The Development of Trip Coverage Maps for the McMaster Nuclear Reactor

Abstract

<p>Trip coverage maps indicate the reactor conditions under which instrument devices, manual scrams or passive safety systems are capable of arresting reactor transients initiated by specified postulated accidents before reaching safety boundaries. Trip maps are developed by simulating reactor transients with appropriate codes such as the PARET/ANL code. PARET/ANL has been validated against SPERT transient data with favorable results and is particularly suited for research reactor simulation of MTR reactors like the McMaster Nuclear Reactor (MNR).</p> <p>A conservative PARET/ANL model of MNR has been developed by considering the characteristics and operating limits of the MNR core. Conservative conditions of accident scenarios were adopted and PARET/ANL was used to simulate these conditions in MNR. During these P ARET power excursion simulations the MNR engineered safety system responses to loss of regulation rod control, sample handling and fuel handling accident scenarios were assessed and trip coverage maps were developed for each accident category. Forced convection and natural convection reactor conditions were considered.</p> <p>The PARET/ANL model of MNR predicts at least one engineered safety system is capable of arresting transients initiated from high power conditions (0.1 - 5.0 MW) in all the accident scenarios considered, -before the onset of bulk boiling. The model predicts at least one system prevents transients from reaching these thermal limits during transients initiated from low power conditions «0.1 MW) during loss of regulation rod control events. The withdrawal of SSR from low power conditions induce transients which may progress to bulk boiling in the hottest fuel channel. Fuel handling accident induced transients from a shutdown state are predicted to be arrested by the <3.8 s period scram and both 125% high flux scram instrument channels before thermal limits are reached.</p>