Relevant Thermal-Hydraulic Aspects in the Design of the RRR

1. Relevant Thermal-Hydraulic Aspects in the Design of the RRR A. Doval, C. Mazufri F.P. Moreno 10898400- Bariloche, Rio Negro, Argentina

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

17. Relevant T-H Aspects in the Design of the RRR Bulk Irradiation FacilitiesSafety Features • Under-water Rigs Skirt Assures an independent water reservoir Maintains the rig under water

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