VGB POWERTECH 7 (2021) - International Journal for Generation and Storage of Electricity and Heat

Verification of SPACE code based on an MSGTR experiment at the ATLAS-PAFS facility VGB PowerTech 7 l 2021
Fig. 2. Connection nodding diagram of PAFS to ATLAS steam generator.
Connect with steam
supply line
PCHX
Connect with return
water line
Fig. 2. Nodding diagram of PCHX.
the PCCT to evaporate, after which the
steam flowed through the upper pipe on
the top. This upper pipe was connected to
the upper cells of the PCCT. Finally, the
‘TFBC’ component, which was connected
to the upper pipe, played a role in maintaining
the atmospheric pressure. The water
pool of the PCCT served as a heat sink.
The core decay heat was transferred
through the condensation of steam inside
the tubes. Therefore, the extracted heat increased
the temperature of the pool water.
It is expected that rigorous boiling occurred
at the tube outside the surface, and
a strong buoyancy flow was also expected.
In order to simulate natural convection by
buoyancy flow in the PCCT, the 3D option
of SPACE code was applied to model the
PCCT facility as illustrated in F i g u r e 4 .
This PCCT model was divided into 182
cells, where the y direction and the z direction
were respectively divided into 13 and
14 cells. The cooling water was filled up to
nine nodes of the z direction, and the upper
nodes were in atmosphere condition.
The initial cooling water level in PCCT was
about 3.8 m while the water temperature
was 28.8 °C.
3. Results and discussions
3.1 Steady-state results
Before using the SPACE model for transient
analyses, a consistent set of parameters
must be obtained by the steady-state initialization
process. Ta b l e 1 lists the initial
conditions of the experiment, calculated
results of the SPACE code, and difference.
The initial core power generated by
the heater rods was 1.627 MW, and the
heat loss of the primary piping into the atmosphere
was estimated to be about
80