Containment vessel cooling system having the following components: • a sealed containment vessel for a nuclear installation, • a cooling medium-collecting region situated within the containment vessel and serving for receiving a medium to be cooled , • a first heat exchanger situated within the containment vessel and serving for the exchange of heat between the medium to be cooled and a coolant, • first means for extracting the medium to be cooled from the cooling medium-collecting region , supplying said medium to the first heat exchanger for the purpose of cooling, and, after it has flowed through the latter, returning said medium to the cooling medium-collecting region , in a first cooling circuit , wherein the first means have a first pump apparatus , situated within the containment vessel , in order for the medium to be cooled to be made to flow, • second means for supplying the coolant from outside the containment vessel to the first heat exchanger , and, after it has flowed through the latter, returning said coolant to outside the containment vessel , wherein the second means have a second pump apparatus , situated outside the containment vessel , in order for the coolant to be made to flow, wherein the second means have a turbine which is situated within the containment vessel and which is driven by the flow of the coolant, and the first pump apparatus is coupled to the turbine so as to be driven by the latter, characterized • in that the turbine and the first pump apparatus are arranged within the cooling medium-collecting region and, during operation, below the surface of the medium to be cooled . • a sealed containment vessel for a nuclear installation, • a cooling medium-collecting region situated within the containment vessel and serving for receiving a medium to be cooled , • a first heat exchanger situated within the containment vessel and serving for the exchange of heat between the medium to be cooled and a coolant, • first means for extracting the medium to be cooled from the cooling medium-collecting region , supplying said medium to the first heat exchanger for the purpose of cooling, and, after it has flowed through the latter, returning said medium to the cooling medium-collecting region , in a first cooling circuit , wherein the first means have a first pump apparatus , situated within the containment vessel , in order for the medium to be cooled to be made to flow, • second means for supplying the coolant from outside the containment vessel to the first heat exchanger , and, after it has flowed through the latter, returning said coolant to outside the containment vessel , wherein the second means have a second pump apparatus , situated outside the containment vessel , in order for the coolant to be made to flow, wherein the second means have a turbine which is situated within the containment vessel and which is driven by the flow of the coolant, and the first pump apparatus is coupled to the turbine so as to be driven by the latter, characterized • in that the turbine and the first pump apparatus are arranged within the cooling medium-collecting region and, during operation, below the surface of the medium to be cooled . <EOS>