Emergency Operating Procedures Based on Thermodynamic State

Abstract

Since the TMI-2 accident in 1979, all western countries with significant nuclear electricity supply programmes have recognized the benefits of a symptoms oriented approach for operator reaction and response to severe plant upsets. The development of Emergency Operating Procedures (EOP) for the Point Lepreau station has followed a complementary two track structure, both tracks having a thermodynamic state basis. One track deals with plant upsets where the nature of the cause of the upset is recognized and an Event Specific EOP exists for that cause. The second track caters to upset conditions where a) the Critical Safety Parameters are outside defined acceptable values or b) the Critical Safety Parameters are trending towards their unacceptable limits and i) the cause of the event is not recognized or ii) the cause is recognized but no Event Specific EOP exists. Event Specific EOP structure and format are discussed and illustrated and the Critical Safety Parameters associated with developing the second track for boiler heat sink configurations are discussed.