Civil Engineering Reference
In-Depth Information
- reactor core cooling during operational shutdown as well as under accident
conditions (loss of coolant)
- heat removal from the core flooding pools and the pressure suppression water in
case of pressure relief conditions or loss of the main heat sink
- water transfer operations prior and after core refueling operations.
3.3.2.8 Systems for Control of Severe Accidents
Because of the above described passive cooling systems, high pressure water
injection systems as in other BWRs are no more needed for the SWR-1,000
(KERENA).
Severe core melt accidents could occur if all active and passive injection
functions would fail. This is extremely improbable. In this case a core melt under
high pressure in the reactor pressure vessel can be ruled out by the design of the
depressurization system. If the reactor core melts at low pressure it could be kept in
the lower part of the pressure vessel and be cooled by water from the outside by
thermal conduction through the remaining steel structures in the lower part of the
reactor pressure vessel (Fig.
3.28
). A special flooding system can flood water from
the core flooding pools to the lower part of the drywell. A water pool surrounds the
lower part of the pressure vessel. Steam arising from cooling of the reactor pressure
vessel would be condensed at the containment cooling condensers. The heat would
be transferred to the shielding/storage pool above the inner containment.
3.3.2.9 Auxiliary Cooling Systems
The water pool for spent fuel elements is cooled by four heat exchangers operating
in the natural convection mode. Reactor water and spent fuel pool cleanup systems
with filters operate to keep the cooling water always at specified conditions.
3.3.2.10 Emergency Power Supply
An external grid supplies emergency power for all electrical loads which have to
remain available even in the event of a loss of the normal auxiliary power supply
grid. Emergency diesel generators or gasturbine-generators can take over in the
emergency case and provide an independent power supply.
3.3.2.11 Containment System
A reinforced concrete containment (Figs.
3.22
and
3.24
) encloses and protects the
inner containment against such external events as they were described for the PWR
in Sect.
3.2.4
. The annulus between the outer concrete shield building and the
