Validation of TRACE Code for Type-I Density Wave Oscillations in SIRIUS-N Facility, which Simulates ESBWR
NURETH-14 - 2011 September 25-30

Presented at:
2011 September 25-30
Toronto, Canada
Session Title:
B13-1 Development, Assessment and Applications of TRACE

Masahiro Furuya (CRIEPI)
Yoshihisa Nishi (CRIEPI)
Nobuyuki Ueda (CRIEPI)


As a part of the international CAMP Program of the US Nuclear Regulatory Commission (US- NRC), the best-estimate code TRACE is validated with the stability database of SIRIUS-N facility at high pressure. The TRACE code analyzed is version 5 patch level 2. The SIRIUS-N facility simulates thermal-hydraulics of the economic simplified BWR (ESBWR). The oscilla- tion period correlates well with bubble transit time through the chimney region regardless of the system pressure, inlet subcooling and heat flux. Numerical results exhibits type-I density wave oscillation characteristics, since throttling at the core inlet shifts stability boundary toward the higher inlet subcooling, and throttling at the chimney exit enlarges unstable region and oscilla- tion amplitude. Stability maps in reference to the inlet subcooling and heat flux obtained from the TRACE code agrees with those of the experimental data at 1 MPa. As the pressure increases from 2 MPa to 7.2 MPa, numerical results become much stable than the experimental results. This is because that TRACE underestimates two-phase frictional loss at such high pressure, since the natural circulation flow rate of numerical results is higher by up to 17 % than that of experimental results.

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