THERMAL-HYDRAULICS PARAMETER ANALYSIS OF THE BANDUNG TRIGA 2000 REACTOR BASED ON CFD AND RELAP5/MOD3.2

Abstract

Reactor TRIGA 2000 Bandung is result of upgrading TRIGA Mark II reactor from nominal power of 1 MW becomes 2 MW and has been opened its the operation in the year 2000. In this period change of operation parameters had been occurred, especially the parameter related to thermo-hydraulic aspect, like the height of reactor core temperature and the formation of vapor bubble in the core, which is on the contrary with the safety aspect. Safety is the priority in the reactor operation, hence reactor core temperature and vapor bubble in core need to be reduced. One of methods to reduce the core temperature and vapor bubble formation is the operation at limited power of 1000 kW. To examine the safety margin of Bandung TRIGA 2000 reactor operation at 1000 kW power, the analysis of thermo-hydraulic characteristic have been carried out by theoretical study using computer code of CFD (Computational of Fluid Dynamics) and RELAP5/Mod3.2 (Reactor Excursion and Leak Analysis Program). The result of the study indicates that reactor reaches steady state condition at 1000 kW power in 1500 seconds after critical condition, and maximum temperature of reactor core is in C4 position, whereas the maximum temperature of fuel center, cladding, and cooling water at related fuel are 529.35 °C, 103.12 °C, and 90.67 °C, respectively. Maximum temperature of cladding and primary cooling water at related fuel are below saturation temperature (112.4 °C), so the sub-cooled boiling or bubbling of saturation and vapor bubble formation can be predicted not to be happened. Besides when the reactor was operated at 1200 kW and 1250 kW power was obtained the maximum temperature of fuel cladding are 111.04 °C and 115.53 °C, respectively. This thing informs that, when the reactor was operated up to 1200 kW power sub-cooled boiling has not happened, but when the reactor was operated at 1250 kW power has started the happening of the sub-cooled boiling and the formation of vapour bubble. The result of this study can be used as a valuable information in operating Bandung TRIGA 2000 reactor at the limited power of 1000 kW and revising safety analysis report (SAR) of Bandung TRIGA 2000 reactor.