The Modeling of Subheated Coolant Influence on Temperature Measurement at the Exit of Fuel Rod Assambly in WWER-1000 reactor
Errors in measurement of bulk temperature at the core exit of WWER-1000 reactor depends on the flow of relatively cold coolant through the control rod guide thimble tube in the fuel assembles – so called “absorber” effect. The problem of temperature field modeling at the exit from WWER-1000 reactor corewas solved in order to predict influence of such effect on thermocouple registrations along reactor radius at reactor measurements. The problem was solved in two stages. Energy release within the core elements of serial WWER-1000 reactor was calculated using the neutron transport code MCNP. The temperature field was calculated by using the OpenFOAM CFD package and heat release distribution, obtained at first stage of calculations. The results, obtained with developed methodology, are in good agreement with the reactor measurements results and researches of other authors. Obtained data allowed evaluating influence of the “absorber” effect at measurements in different position along core radius of WWER-1000 reactor.