Combustion Engineering (CE) Reactor Protection System (RPS)

The Combustion Engineering RPS is a complex control system comprising numerous electronic and mechanical components that combine in the ability to produce an automatic or manual rapid shutdown of the nuclear reactor, known as a reactor trip or scram. In spite of its complexity, the Combustion Engineering RPS components can be roughly divided into four segments-channels, trip matrices, trip breakers/relays/contactors, and control rods.

The RPS system consists of four identical protective channels. Each protective channel contains between ten and sixteen measurement channels, each capable of initiating protective actions by actuating a bistable. Each bistable includes three relays (included within the bistable component). The relay contacts are in three of the six logic matrices combined with relay contacts from one other channel in a two-out-of-two logic. When enough channels trip, the logic matrix de-energizes. This removes power from the four matrix output relays. The four output relays open contacts supplying power to relays, which control power to the undervoltage devices and shunt trip mechanisms in the reactor trip breakers.

The initial system study is documented in "Reliability Study: Combustion Engineering Reactor Protection System, 1984-1998" (NUREG/CR-5500), Volume 10. The links below provide the current information for the study and latest results.

Current Results:

• CE-RPS 1998 Summary Results

Supporting Information:

• CE-RPS Description
• CE-RPS Fault Tree

Historical Results:

• "Reliability Study: Combustion Engineering Reactor Protection System, 1984-1998" (NUREG/CR-5500), Vol. 10