Babcock & Wilcox (B&W) Reactor Protection System (RPS)

The Babcock & Wilcox RPS is a complex control system comprising numerous electronic and mechanical components that combine to provide 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 Babcock & Wilcox RPS components can be roughly divided into four segments-channels, trip modules, trip breakers/diverse trip, and control rods.

The RPS trips the reactor by removing holding power from the control rod drive motors (CRDMs). Each holding power supply receives dc power from a Main and a Secondary power source. In order to release the rods, both the main and secondary power supplies must be interrupted. This is accomplished by either; opening trip breakers on both power supplies or by removing gating power from the silicon-controlled rectifiers (SCRs) (gating power controls the operation of the SCRs to move or hold the rods).

The initial system study is documented in "Reliability Study: Babcock & Wilcox Reactor Protection System, 1984-1998" (NUREG/CR-5500), Volume 11. The links below provide the current information for the study and latest results.

Current Results:

• BW-RPS 1998 Summary Results

Supporting Information:

• BW-RPS Description
• BW-RPS Fault Tree

Historical Results:

• "Reliability Study: Babcock & Wilcox Reactor Protection System, 1984-1998" (NUREG/CR-5500), Vol. 11