furthermore, each reactor unit has been equipped with an emergency building (nano, "nachrüstung notstandsystem"). these contain additional safety systems for the reactor emergency shutdown and for the feeding of the steam generators, a 50 kv emergency power line, and a diesel electricity generator. they are heavily protected (bunkerised) from external hazards and, if needed, are able to cool and shut down the power plant without human intervention for 72 hours. the at least 1.5 m thick concrete-steel housings protect the critical systems from external agents like earthquakes or plane crashes. each unit of the kkb has a "large dry" type containment in steel and concrete.