Civil Engineering Reference
In-Depth Information
Fig. 3.6
Isometric view of
the reactor coolant system
US-APWR [
5
]
In the steam generators heat is transferred through a large number of tubes
(Fig.
3.7
). Feed water at a pressure of about 7 MPa is evaporated and steam is
passed through separators to remove water droplets and attain a moisture content of
less than about 0.015 %. In the steam generator, the primary coolant system is
separated from the secondary coolant system by the tubes. The EPR steam gener-
ator (Fig.
3.7
) with economizer makes it possible to reach a saturation pressure of
7.8 MPa by special guidance of the feed water flow. This leads to a thermal
efficiency of up to about 36 % (EPR) [
4
].
The steam flows through the turbine valves (Fig.
3.1
) into the high pressure
section of the turbine and, after reheating, into the low pressure section of the
turbine. The expanded steam is precipitated in the condenser and pumped back as
feed water by the main condensate pumps into the feed water tank. The main feed
water pumps move the pressurized water from the feed water tank through four
main feed water pipes into the four steam generators.
In case the turbine would have to be suddenly disconnected from the grid as a
result of some fault condition, steam can be directly passed into the condenser by
means of bypass valves. If the condenser should not be available due to some
failure, the steam can be blown off to the atmosphere by means of blow down
valves and safety valves.
