IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
510 0 C –
Tube Flow fluctuation
Steam Temperature fluctuation at tube outlet
460 0 C – 0 bar
Steam outlet Pressure fluctuation
SG inlet flow fluctuation
Fig.2 Instability build-up
fluctuations (10-20 K) in observed at the output of the
temperature readings are differential pressure transmitters
observed (Fig.2). Fluctuations, connected across the orifices
periodic in nature were during the instability
phenomenon.
Fig.2 also shows the variation
of both the thermocouple
output and the differential
pressure transmitter output for
a tube. Similar pattern of
oscillation is observed in other
tubes also. Oscillations
observed in flow, in tubes were
found to be in the same phase.
A similar trend is also observed
in the module feed water inlet
flow to SG during instability.
The above has indicated the
feasibility of an instrumentation
scheme for on-line
measurement of dynamic
instability in once through
Steam Generator in an
operating plant through flow
fluctuation in overall module
flow.
III.B. Sodium Technology
III.B.1. Sodium Cleaning of FBTR Dummy Subassembly by Steam-Nitrogen
Process Using In-house Developed Hydrogen Sensor (PEMHS)
Sodium cleaning method based
on steam-nitrogen is a simple
and effective process. Residual
sodium sticking to the fuel sub
assemblies (FSA) received at
Head End Facility (HEF) from
FBTR and its reaction products
with air are likely to interfere
with chopping process. Hence
the residual sodium has to be
removed. Sodium cleaning is
carried out in HEF by
steam/nitrogen process. To
gain experience in sodium
cleaning of FSA by
steam/nitrogen process and to
optimize the process
parameters, the mock-up
sodium cleaning experiment
was carried out in an in-house
developed system.
The sodium cleaning process
involves following steps.
1. Steam cleaning: Removal of
adhering sodium by reaction
with steam carried by nitrogen.
38 R&D FOR FBRs