BWR RCIC Steam Inlet Valve Upgrade

Challenge

Boiling Water Reactor (BWR) units are designed with a Reactor Core Isolation Cooling (RCIC) system in order to supply the core with water in the event that coolant was unavailable through the normal feedwater lines. Steam from the main steam lines is used to supply a turbine that drives the RCIC pump. A valve is installed just upstream of the RCIC turbine stop valve to act as a block valve to keep steam from the turbine. This block valve is typically specified as a globe valve with quick-opening trim. Plant operators were consistently challenged in getting the turbine on line as too large a steam volume can cause the turbine to trip on overspeed before adequate oil pressure can be built up.

Solution

Flowserve engineers solved the problem by replacing the quick-opening trim with a set of characterized trim to provide the desired resolution in the valve trim and allow the control of the steam volume entering the turbine. This solution was accomplished without changing any logic or motor actuator gearing or timing, resulting in thousands of dollars of savings in engineering costs.