Overview of Requirements and Current Design - The Risks of Nuclear Energy Technology - page 240

rather — comparable to the requirements according to the RSK-LL—allocated to
security level 4. These are very rare events which the design of the facility must
account for to limit the effects of accidents. Considerable releases to the environ-
ment are to be avoided. The protection goal of the enclosure of radioactive materials
is to be ensured by maintenance of the integrity of the reactor coolant pressure
systems and the inner steel containment. All systems necessary to control the event
sequences must be appropriately designed.
All structures of the buildings must meet the minimum requirement for load
bearing capacity. Unlike with security level 3 (e.g. earthquakes), the building is not
required to be fully functional after an aircraft impact. Cracking and irreversible
deformation are permitted, so long as safety-relevant issues are not affected. For
reasons of structural stability or functional capability of facility components,
additional requirements which go beyond the minimum requirements for loading
bearing capacity (e.g. limitation of deformation and width of cracks) might be
necessary at defined points.
According to the BMU safety criteria (cf. [ 3 ]), the effects of debris, kerosene
fires, kerosene explosions and additional consequences are to be respected when
considering a postulated airplane crash. In particular, this includes:
• Kerosene fire on the facility compound
• Explosion of the kerosene inventory (partially or entirely) outside of buildings
• Fire or explosion of kerosene (liquid or vaporized) which has entered buildings
due to permanent existing openings or those caused by the crash
• Entry of combustion products and supply air with reduced oxygen content as a
consequence of combustion processes into the ventilation system with respect to
human actions, electrical equipment and supply air for diesel generators.
The requirements correspond to the BMU safety requirements [ 4 ] and are
compiled in the “Handbook for reactor safety and radiation protection”
(RS-Handbook) ([ 1 ] of Chap. 11 ) which is continuously updated.
12.3 Development of the Design in Germany
Dependent on the chronological order of their construction German nuclear power
plants were, with the exception of the very first ones, designed with increasing
higher standards with respect to an accidental “random” airplane crash of a certain
type. Specific aircraft models were chosen to represent the particular effects and
were the basis of the design standards for structures and components.
Three groups of German nuclear power plants can be distinguished with respect
to their resistance against the external event of an airplane crash according to the
corresponding start of construction:
• a first group, which does not feature a systematically planned resistance to
airplane crashes