Civil Engineering Reference
In-Depth Information
Fig. 10.13
Cooling of
molten core by flooding the
reactor pressure vessel with
water on the outside [
75
]
Core melt
(oxide
fraction
vessel of SWR-1000 can be flooded passively by water from the flooding pools. In
addition to cooling of the molten core in the lower head by outside flooding of the
pressure vessel, there exists the backup possibility of retaining molten fuel (if it
would melt through the bottom of the reactor pressure vessel) by a special steel
support plate underneath. This support plate fixes the control rod drives in the
bottom hemispherical head of the reactor pressure vessel. It can act as a back-up
core catcher in case parts of the core would melt through the bottom head [
75
,
77
].
The decay heat (afterheat) of the core melt can be transferred by evaporating
water. The resulting steam can be cooled and condensed by the containment cooling
condenser [
75
,
77
] (Fig.
10.14
).
10.3.6.2 Penetration of the Core Melt Through the Bottom Head
of the Reactor Pressure Vessel
The second safety design option e.g. realized in EPR, is to keep the reactor cavity
dry (no flooding with water) and to install a molten core fuel retention and cooling
device (core catcher) outside of the reactor pressure vessel [
67
,
68
]. This design will
be described for EPR in Sect.
10.3.7
.
Core Melt Through in Case of Presently Operating LWRs
For presently operating LWRs, having no molten core retention device core catcher
the situation will be different. This will described e.g. for the PWR1,300 design.
