Technology and Operation - Kernkraftwerk Gösgen

Containment venting system
1 Containment isolation valves
2 Rupture disk
3 Scrubber unit
4 Venturi
5 Scrubbing water
6 Metal-fibre filter
7 Throttle
8 Piping penetrations of
the containment
Inside
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Steel containment
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2
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Annulus
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ing characteristic process parameters, including
pressure, temperature, neutron flux
and activity. If safety-related threshold values
are exceeded or not attained, the reactor protection
system shuts down the reactor before
the design limits are reached. It registers malfunctions
and, if necessary, sends signals to
the emergency systems to trigger their active
intervention, such as the closure of the building
isolation valves or the start-up of the
emergency cooling systems.
The reactor protection system includes the
full range of devices and installations necessary
for triggering protection measures, from
the instrumentation, via the logic component,
right through to the control level.
At least two physically different process parameters
are taken into account for triggering
protective measures. These are conveyed via
instrumentation lines from the measuring
points to the transmitters, where they are
converted into analogue signals which are
then taken up by the limit-value units. These
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Vent stack
M
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Nuclear auxiliary building
Safety precautions
compare the measured values with the specified
limit values and convert them into the
binary signals of «allowed» or «prohibited»
before transmitting them to the logic component.
There, they are linked together in
such a way that the necessary commands
are generated for each protective function
from a predefined set of signals.
Safety review
Periodic, comprehensive safety reviews are
carried out in order to assess the safety of
Switzerland’s nuclear power plants. These
periodic reviews permit an overall assessment
of the plant’s current safety status. They
take into account all the available results and
the experience acquired from routine inspections,
tests, recurring checks, safety
analyses and operational experience.
The safety concept developed for nuclear
technology is based on hypothetical incidents
and engineering experience. It is laid
down in laws, decrees, rules, guidelines and
recommendations, including those governing
the design of components and fire protection.
Probabilistic safety and risk analyses (PSAs)
have also been developed for verifying the
design. These have now become established
in practice for assessing nuclear power
plants. A PSA permits reliability assessments
for safety-relevant systems to be conducted
on the basis of the ascertained probabilities
of failure. In addition to this, complex accident
sequences involving the failure of safety
sub-systems can be analysed with the aid of
probability considerations. Risk analyses include
the assessment of possible damage
outside the plant. A comprehensive PSA was
carried out for the KKG in 1993. The study
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