The stability of boiling water reactors as a catastrophe phenomenon

Paper in proceeding, 2015

The stability of boiling water reactors (BWRs) is revisited in terms of catastrophe theory. The hypothesis is proposed that the stability parameter (decay ratio) of a complex, many-variable non-linear system might obey a cusp catastrophe. The incentive for this surmise comes from indications in real measurements that in certain cases the decay ratio appears to behave discontinuously and might show a hysteresis as a function of the control parameters reactor power and coolant flow. Such observations can be explained by a phenomenological catastrophe model suggested in this article. Since a cusp-type behaviour implies that the decay ratio is many-valued in a certain region of the power-flow map, a mechanism is suggested how a Hopf bifurcation with multiplicative noise can lead to such a behaviour.