Monte-Carlo calculations in reactor design

1. Monte-Carlo calculations in reactor design G.B. Bruna FRAMATOME-ANP

2. Monte-Carlo calculations in reactor design • Samples : • HTR-10 Benchmark analysis, • Rhodium SPND detectors, • Mock-up experiments with void, • Others ....

3. HTR-10 Benchmark analysis • Benchmark problem definition • Sensitivity studies • Main Results

4. HTR-10 Benchmark analysis • Benchmark problem definition • 1) Cold (Temperature 300°K) • 2) U235 enrichment 3.3% à to 9.9% • 3) 31 or 33 element assemblies • 4) Two types of B4C burnable poisons • 5) 20 different mediums (colors) • 6) He core-cooling channels • 7) 150 fuel elements (30 columns, cylindrical core) • 90 fuel elements (18 columns, annular core) • 8) Four Benchmark configurations : • - 18 columns - 19 columns • - 24columns - 30 columns

5. HTR-10 Benchmark analysis • Heterogeneity levels • Coated micro-balls (first level)Compact (second level)Fuel assembly : 31 or 33 element compacts (third level)Axial superposition of 5 elements (forth level) • Radial core loading (fifth level)

6. HTR-10 Benchmark analysis 31-Element Assembly Compact/Element Burnable Poison

7. HTR-10 Benchmark analysis HTR-10 Benchmark analysis Hexagonal Compact

8. HTR-10 Benchmark analysis Hexagonal Lattice

9. HTR-10 Benchmark analysis Cubic Lattice

10. HTR-10 Benchmark analysis Radial Heterogeneity inside the Hexagonal Compact

11. HTR-10 Benchmark analysis Unclustered 18-Column Core

12. HTR-10 Benchmark analysis Unclustered 19-Column Core

13. HTR-10 Benchmark analysis Unclustered 24-Column Core

14. HTR-10 Benchmark analysis Unclustered 30-Column Core

15. HTR-10 Benchmark analysis 1/4 30-Column Unclustered Core

16. HTR-10 Benchmark analysis Clusters inside 30-Column Core

17. HTR-10 Benchmark analysis Clustered 30-Column Core

18. HTR-10 Benchmark analysis Adjusted Clustered 30-Column Core

19. HTR-10 Benchmark analysis • Sensitivity-studies(1 pcm = 1.E-5) • Graphite impurities > 5000 pcm (total) • Dummy assemblies ~3000 pcm • Helium channels ~2000 pcm • Bullets lattice arranged vs. random < 200 pcm • Compact heterogeneity < 200 pcm • First-level homogenization < 500 pcm • Second-level homogenization  10000 pcm • Data Libraries JEFF2 vs. ENDF-BVI ~500 pcm

20. HTR-10 Benchmark analysis • Configuration Experiment Calculation • 18 col. ann. core Sub-critical 0.99700 • 19 col. ann. core Over-critical 1.01300 • clustered 24 col. • ann. core 1.0000 1.00110 • clustered 30 col. • cylindrical core 1.0000 0.99980

21. HTR-10 Benchmark analysis • Core Average 5 Labs Japan(2), Holland, Russia, USA (ORNL) • 18 col. ann. core Keff 1.02150 • clustered 24 col. critical rod ins. 82 cm ann. core • clustered 30 col. • cylindrical core critical rod ins. 123 cm

22. Rhodium SPN Detectors • US-3D Device • Physics of Rhodium SPN Detectors • Monte-Carlo studies on : • heterogeneity • Rhodium burn-out

23. MOVABLE FLUX MAPPING SYSTEM ALARMS US-3D OPERATION AID SYSTEM CORE Rhodium SPN Detectors

24. Rhodium SPN Detectors Detectors n Generic detector (i, j, k)

25. Rhodium SPN Detectors Real Geometry (Sec. R-R) Axial heterogeneity Radial heterogeneity APOLLO MCNP Geometry Representation in APOLLO

26. Rhodium SPN Detectors Self-shielding effect

27. 5000 b 10 Mev Gr. 1 0.907 Mev Gr. 6 Gr. 5 Gr. 4 Gr. 3 Gr.2 7.466 Kev 0.134 ev 0.625 ev 4.129 ev Rhodium SPN Detectors The Rh microscopic absorption cross-section

28. Rhodium SPN Detectors Rh reaction rates

29. Rhodium SPN Detectors Rh reaction rates

30. RR per annular region 50.4% 28.4% 21.3% Rhodium SPN Detectors Rh reaction rates

31. Rhodium SPN Detectors Rh reaction rates

32. Mock-up experiments with void • Physical analysis of heterogeneous void • Monte-Carlo calculations of mock-up experiments: • EPICURE • ERASME • Others

33. Void of mock-up experiments IAEA Benchmark Sample Geometry Homogeneous Void Infinite Medium Heterogeneous Void Cluster

34. Mock-up experiments with void Homogeneous Void Infinite Medium Heterogeneous Void Cluster

35. Mock-up experiments with void UO2 MOX

36. Mock-up experiments with void • Cluster of 9 {10*10 pin} assemblies in Inf. Med. (pitch 1.26 cm), with a central MOX assembly with Pu enrichment: • HMOX 14.40 • MMOX 9.70 • LMOX 5.40 • (UO2 3.35)

37. Mock-up experiments with void

38. Mock-up experiments with void • In thewet MMOX cluster, typical values of Kinf* and Imp* are the following: • Zone Imp* Kinf* • UO20.88 1.3697 • MOX 0.12 1.1447 • Whole Cluster 1.3427 • *Rouded off values

39. Mock-up experiments with void • In the MMOX clusterwith central void,typical values of Kinf*and Imp* are the following: • Zone Imp* Kinf* • UO21.3697 0.96 • MOX0.7738 0.04 • Whole Cluster1.3458 • *Rounded off values

40. Mock-up experiments with void Wet MOX Dry XS Flux

41. Mock-up experiments with void UOX-UOX EPICURE Dried zone 3.7% UOX

42. Low and High Enrich. UOX-MOX EPICURE MOX 3.7% UOX

43. Mock-up experiments with void (Low Enrich. UOX-UOX EPICURE)

44. Mock-up experiments with void (UOX-MOX EPICURE)

45. Mock-up experiments with void (ERASME Series Experiments)

46. Mock-up experiments with void (Synopsis of All Experiments)

47. Mock-up experiments with void (Low Enrich. EPICURE with bubble)

48. Mock-up experiments with void (High Enrich. EPICURE with bubble)

49. Mock-up experiments with void • Discrepancies on reactivity are lower than 100 pcm on the average of 35 experiments, without any significant trend; • No biases have been observed between JEF-2.2 and ENDFB-VI libraries, except for very hard spectra where ENDFB-VI overestimates reactivity up to 1000 pcm.

50. Others ... • Other Monte-Carlo studies : • Criticality, • Sub-critical approach to divergence, • Fluence and vessel life-time.