Task 1 Progress: Analysis of TREAT Minimum Critical and M8CAL Cores with SERPENT and SERPENT/PARCS

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1 Task 1 Progress: Analysis of TREAT Minimum Critical and M8CAL Cores with SERPENT and SERPENT/PARCS Volkan Seker, Matt Neuman, Nicholas Kucinski, Hunter Smith, Tom Downar University of Michigan May 24,

2 Objectives To obtain a Monte Carlo core model that can be used as a reference for; Understanding the physics of the TREAT reactor. Parametrics and UQ analysis. Basis for cross section generation effort with SERPENT for Spatial Kinetics Code PARCS Steady-state analysis with PARCS/AGREE code system Basis for the IRPhEP Benchmarks of Minimum Critical Core and M8CAL 2

3 Minimum Critical Core 133 Standard Fuel Elements 8 Control Rod Fuel Elements 16 Zr-Cladded Dummy Fuel Element Control rods are above the upper reflector (completely out of the core) Specs from INL/EXT BATMAN report 3

4 Assemblies Used in the Minimum Critical Core Loading 4

5 Standard Fuel Assembly SERPENT Model SERPENT MODEL 5

6 Control Rod Fuel Assembly SERPENT Model SERPENT MODEL 6

7 Minimum Critical Core Serpent Model Al Reflector Liner Al Top Plate Permanent Reflector Axial View 7

8 Minimum Critical Core Serpent Model A A A-A Tie bolt Instrumentation hole Radial View 8

9 MCM Core Control Rod Positions Steel Cladded Graphite section (Poison Section) SS adapter Zr-2 Cladded Graphite follower section SS adapter 9

10 Principal Uncertainties with TREAT Minimum Critical Mass Core Loading Boron impurity in the graphite fuel Graphitization Core configuration Impurities in the reflector graphite Carbon capture (ENDF/B-7.0 vs. ENDF/B-7.1) 10

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17 Proposed Benchmark Specifications Boron impurity: 7.53ppm (±1.16)* Iron impurity: 267 ppm** Vanadium impurity: 30ppm** Uranium Content: 93.24%U-235, 5.43%U-238, 0.91% U %U-236** Graphitization: 59%** ENDF/B VII.1 library for the correction in the carbon capture in thermal range *H. Zhou study, 5/18/16 ** BATMAN, INL, Bess et al., Oct,

18 Specifications (cont.) Fuel cladding: Zircaloy-3, data from the GDMS measurements in BATMAN report were taken into account Reflector: CP-2 Graphite, data from the GDMS measurements in BATMAN report were taken into account Standard composition used for all the other materials used in the model. 18

19 Parametrics with the SERPENT MC Core Model Case k eff Diff (pcm) Base: 7.53ppm Boron 267ppm Fe 59%Graphitization ENDF/B Zr Assembly ±20pcm 5.9ppm Boron ±23pcm ppm Fe ±19pcm 218 0% Graphitization 100% Graphitization ±20pcm ±20pcm Zr Assembly ±21pcm

20 The M8 Power Calibration Experiment (M8CAL) Includes 23 irradiations to determine the relationship between the fission power generated in the TREAT core and the fission power in the test fuel. 318 Fuel assemblies (15 with thermocouples) 20 Control Rod assemblies (8 shutdown, 8 transient and 4 compensation) 12 Zr-Cladded reflector assemblies ( 1 of them is source) 8 slotted dummy assemblies 1 slotted half assembly and 1 Zrcladded half dummy assembly. 20

21 M8CAL Serpent Model A B A B 21

22 M8CAL Serpent Model Section A-A Section B-B 22

23 M8CAL SERPENT Results Case Base: 7.53ppm Boron 267ppm Fe 59%Graphitization ENDF/B 7.1 C/S Rod 22in CR Rod OUT TR Rod OUT k eff ±20pcm Reactivity (%) EXP SERPENT Rod Position (in) 23

24 Deterministic Codes: SERPENT/PARCS Lattice Code: SERPENT GENPMAXS Neutron Flux Solver: PARCS T/F: AGREE Cross Section Library (PMAX) 24

25 PARCS Modeling for TREAT: Single Assembly Benchmarking 12 sections in the fuel (10.19cm tall) - Generate cross sections for each axial region Vacuum axial boundary conditions Reflective radial boundary conditions Four reflector regions - Two graphite reflector (~60cm) - Two Zirconium spacer (~0.5cm) - 14 Group Xsec from SERPENT Orange = Fuel Yellow = Reflector Zirconium Spacer 25

26 PARCS: Single Assembly Power Shape Axial Power Profile Serpent k eff : ±7pcm Relative Power SERPENT PARCS PARCS_w_ADFs Axial Position Relative % Error PARCS without ZDF: PARCS with ZDF: ZDF m, g Het, g Hom, g 26

27 3D SERPENT/PARCS Model Homogenized Upper Reflector Region for PARCS Homogenized Radial and Lower Reflector Region 27

28 SERPENT/PARCS Preliminary Result for MCM Core 3D MCM PARCS Model 14G Cross Sections from: SERPENT 2D fuel assembly SERPENT 2D control rod assembly Reflector Cross Sections from 3D SERPENT single assembly Code k eff Diff (pcm) Serpent ±21pcm PARCS w/o ADF PARCS w ADF and Reflector ZDF

29 Ongoing Work Implementation of Eddington Factors and Directional Diffusion Coefficients in PARCS Finalize specification for the MCM and M8CAL benchmarks for IRPhEP Perform similar analysis of M8CAL w/ SERPENT/PARCS as performed with MCC Complete UQ/Sensitivity Analysis on MCC and M8CAL Perform V&V on the coupled PARCS/AGREE thermal-fluids model for TREAT steady-state and transient applications. 29