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In the top portion of the shell of the tube
system there are inlet windows for the heat-
ing coolant.
The tube system of the steam generator
operates as follows: Primary coolant is fed
into the steam generator from the reactor
through the inner tube. The coolant flows
through the gap between the vessel and the
tube system jacket up to the top portion and
flows into the pressure chamber through the
windows. Further, the coolant is distributed
across the steam generating modules and
flows from the top to bottom in the annular
space transferring heat to secondary fluid.
The coolant is drained into the cavity be-
tween the tube system jacket and the vessel
and then is headed upward through the annu-
lar gap between the inner and outer tubes and
to the suction drum of the primary coolant
pump.
Feedwater is supplied to the feedwater
headers through the feedwater supply tubes
and then flows down in the feedwater pipes
and is distributed across the heat exchange tubes. The water flows upwards in tubes of the
coils, where it is heated up to the boiling point, and turns into steam, which is then super-
heated up to required parameters. Further, the steam flows from the modules to the steam
removing channels in the head, from where it is headed to the steam lines through the
steam headers and tubes.
4.5. STEAM GENERATOR FOR VPBER-600 REACTOR UNIT
The steam generator for VPBER-600 is used to transfer thermal energy of the pri-
mary coolant to the secondary coolant.
The steam generator for VPBER-600 is designed on the basis of engineering solu-
tions providing for:
•
installation of the steam generator inside the reactor so as to fill the annular
space between the tube and device unit (TDU) and the reactor vessel to a maximum possi-
ble extent and, at the same time, to provide for the replacement of the steam generator in
the process of operation;
•
installation of the headers in the steam generator units, which supply (remove)
the secondary coolant, welding and testing of field weld seams in the reactor pipes and
tubes inside the cavity of the secondary circuit;
•
utilization of the header of the steam generator, which supplies (removes) the
secondary coolant, as a «leak arrester» for the primary coolant in case of emergencies with
leaks from the pipe, to the extent of a hypothetical accident with a complete rupture of the
pipe in the steam generator;
•
utilization of the headers in the units of the steam generator, which supply (re-
move) the secondary coolant, as a «leak arrester» for the primary coolant in case of emer-
Fig. 4.28. Steam Generator of VBER-300
Reactor Unit:
1
– Steam generator vessel;
2
– Module of the
steam generator;
3
– Steam generator head;
4
– Steam tube;
5
– Feedwater tube
