Technology and Operation - Kernkraftwerk Gösgen

Reactor coolant system
Steam generators
The three steam generators transfer the heat
from the reactor coolant to the water/steam
circuit. Designed as standing U-tube heat exchangers,
they convert feed water into live
steam to drive the turbo-generator system.
The collection chamber is connected to the
reactor coolant circuit pipes via inlet and outlet
nozzles. The reactor coolant flows out of
the collection chamber and through the Utubes
to the outlet chamber, giving off heat as
it flows. From the outlet chamber, the coolant
is directed to the primary coolant pump. The
bundle of U-tubes, made of an exceptionally
corrosion-resistant material, is supported at
a large number of points and is rolled into
and welded onto the steam generator’s tube
plate.
The incoming feed water flows downwards by
natural circulation between the vessel wall
and a shroud surrounding the tube bundle
before moving upwards again, giving off
steam, once it has absorbed the heat. In the
steam dome above the tube plate, the residual
steam moisture is separated off before
the dried steam is eliminated through the
outlet nozzle.
Pressuriser
The purpose of the pressuriser is to keep
the operating pressure in the reactor coolant
system constant. A change in the reactor
power produces variations in the temperature
and volume and, without a pressuriser,
these would lead to pressure fluctuations.
The pressuriser is an upright container with
a capacity of 42 cubic metres, which is partly
filled with water. It is connected up to one of
the three reactor coolant loops via the pres-
Steam generator
suriser surge line. Pressure control is performed
by means of an electric heater in the
water section of the pressuriser and a facility
for spraying water into the steam section.
Using the spray system, the steam can be
condensed and hence the pressure reduced.
By generating heat with the electric heater
rods, water can be evaporated and hence
the pressure raised.
Steam outlet
Steam dryers
Manhole
Steam separators
Feedwater inlet nozzle
Feedwater ring line
Heating tubes
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Shroud
Vessel
Tube support grids
Hand hole
Support and guide brackets
Tube sheet
Reactor coolant inlet
Reactor coolant outlet