Civil Engineering Reference
In-Depth Information
Fig. 3.11
Containment heat removal system in case of core melt for EPR (AREVA) [
4
,
8
]
3.2.5 AP1000 Safety Design
The containment design of the AP1000 (Table
3.2
) relies on passive safety features,
e.g. natural driving forces like gravity flow, natural circulation flow and convection
heat transfer, as well as compressed gas.
The AP1000 containment (Fig.
3.12
) consists of an outer cylindrical reinforced
concrete shield building which surrounds a cylindrical steel containment of 39.6 m
diameter. During normal operation and accidental conditions the concrete shield
building provides shielding against radiation from reactor components and released
radioactivity. It also protects the internal reactor components from external
impacts, e.g. tornados, missiles, etc. [
2
,
10
].
In case of a core melt accident followed by heat and vapor release to the inner
atmosphere of the containment the heat can be transferred by thermal conduction
through the steel wall of the internal containment. Air coming into the shield
containment structures flows down a baffle structure and cools the cylindrical
steel wall by uprising natural convection flow (Fig.
3.12
). It leaves the shield
containment at the top. This cooling process can be enhanced by water flowing
from the drain tank of the passive containment cooling system (PCCS) on top of the
inner steel containment. This water is flowing down the outer surface of the inner
steel containment. The in-containment refueling water storage tank (IRWST) with
its large water volume provides a large heat sink for passive residual heat removal.
