IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research
IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research
IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research
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IGC<br />
<strong>Annual</strong> <strong>Report</strong> 2007<br />
operational problems of the<br />
reactor.<br />
Hence, it is important to<br />
mitigate the gas entrainment at<br />
the free surface of the hot pool.<br />
Making free surface quiescent<br />
is one of the means to mitigate<br />
gas entrainment from free<br />
surface. The numerical and<br />
experimental studies carried out<br />
in a large scale model showed<br />
that inclusion of ring type baffle<br />
plate below the free surface<br />
was very effective to reduce the<br />
free surface velocity. With the<br />
employment of such simple<br />
baffle plate the free surface<br />
velocity was reduced to half of<br />
its original value. No surface<br />
vortices were also seen at the<br />
free surface. However, it was<br />
found from the experiment that<br />
approximately a margin of 100<br />
mm on the nominal free level<br />
height is available in PFBR at<br />
nominal flow rate be<strong>for</strong>e the<br />
onset of vortex activated gas<br />
entrainment from free surface.<br />
With the objective to improve<br />
this margin, improvements on<br />
the baffle plate design are<br />
necessary so that free surface<br />
velocity can be reduced further.<br />
In the present work, the effect<br />
of various baffle plate geometry<br />
on the hydraulics of the<br />
SAMRAT model hot pool was<br />
investigated numerically using<br />
PHOENICS code.<br />
A 90 0 sector model of hot pool<br />
in cylindrical coordinate system<br />
Baffle Plate<br />
Fig.1 Flow pattern in hot pool with simple ring type baffle plate<br />
with one IHX and half pump<br />
was considered <strong>for</strong> analysis to<br />
as steps. The IHX is modelled as<br />
hollow cylinder.<br />
reduce the computational time.<br />
The computational domain is<br />
subdivided with a grid structure<br />
of 69 X 77 X 74 (total 3,<br />
93,162) cells to achieve fairly<br />
accurate results independent of<br />
grid. Fixed mass flow rate is<br />
provided as the inlet boundary<br />
condition at Fuel, Blanket,<br />
Experiment was carried out<br />
with simple ring type baffle<br />
plate geometry. The numerical<br />
results were compared with<br />
these experimental results and<br />
a fair agreement was observed.<br />
Fig.1 shows the flow pattern in<br />
hot pool with ring type baffle<br />
Storage and Cavity zone. The plate geometry(without any<br />
skirt is modelled as porous porosity).The numerical results<br />
plate. Flow through Control <strong>for</strong> different baffle plate<br />
Plug based on experimental<br />
measurement is modelled by<br />
specifying mass sink at the<br />
bottom of the CP and flow is<br />
considered to enter the hot<br />
configurations analysed are<br />
presented in Table 1. The<br />
results show that there is little<br />
incentive in adopting a complex<br />
geometry of baffle plate as the<br />
pool uni<strong>for</strong>mly at different reduction in free surface<br />
levels of the CP. All the velocity is minimal. This may be<br />
structural components in hot<br />
pool are modelled by blocking<br />
due to the fact that the minor<br />
variations in the baffle plate<br />
the cells at corresponding geometry do not have<br />
locations. The conical portion<br />
of the inner vessel is modelled<br />
dominant influence on the<br />
global flow patterns.<br />
36 R&D FOR FBRs
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