COMPUTATIONAL FLUID DYNAMICS SIMULATION OF THE ATUCHA II NUCLEAR POWER PLANT REACTOR

RAMAJO DAMIAN; SANTIAGO CORZO; SANTIAGO MÁRQUEZ DAMIÁN; NORBERTO NIGRO

Rosario

Congreso; Encuentro Nacional de Investigadores de Elementos Finitos; 2011

Asociación Argentina de Mecánica Computacional

A Computational Fluid Dynamics (CFD) simulation of the Heavy Water Pressure Reactor(PHWR) of the Atucha II nuclear power plant was developed. A 3-dimensional (3D) detailed modelwas employed to simulate the upper and lower plenums, the down comer and the hot-legs and cold-legs. The control rods and the coolant channel walls were also included to account for their influenceon flow mixing. The behavior of the coolant channels was modeled by imposing the nominal massflow at mass and momentum sinks and sources at the location of the inlet and outlet coolant channelports, respectively. The hydraulic zone distribution was also considered, applying different mass flowrates according to the local coolant channel location. In this preliminary work, the nominal mass flowrate was imposed to the channels to know the steady state reactor behavior. Latterly the mass flow ratethrough each one of the coolant channels was calculated based on the local pressure at the channelends at the lower and upper plenums. Simulations allowed a deep understanding of the complexthermo-hydraulic phenomena inside the reactor plenums. The temperature profile and the velocityfield inside the upper plenum could be visualized. This computational model is the first step fordeveloping a real time dynamic model, which will be capable to simulate unsteady conditions andsome typical operational problems like control rod stepping caused by thermal stratification in the hot-legs or hot-leg streaming.