Study on self-initialization algorithm of SCDAP/RELAP5 code

Full text of publication follows. The SCDAP/RELAP5 (SR5) code, which is composed of the RELAP5 code and the SCDAP model, is a severe accident analysis code for nuclear power plants. In order to simulate a consistent accident scenario with SR5, a correct initial steady-state condition must be generated. RELAP5 provides useful controller components for the self-initialization purpose. However, many users still use the trial-and-error approach to generate the initial conditions. This paper demonstrates the application of the self-initialization algorithm of the RELAP5 and SR5 codes. Kuosheng nuclear power plant (NPP), a GE BWR-6 with MARK III containment, and Maanshan NPP, a Westinghouse pressurized water reactor plant, are cited as a reference plants. First, the standard controller components provided in the RELAP5 model are described. Then, a set of controllers that mimic an actual plant control system is applied to establish the steady-state conditions for Kuosheng and Maanshan NPPs with the SR5 code. The problems associated with the self-initialization are discussed and solved. The initialization work of partial-power conditions of the Maanshan NPP is also demonstrated. These initial conditions are successfully generated with the RELAP5 controller components. By using this feature, it not only improves the accuracy of the simulation, but also eliminates the tedious trial-and-error initialization process. (author)