Simulation of GR19 sodium boiling experiments with cathare 2 system code and Trio_U MC subchannel code
Abstract
The CEA R&D program on SFRs includes the study of reactor behavior during accidental transients
possibly leading to sodium boiling, such as an unprotected loss of flow. To that end, two existing CEA
thermal hydraulic codes are being extended to model two-phase sodium flows: CATHARE (system
dynamics) and Trio_U MC (subchannel). In the case of the 6-equations CATHARE code, the
applicability of its current closure laws to two-phase sodium flow must be evaluated; for the 3-equations
MC code, new numerical methods are needed as well.
This paper reports simulations with these codes of the GR19 sodium boiling experiments done at CEA
Grenoble in the 80’s. Simulations of boiling test on this 19-pin out-of-pile mock-up were undertaken in
order to provide a preliminary validation of the two codes and to guide future code improvements.
The results presented here show that CATHARE can achieve good agreement with the experimental data:
however, some closure laws (especially for heat transfer) will still have to be revised to better fit sodium
boiling physics. Meanwhile, Trio_U MC is capable of predicting correctly the occurrence and extension
of local boiling in boiling steady states: however, further improvements will be needed to correctly model
unstable and transient boiling.
Origin : Files produced by the author(s)
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