Implementation of the Control Rod Movement Option by means of Control Variables in RELAP5/PARCS v2.7 Coupled Code (NUREG/IA-0402)

Abstract

The objective of this work is to introduce an improvement in best estimate coupled neutronicthermalhydraulic 3D codes simulations, by adding a model for the control rod movement in the coupled code RELAP5/PARCS v2.7, by means of control variables, with the aim of being able to dynamically analyze asymmetric transient accidents, as the reactivity insertion accidents (RIA) in a nuclear reactor, reproducing all the reactors control systems. The modification developed in this work permits the automatic movement of the control rods, activated by the RELAP5 code control system, and also they can depend on signals related to the reactor reactivity, like pressure, fuel temperature or moderator temperature, etc., improving the realism of the calculation and increasing the simulation capabilities. This report was prepared by the Nuclear Engineering Group belonging to the Institute for Industrial, Radiophysical and Environmental Safety (ISIRYM) at the Universitat Politècnica de València (UPV), which collaborates in the simulation area with the Spanish company Centrales Nucleares Almaraz-Trillo (CNAT). The Asociación Española de la Industria Eléctrica (UNESA, Electric Industry Association of Spain), equivalent to the American EPRI sponsored this work.