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Investigation into the Viability of a Passively Active Decay Heat Removal System In ALLEGRO. Laura Carroll, Graduate Physicist Physics & Licensing Team, AMEC MSc Physics & Technology of Nuclear Reactors University of Birmingham. Introduction: My Project at a Glance.
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Investigation into the Viability of a Passively Active Decay Heat Removal System In ALLEGRO Laura Carroll, Graduate Physicist Physics & Licensing Team, AMEC MSc Physics & Technology of Nuclear Reactors University of Birmingham
Introduction: My Project at a Glance • To assess a proposed modification of a safety feature of a new type of reactor • Use of RELAP5/MOD3 • Steady State (normal operation) • Loss Of Forced Cooling (LOFC) transient (accident scenario) • ALLEGRO: experimental demonstration reactor for the Gas Cooled Fast Reactor Countries we work in
The Gas Cooled Fast Reactor • 1 0f 6 designs chosen by Generation IV International Forum (GIF) • Fast spectrum • Helium coolant • High outlet temperature • High power density
Residual Heat; the need for constant cooling post shutdown • Once a reactor is shut down, its power will fall to approximately 7% of full power and then reduces exponentially thereafter. • The Decay Heat Removal (DHR) system exists to remove this residual heat from the reactor core. • It is currently activated after a reactor trip by a valve sequence
Loss of Forced Cooling Transient: Existing Design • After 10s Blower begins to run down • The reactor is shut down • When mass flow rate reaches 3% of its original flow, main loop valve closes • Simultaneously, DHR loop valves open
Modification: Direct connection and Stratification of Upper Plenum
Conclusions • Results are not ideal • Clad temperatures not as terrible as initially feared • Stratification of Upper Plenum showed great improvement on previous modifications • Substantial Potential for future Research and Development in this area
Further Investigations • Develop a removable Decay Heat Removal system heat sink • Add a fluidic diode
For more information… A Technology Roadmap for Generation IV Nuclear Energy Systems Dec 2002 U.S DOE Nuclear Energy Research Advisory Committee http://www.world-nuclear.org/info/inf77.html Vortex Diode Pumps: No Moving Part Pumping Systems, NuVision Engineering http://www.nuvisioneng.com/uploads/VortexDiodeProfile.pdf Thank you… Any Questions?
LOFCresults • Region of Blower run down • Establishment of Natural Convection • Natural Convection