by up to 26%, and the chattering error by up to 25% of the nominal value.