Original scientific paper
BETHSY 9.1b test calculation with TRACE using 3D vessel component
Andrej Prošek,
orcid.org/0000-0003-0641-3474
; Jožef Stefan Institute Jamova cesta 39, SI-1000 Ljubljana, Slovenia
vidiu-Adrian Berar
; Jožef Stefan Institute Jamova cesta 39, SI-1000 Ljubljana, Slovenia
Abstract
Recently, several advanced multidimensional computational tools for simulating reactor
system behavior during real and hypothetical transient scenarios were developed. One of such
advanced, best-estimate reactor systems codes is TRAC/RELAP Advanced Computational Engine
(TRACE), developed by the U.S. Nuclear Regulatory Commission. The advanced TRACE comes
with a graphical user interface called SNAP (Symbolic Nuclear Analysis Package). It is intended
for pre- and post-processing, running codes, RELAP5 to TRACE input deck conversion, input deck
database generation etc. The TRACE code is still not fully development and it will have all the
capabilities of RELAP5.
The purpose of the present study was therefore to assess the 3D capability of the TRACE on
BETHSY 9.1b test. The TRACE input deck was semi-converted (using SNAP and manual
corrections) from the RELAP5 input deck. The 3D fluid dynamics within reactor vessel was
modeled and compared to 1D fluid dynamics. The TRACE 3D calculation was compared both to
TRACE 1D calculation and RELAP5 calculation. Namely, the geometry used in TRACE is
basically the same, what gives very good basis for the comparison of the codes. The only exception
is 3D reactor vessel model in case of TRACE 3D calculation. The TRACE V5.0 Patch 1 and
RELAP5/MOD3.3 Patch 4 were used for calculations. The BETHSY 9.1b test (International
Standard Problem no. 27 or ISP-27) was 5.08 cm equivalent diameter cold leg break without high
pressure safety injection and with delayed ultimate procedure. BETHSY facility was a 3-loop
replica of a 900 MWe FRAMATOME pressurized water reactor.
In general, all presented code calculations were in good agreement with the BETHSY 9.1b
test. The TRACE 1D calculation results are comparable to RELAP5 calculated results. For some
parameters they are better, this is mostly due to better tuning of the break flow, what influences
timing of the transient. When comparing TRACE 1D and TRACE 3D calculation, the latter is
slightly better. One reason for comparable results is already good agreement of 1D calculations and
there was not much space to further improve the results. The other reason may be that in the facility
the phenomena were mostly one dimensional (for example, external downcomer was used for
reactor vessel modeling). However, when 3D behavior of the heater rod temperatures was
investigated, the advantage of three dimensional treatment was clearly demonstrated.
Keywords
Hrčak ID:
199047
URI
Publication date:
31.7.2017.
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