Grant: Engage Grants Program

Large Break Loss of Coolant Accidents (LB LOCA) are defined as those with the loss of coolant rate of 3000 kg s^-1 or higher. Rapid coolant voiding leads to an overpower transient for reactors having positive void reactivity and subsequent possible fuel centreline melting, fuel cladding failure, and possible loss of integrity of fuel channels. Peak reactivity should not exceed the prompt criticality threshold to prevent uncontrolled increase of reactivity and reactor power [1].For the CANDU reactors, PWRs, and, as applicable, for high temperature Generation IV reactors, several options have been evaluated for the potential improvement of reactor power measurements during steady state operation and during reactor transients. Reactor power regulation, reactivity control and reactor trips in the existing design are mainly based on neutronic power signals that are susceptible to signal noise and electromagnetic interference (EMI). False (spurious) channel trips may cause a reactor to trip in certain scenarios resulting in loss of generation. With the combination of selected reactor process parameters and measurement of gamma and thermal neutron fluxes, better control of the reactor power (including spatialpower), with a reduced probability of false trips, can be achieved. In the case of a LB LOCA transient, faster reactor trips will decrease the duration of, or fully eliminate a prompt criticality even in reactors with a positive void reactivity coefficient. The proposed project will provide practical solution to ensure safer CANDU nuclear power plants during LOCA events without the need of additional software or firmware, which will provide easy implementation based on the proposed signal processing and trip logic techniques. Almost all the components required in this solution will be based on existing reactor instrumentation, without any modification to the reactor systems.