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 Benchmark problem definition Sensitivity studies Main Results HTR-10 Benchmark analysis

4 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 HTR-10 Benchmark analysis

5 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) HTR-10 Benchmark analysis

6 Compact/Element Burnable Poison 31-Element Assembly

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

8 Hexagonal Lattice HTR-10 Benchmark analysis

9 Cubic Lattice HTR-10 Benchmark analysis

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

11 Unclustered 18-Column Core HTR-10 Benchmark analysis

12 Unclustered 19-Column Core HTR-10 Benchmark analysis

13 Unclustered 24-Column Core HTR-10 Benchmark analysis

14 Unclustered 30-Column Core HTR-10 Benchmark analysis

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

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

17 Clustered 30-Column Core HTR-10 Benchmark analysis

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

19 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  pcm Data Libraries JEFF2 vs. ENDF-BVI ~500 pcm HTR-10 Benchmark analysis

20 ConfigurationExperiment Calculation 18 col. ann. coreSub-critical col. ann. coreOver-critical clustered 24 col. ann. core clustered 30 col. cylindrical core HTR-10 Benchmark analysis

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

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

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

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

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

26 Self-shielding effect Rhodium SPN Detectors

ev0.625 ev4.129 ev 5000 b Gr. 6Gr. 5Gr. 4Gr Kev Gr.2 Gr Mev 10 Mev The Rh microscopic absorption cross-section Rhodium SPN Detectors

28 Rh reaction rates Rhodium SPN Detectors

29 Rhodium SPN Detectors Rh reaction rates

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

31 Rhodium SPN Detectors Rh reaction rates

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

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

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

35 UO2 MOX Mock-up experiments with void

36 Cluster of 9 {10*10 pin} assemblies in Inf. Med. (pitch 1.26 cm), with a central MOX assembly with Pu enrichment: –HMOX14.40 –MMOX 9.70 –LMOX 5.40 –(UO2 3.35) Mock-up experiments with void

37 Mock-up experiments with void

38 In the wet MMOX cluster, typical values of Kinf* and Imp* are the following: ZoneImp*Kinf* UO MOX Whole Cluster –*Rouded off values Mock-up experiments with void

39 In the MMOX cluster with central void, typical values of Kinf*and Imp* are the following: ZoneImp* Kinf* UO MOX Whole Cluster –* Rounded off values Mock-up experiments with void

40 WetMOX XS Flux Dry Mock-up experiments with void

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

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

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

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

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

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

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

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

49 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. Mock-up experiments with void

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