The Design of Light Water Reactors - The Risks of Nuclear Energy Technology - page 60

Fig. 3.22 Schematic view of the inner and outer containment of BWR-1,300 (Kraftwerk Union)
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3.3.2.1 Pressure Suppression System of Kraftwerk Union BWR-1,300
Figure 3.22 shows the pressure suppression containment system of the Kraftwerk
Union BWR-1,300. The reactor pressure vessel, the recirculation system and the
pressure relief valves of the main steam pipes are accommodated in the inner
containment, also called drywell, which isolates them from the rest of the reactor
containment. The drywell consists of a reinforced concrete structure with horizontal
vent openings which allow communication between the pool and the drywell. The
drywell is kept dry.
If primary coolant is released through a leak in the primary system pipes, steam
will enter into the drywell and will be channeled into the pressure suppression pool,
where it will condense. An inner containment surrounds the drywell pressure
suppression system and all reactor equipment. It is designed to withstand temper-
atures and pressures that could be caused by a loss-of-coolant accident and to retain
non-gaseous fission products which could potentially be released from the reactor
system during an accident.