Design of KWU LWR safety systems

In the 10 years of development which lie between the design of the 300 MWe Obrigheim plant and the KWU Standard 1300 MWe PWR of today, the engineered safeguards were extended to cope with an enlarged variety of anticipated accidents. The KWU Safety System meets these demands with proven principles of the protection system, of software and hardware: protective functions which must be actuated within half an hour are automated and are independent from normal control, so that no action of the operator is necessary except to implement long-term protective procedures. Two random failures must not jeopardize reactor power trip capability nor shall a spurious failure trip the reactor or lead to more than one safeguard actuation if such action is not clearly oriented towards safety. Redundant sub-systems are installed in separate rooms in the reactor building and the control room building. In order to be protected from external events, such as a plane crash or gas explosion, parts of the electrical and mechanical equipment, including an emergency control room, are protected by reinforced concrete buildings. The core is protected against flux tilts by quick responding and accurate in-core instrumentation which, coupled with a local power distribution control system, reduced integral reactor power prior to reaching intolerable Fsub(q) values. Many years of operational experience with power reactors and an efficient quality control system have led to highly reliable mechanical and electrical safety equipment, which assures highly satisfactory values of safety and availability for all KWU nuclear power plants