IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
minimum value. Detailed 3-D
hydraulic investigations have
been carried out to arrive at a
compact layout for the supply
and discharge headers of the
SVSE cooling circuit satisfying
the design and layout
requirements. With the
acceptable number of headers
(4) and header size (40 NB),
there are 36 tubes connected
to each header. The flow
distribution was highly nonuniform
in the "end-in & endout"
configuration. In the
"central-in & central-out"
configuration, with orifices in
the tubes and 20 % extra flow
in the circuit, the required flow
could be achieved with
minimum pressure drop in the
system. The "end-in & end-out"
header configuration and the
flow distribution in the modified
configuration are depicted in
Fig. 3 and 4 respectively.
Fig. 4 Flow distribution in the SVSE
cooling loop
II.4. Structural Integrity of Grid Plate under Accidental Fall
of Subassembly with Transfer Arm
PFBR core consists of 1758
subassembiles (SAs) including
181 fuel subassemblies (FSA),
120 blanket subassemblies
(BSA), 9 control subassemblies
(CSA), 156 storage
subassemblies (SSA) and the
remaining
shielding
subsassemblies. Each SA has a
circular foot at the bottom, that
is inserted in to the respective
sleeve and thus the core SAs
are free standing on the grid
plate, behaving like a cantilever
beam. Grid plate(GP), apart
from supporting the SAs, acts
as a plenum to distribute the
required amount of sodium
coolant to the SAs. Thus, the
grid plate does the important
safety function in the reactor
and hence, it is designed
respecting the RCC-MR class 1
component rules. As per the
design criteria, the structural
integrity is ensured under all the
operating conditions including
postulated accident scenarios.
Analysis had been carried out
to demonstrate the structural
integrity of grid plate under
impact force developed due to
the free fall of a single SA
along with gripper of transfer
arm (TA), during the handling
operation.
Impact scenario
Within the reactor assembly, the
SAs are handled by transfer arm
(TA) for the three major
operations: (1) introduction of
fresh SA in to the respective
location in grid plate after
removing from the transfer pot
(TP), (2) transfer of spent fuel
Fig.1 Schematic of gripper
assembly and SA
16 PROTOTYPE FAST BREEDER REACTOR