86 F. KOPPENBORG
might fail (e.g., that an earthquake might cut off external electricity
supply). Omitted were measures against severe accidents where more than
one component within the reactor might fail, as was the case with the
Fukushima nuclear power plant where off-site power supply was cut off
by the earthquake and back-up generators were destroyed by the tsunami.
One way the NRA has chosen to implement this is by strengthening
the reactor design basis, which designates the construction design a new
reactor should adhere to in order to withstand predefined threats. New
standards require a seismic ground motion assessment for each nuclear
power plant in order to determine the specific level of earthquake resistance required for the plant. Volcanoes within a 160-km radius are to
be surveyed to assess the risk and that appropriate measures are to be
taken. Mandatory tsunami protection walls need to exceed the largest
one ever recorded for the area. Strengthened design basis requirements
are meant to prevent the nuclear power plant from being damaged by a
natural disaster in the first place. In case they prove insufficient, severe
accident countermeasures are in place to prevent a nuclear disaster like
the one at the Fukushima Daiichi power plant.
The idea of defence-in-depth is also represented in severe accident countermeasures. Such countermeasures address both natural phenomena and
other events. Natural phenomena are defined to include earthquakes,
tsunamis, volcanic eruptions, tornadoes, and forest fires. Events other
than natural phenomena refer to events such as a fire inside a reactor,
internal flooding, power supply failure, and the like. Severe accident countermeasures include the installation of waterproof doors and fire-proof
cables, and the preparation of switchboards for operating the plant in
diverse locations. Measures to increase the reliability of off-site power
sources prescribe connecting two or more power substations with at least
two transmission lines to ensure they remain functional even if some of
the stations and some of the power lines are damaged. This off-site power
supply is further supplemented by mobile power units placed on a hill
nearby. Measures to strengthen capacities to cool parts of the nuclear
power plant such as a spent fuel pool or a reactor itself focus on the
use of mobile water injection systems as well as permanently installed
water injection systems. To prevent hydrogen explosions at boiling water
reactors, there needs to be filtered venting system to let out hydrogen
if needed to reduce pressure within a reactor. Another novelty is the
requirement of an extra control room that is located on higher ground
and is radiation-proof to a certain degree. Next to introducing a back-fit
might fail (e.g., that an earthquake might cut off external electricity
supply). Omitted were measures against severe accidents where more than
one component within the reactor might fail, as was the case with the
Fukushima nuclear power plant where off-site power supply was cut off
by the earthquake and back-up generators were destroyed by the tsunami.
One way the NRA has chosen to implement this is by strengthening
the reactor design basis, which designates the construction design a new
reactor should adhere to in order to withstand predefined threats. New
standards require a seismic ground motion assessment for each nuclear
power plant in order to determine the specific level of earthquake resistance required for the plant. Volcanoes within a 160-km radius are to
be surveyed to assess the risk and that appropriate measures are to be
taken. Mandatory tsunami protection walls need to exceed the largest
one ever recorded for the area. Strengthened design basis requirements
are meant to prevent the nuclear power plant from being damaged by a
natural disaster in the first place. In case they prove insufficient, severe
accident countermeasures are in place to prevent a nuclear disaster like
the one at the Fukushima Daiichi power plant.
The idea of defence-in-depth is also represented in severe accident countermeasures. Such countermeasures address both natural phenomena and
other events. Natural phenomena are defined to include earthquakes,
tsunamis, volcanic eruptions, tornadoes, and forest fires. Events other
than natural phenomena refer to events such as a fire inside a reactor,
internal flooding, power supply failure, and the like. Severe accident countermeasures include the installation of waterproof doors and fire-proof
cables, and the preparation of switchboards for operating the plant in
diverse locations. Measures to increase the reliability of off-site power
sources prescribe connecting two or more power substations with at least
two transmission lines to ensure they remain functional even if some of
the stations and some of the power lines are damaged. This off-site power
supply is further supplemented by mobile power units placed on a hill
nearby. Measures to strengthen capacities to cool parts of the nuclear
power plant such as a spent fuel pool or a reactor itself focus on the
use of mobile water injection systems as well as permanently installed
water injection systems. To prevent hydrogen explosions at boiling water
reactors, there needs to be filtered venting system to let out hydrogen
if needed to reduce pressure within a reactor. Another novelty is the
requirement of an extra control room that is located on higher ground
and is radiation-proof to a certain degree. Next to introducing a back-fit