Relevant Thermal-Hydraulic Aspects in the Design of the RRR A. Doval, C. Mazufri F.P. Moreno Bariloche, Rio Negro, Argentina

Hydraulic Design Zircalloy chimney Relevant T-H Aspects in the Design of the RRR Chimney FA CP Mirror Configuration 16 Fuel Assemblies 21 Fuel Plates Vertically placed 5 Control Plates Inside Control Guide Box

Hydraulic Design (cont.) Relevant T-H Aspects in the Design of the RRR Upward Flow Enables dynamic core pressurization There is no flow inversion Avoids blockage of coolant channels Nozzle Window Comb FP Upward Flow

Hydraulic Design (cont.) - CP Relevant T-H Aspects in the Design of the RRR High enough to remove heat Internal Pressure External Pressure > Coolant velocity Low enough to avoid drag

Primary Cooling System Relevant T-H Aspects in the Design of the RRR Flap valves Inlet pipe Zr chimney Outlet pipe Core Inlet plenum PCS flow Closure flow

Primary Cooling System (cont.) Relevant T-H Aspects in the Design of the RRR

Thermal -Hydraulic Design It must ensure that Relevant T-H Aspects in the Design of the RRR Power Peaking Factor = 3 Cosine profile Extrapolated length = 8 cm  Power in the hot channel  Maximum heat flux î for every configuration î along the whole cycle Design Criteria are fulfilled

Thermal -Hydraulic Design Relevant T-H Aspects in the Design of the RRR

Design Criteria Goal : To preserve the main barrier of FP (Al cladding) Relevant T-H Aspects in the Design of the RRR To ensure the integrity of the cladding avoiding the blistering phenomenon To avoid thermally induced fuel damage Fluid-Structure Interaction Wall temperature Safety Relevant Non-Safety Relevant Departure from Nucleate Boiling Flow Instability Phenomenon Onset of Nucleate Boiling

Design Criteria Relevant T-H Aspects in the Design of the RRR

Computational Tools Relevant T-H Aspects in the Design of the RRR Low Power State CAUDVAP - Hydraulic calculations TERMIC - TH calculations High Power State CONVEC - TH calculations Transients Analysis PARET - Reactivity Insertion Analysis RETRAN / RELAP - LOFA, LOCA, LOHS Analysis SteadyState

Closure flow Safety Features Relevant T-H Aspects in the Design of the RRR  Natural convection regime  Under-water core Shutdown the reactor Provide the adequate heat removal Contain radioactive materials Operational Features

Cooling in Natural Convection Relevant T-H Aspects in the Design of the RRR Inertia fly-wheel o Siphon-effect breaker redundancy q Water inlet for natural convection 2 in each PCS inlet pipe 2 different levels Normal Shutdown Loss of power supply incident 4 flap-valves

Under-water Core Relevant T-H Aspects in the Design of the RRR Zircalloy chimney surrounding the core Emergency Make-up Water System Maintains the core under water Assures an independent water reservoir Enhances natural convection Provides physical independence between the core and the pool Compensates evaporation and leaks

Pneumatic irradiation devices Cold Neutron Source Hot Neutron Source (future) Relevant Experimental Facilities Relevant T-H Aspects in the Design of the RRR Irradiation rigs 6 Silicon Doping 17 “Bulk” 12 Mo 3 I 2 Ir

Bulk Irradiation Facilities Safety Features Relevant T-H Aspects in the Design of the RRR  Cooling in natural convection regime Inertia fly-wheel 2 flap-valves Normal Shutdown Loss of power supply incident Siphon-effect breaker redundancy Water inlet for natural convection

Bulk Irradiation Facilities Safety Features Relevant T-H Aspects in the Design of the RRR Skirt Maintains the rig under water  Under-water Rigs Assures an independent water reservoir

Conclusions Relevant T-H Aspects in the Design of the RRR Use of commercial safety analysis codes Use of commercial safety analysis codes Capability to provide a T-H design that assures the safety and quality requirements of new generation RRs Capability to provide a T-H design that assures the safety and quality requirements of new generation RRs Use of emerging engineering tools Use of emerging engineering tools The T-H design of the RRR fulfils high standard safety features The T-H design of the RRR fulfils high standard safety features