Enhanced Steam Pressure Control Routine for SOPHT-PA (Simulation of Primary Heat Transport -Pickering Nuclear Generating Station A)

Abstract

Operating experience at Pickering Nuclear Generating Station A revealed that following a fast turbine load rejection with turbine inlet pressure signal irrational, fast boiler pressure control action would not necessarily prevent a reactor trip. A change was proposed to the fast boiler pressure control steam reject valve control algorithm to provide better unit response to such events. To evaluate the proposed change, the boiler pressure control routine in the SOPHT computer code had to be revised. The upgraded SOPHT computer code was successfully verified by comparison with an actual station transient. The investigation did not reveal any negative reactor safety implications resulting from the proposed change to fast boiler pressure control. The proposed change would improve electrical generation capability and would make a fast turbine load rejection event less stressful.