Development of a high order boron transport scheme in TRAC-BF1.

Autores UPV
CONGRESO Development of a high order boron transport scheme in TRAC-BF1.


In pressurized water reactors (PWR) the reactivity control is accomplished through movement of the control rods and boron dilution, meanwhile in boiling water reactors (BWR) the importance of boron transport lies in maintaining the core integrity during ATWS-kind severe accidents in which under certain circumstances a boron injection is required. This is the reason for implementing boron transport models thermal-hydraulic codes in NRC codes as TRAC-BF1, RELAP5 and TRACE. The boron transport models implemented in NRC codes are based on a calculation according to a first order accurate upwind difference scheme. There is a needing of reviewing and improving this model. Four numerical schemes that solve the boron transport model have been analyzed and compared with the analytical solution that provides the Burgers equation. The studied numerical schemes are: first order Upwind, second order Godunov, second-order modified Godunov adding physical diffusion term and a third-order QUICKEST using the ULTIMATE universal limiter (UL). The modified Godunov scheme has been implemented in TRAC-BF1 source code. The results using these new schemes are presented in this paper.