Characterizing the Bistable Flow, of BWR, as a Bifurcation (Pitchfork Type) in the Navier-Stokes' Equation Solution

Dr. Carlos J. Gavilan Moreno

Bifurcation, pitchfork, bistable, recirculation, FCV, flow.

Many nuclear power plants have undertaken power uprate processes, increasing recirculation, feed water and steam flow rates. With regards to recirculation flow, adverse scenarios,may arise where the flow varies autonomously between two values, a phenomenon known as bistable flow.Although this phenomenon is typically related to power uprate processes, some plants experience it when they reach high flow values, especially at the end of the cycle. This study proves empirically the existence of a Pitchfork-type bifurcation in the bistable flow situation.The parameter determining bifurcation will be Flow Control Valve (FCV) position in recirculation loop. This choice is made considering that it is the only variable during recirculation loop operation, because under stable operation and constant power the remaining variables (Geometry, Combustible, Differential Core Pressure, Pump Turning Speed (r.p.m.), etc.), are considered constant.

10.22161/ijaers/3.11.10