NRAD - ANS 2012

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Additional Benchmark Evaluation of the NRAD Reactor LEU Core Conversion

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NRAD - ANS 2012

  1. 1. Additional Benchmark Evaluation ofthe NRAD Reactor LEU CoreConversionJohn D. BessMargaret A. MarshallIdaho National Laboratory 2012 ANS Annual Meeting Chicago, Illinois June 24-28, 2012 This paper was prepared at Idaho National Laboratory for the U.S.Department of Energy under Contract Number (DE-AC07-05ID14517)
  2. 2. Neutron Radiography (NRAD) Reactor 250 kW TRIGA Mark II Linear channel Safety channel 2 Conversion-type North beam tube Located at INL G North beam aperture N  Former PRNC 2-MW reactor I H Empty grid J 60 U(30/20)ErZrH rods location Graphite  Formerly HEU FLIP fuel A reflector assembly 12 graphite reflectors B C East 3 control rods D beam tube 2 neutron radiography E East beam beam lines F aperture Empty positions for in- L 1 2 3 4 5 6 core experimentation K N  Part of Hot Fuels M Safety channel 1 Log channel Examination Facility (HFEF) NW NE Control rod SW SE Fuel cluster assembly Neutron source (AmBe) Standard fuel element Irradiation positions 10-GA50002-04-3 2
  3. 3. TRIGA Fuel Conversion HEU LEU Nominal (FLIP) (30/20) Design Data Core Configuration Operational Fuel Fuel Number of Fuel Elements 60Number of Fuel Rods 60 60 Total Mass (g) 2506.5 ± 3.4 Uranium Mass (g) 749.9 ± 2.7Fuel Type UErZrH UErZrH 235U Mass (g) 148.0 ± 0.6Uranium Enrichment % 70 19.75 235U Enrichment (%) 19.74 ± 0.02Uranium Density wt-% 8.42 30 U Mass Content (wt.%) 29.92 ± 0.09Erbium wt-% 1.48 0.90 H/Zr Ratio 1.58 ± 0.01Zirconium Rod OD, mm 5.715 5.715 Er Content (wt.%) 0.90 ± 0.02 C Content (wt.%) 0.30 ± 0.02Fuel Meat OD, mm 34.823 34.823 Fuel Element Length (mm) 380.2 ± 0.4Fuel Meat L, mm 381 381 Fuel Element Diameter (mm) 34.805 ± 0.003Clad Thickness, mm 0.508 0.508 Cladding Inner Diameter (mm) 34.894 ± 0.005Clad Material 304 SS 304 SS Fuel-Clad Difference (mm) 0.089 ± 0.005 3
  4. 4. Current Benchmark: NRAD-FUND-RESR-001 60-fuel-rod critical configuration completed Available in March 2011 edition of IRPhEP Handbook http://irphep.inl.gov/ irphep@inl.gov Also available in Sept. 2011 edition of ICSBEP Handbook  Useful for storage, handling, and transportation of UZrH 4
  5. 5. International Handbook of Evaluated ReactorPhysics Benchmark ExperimentsMarch 2012 Edition 16 Contributing Countries Data from 56 Experimental Series performed at 32 Reactor Facilities Data from 52 out of the 56 series are published as approved benchmarks Data from 4 out of the 56 series are published in DRAFT form 5
  6. 6. Summary of the Benchmark Process 6
  7. 7. NRAD LEU TRIGA Start-Up Tests March 9 – June 7, 2010  Calorimetric power calibrations Fuel loading approach  100, 200, 250 kW to critical  Full power operation Initial critical  ER  56 fuel rods  Graphite reflector  Rod worths, ER, SDM movements Operational core  Dry tube worth  60 fuel rods  Radiography beam  Critical, rod worths, ER, characterization SDM performed after start- up tests were completed 7
  8. 8. Simplified Benchmark Model – 60 Rods 23.095 Fully 56 Rods inserted control rod Water North beam tube (void) 1.905 13.97 Fully withdrawn control rod S2 East beam 38.1 16.51 tube (void) Fuel 13.97 C L midplane Graphite108.73751 65.72251 Fuel Beam reflector rod filter tube S1 block R D 90 0.123825 5.08 Water Fuel rod S1 Shim 1 control rod 19.92 S2 Shim 2 control rod R Regulating control rod Dimensions in cm Graphite reflector block 10-GA50002-145-6 Dimensions in cm 10-GA50002-145-9 8
  9. 9. Update to Current Benchmark Model Fuel batch data  Zr data from Y-12, from CERCA CERCA, and EAG Updated 234U, 236U, measurements and EBC in fuel Significant Negligible reduction in Hf computational bias content in model 50% Reduction in o +0.1 %Δkeff associated 100% reduction in uncertainties Hf uncertainty 9
  10. 10. Highlights of Benchmark Evaluation Water Saturation of  Computational Bias of Graphite Blocks ~1%  Other TRIGAs with same Largest Single problem Uncertainty o Musashi Mark II (100 kW) – MCNP+ENDF/B-V ±0.0025 Dk (56 rods) o Slovenia Mark II (250 kW) – MCNP+ENDF/B-VII ±0.0021 Dk (60 rods)  Bias variation o Quantity of fuel o Cross Section Data Total Experimental o Monte Carlo Code – KENO vs MCNP Uncertainty  Bias increases with ±0.0028 Dk (56 rods) core size ±0.0024 Dk (60 rods)  ~5¢ per fuel rod 10
  11. 11. Effect of Graphite Water Saturation60-Fuel-Element Core 11
  12. 12. Criticality Results – 56 Rods Experiment keff + Simplification Bias = Benchmark keff 1.0000 + 0.0014 = 1.0014 ± 0.0029 (±$0.39)Analysis Calculated Bias Neutron Library Code keff ± σ Worth ($) ENDF/B-VII.0 1.00906 ± 0.00007 0.76 1.02 JEFF-3.1 1.00712 ± 0.00007 0.57 0.76MCNP5 JENDL-3.3 1.00616 ± 0.00007 0.48 0.63 ENDF/B-VI.8 1.00437 ± 0.00007 0.30 0.40 ENDF/B-VII.0 1.00901 ± 0.00007 0.76 1.01 (238-group)KENO-VI ENDF/B-VII.0* 1.00898 ± 0.00008 0.76 1.01 (continuous energy)SERPENT ENDF/B-VII.0 1.00912 ± 0.00008 0.77 1.03 12
  13. 13. Criticality Results – 60 Rods Experiment keff + Simplification Bias = Benchmark keff 1.0000 + 0.0010 = 1.0010 ± 0.0025 (±$0.34)Analysis Calculated Bias Neutron Library Code keff ± σ Worth ($) ENDF/B-VII.0 1.01029 ± 0.00007 0.93 1.24 JEFF-3.1 1.00822 ± 0.00007 0.72 0.96MCNP5 JENDL-3.3 1.00731 ± 0.00007 0.63 0.84 ENDF/B-VI.8 1.00558 ± 0.00007 0.46 0.61 ENDF/B-VII.0 1.01041 ± 0.00007 0.94 1.25 (238-group)KENO-VI ENDF/B-VII.0* 1.00933 ± 0.00008 0.83 1.11 (continuous energy)SERPENT ENDF/B-VII.0 1.01032 ± 0.00008 0.93 1.24 13
  14. 14. Reactivity Effects Measurements Rod measurements  Shim rods  Uncertainty ~10%  Rod drop o Technique (6%)  Reg rod o Shadowing (8%)  Rod drop and positive period o Statistical Error (0.2%)  SDM βeff  Rod drop sum  NRAD = 0.0071  ER  GA = 0.0078  Positive period  Range = 0.007-0.008  Graphite blocks  Benchmark =  Compare recalibrated ER difference 0.0075 ± 5% (1σ)  Dry tube  Compare ER difference 14
  15. 15. Location of Dry Tube and Graphite Blocks North beam A5 tube (void) C1 13.97 S2 East beam tube (void) 13.97 S1 R D1 Dry tube (void) D 90 Water Fuel element S1 Shim 1 control rod S2 Shim 2 control rod R Regulating control rod Dimensions in cm Graphite reflector block F4 11-GA50002-31-6 15
  16. 16. Reactivity Effects Results – 56 RodsWorth Measurement Benchmark ($) MCNP5 ($) C/E Excess Reactivity 0.37 ± 0.02 0.43 ± 0.02 1.16 ± 0.10 Shutdown Margin -7.54 ± 0.49 -7.83 ± 0.23 1.04 ± 0.07 Shim Rod 1 -2.76 ± 0.31 -3.04 ± 0.15 1.10 ± 0.14 Shim Rod 2 -2.72 ± 0.30 -2.60 ± 0.13 0.96 ± 0.12 Reg Rod -2.43 ± 0.23 -2.62 ± 0.11 1.08 ± 0.10 16
  17. 17. Reactivity Effects Results – 60 RodsWorth Measurement Benchmark ($) MCNP5 ($) C/E Graphite Block A5 -0.17 ± 0.06 -0.13 ± 0.06 0.79 ± 0.45 Graphite Block C1 -0.41 ± 0.06 -0.39 ± 0.04 0.96 ± 0.18 Graphite Block D1 -0.43 ± 0.06 -0.41 ± 0.04 0.95 ± 0.17 Graphite Block F4 -0.45 ± 0.06 -0.44 ± 0.04 0.98 ± 0.17 Excess Reactivity 1.12 ± 0.05 1.17 ± 0.04 1.05 ± 0.06 Shutdown Margin -6.73 ± 0.47 -6.66 ± 0.23 0.99 ± 0.08 Shim Rod 1 -2.68 ± 0.30 -2.79 ± 0.14 1.04 ± 0.13 Shim Rod 2 -2.75 ± 0.33 -2.63 ± 0.13 0.95 ± 0.12 Reg Rod -2.42 ± 0.16 -2.42 ± 0.08 1.00 ± 0.07 Dry Tube -0.06 ± 0.01 -0.04 ± 0.01 0.69 ± 0.25 17
  18. 18. Future Work NRAD Upgrade 4 additional fuel North beam tube rods (void) 13.97 4 graphite rods D 90 Repeat start-up tests at 62 and 64 S2 East beam rod loadings tube (void) 13.97 Weigh graphite S1 R blocks Flux measurements Void effects Water Graphite element Characterize beams Fuel element S1 Shim 1 control rod S2 Shim 2 control rod R Regulating control rod Dimensions in cm Graphite reflector block 11-GA50002-31-3 18
  19. 19. Conclusion Completed benchmark evaluation of cold start-up measurements  Large uncertainty in water saturation of graphite blocks  ~1% high computational bias in criticality  Very good agreement for worth measurements  Path forward for additional benchmark experiment data 19
  20. 20. ¿Questions? 20
  21. 21. Extra Slides 21
  22. 22. Experiment Evaluation – Biases Simplifications were  Noticeable biases needed Simplification of  Understand worth fuel rod end fittings and sensitivity of Removal of steel various components impurities  Develop easier to use Use of average fuel benchmark model composition  Speed up calculation Replace control rod time guide tubes with H2O Most simplifications caused minor Replace beam line structure with void changes in keff 22
  23. 23. Calculated Spectral Data – 56 rods (MCNP5) Model Detailed Simple Cross Section Library ENDF/B-VII.0 ENDF/B-VII.0 keff 1.00765 1.00906 ±σk 0.00007 0.00007 Neutron Leakage (%) 0.03 2.28 Thermal (<0.625 eV) 80.58 80.75 Fission Fraction, Intermediate 16.42 16.27 by Energy (%) Fast (>100 keV) 2.99 2.98 234U 0.01 0.01 235U 98.74 98.74 Fission Fraction, 236U 0.01 0.01 by Isotope (%) 238U 1.24 1.23 Average Number of Neutrons Produced 2.444 2.444 per Fission Energy of Average Neutron Lethargy 0.26679 0.26275 Causing Fission (eV) 23
  24. 24. Calculated Spectral Data – 60 rods (MCNP5) Model Detailed Simple Cross Section Library ENDF/B-VII.0 ENDF/B-VII.0 keff 1.00934 1.01029 ±σk 0.00007 0.00007 Neutron Leakage (%) 0.04 2.39 Thermal (<0.625 eV) 80.38 80.54 Fission Fraction, Intermediate 16.60 16.46 by Energy (%) Fast (>100 keV) 3.02 3.00 234U 0.01 0.01 235U 98.73 98.73 Fission Fraction, 236U 0.01 0.01 by Isotope (%) 238U 1.25 1.24 Average Number of Neutrons Produced 2.444 2.444 per Fission Energy of Average Neutron Lethargy 0.27191 0.26810 Causing Fission (eV) 24
  25. 25. Discussion of Cross Section Data Cause of Bias?  Er  Cross section and/or code  KENO and MCNP keff related values agree when Er is  Fuel rods significant removed 235U and 238U  Low-lying resonance approximations in free-  Small difference between gas scattering kernels ? JENDL-3.3 and ENDF/B- VII.0 data  Currently being o JENDL thought to be “more investigated correct” o KUCA 91Zr and ZrH S(a,b)  Graphite (Cnat)  Bias identified  (n,g) larger in JENDL-3.3 o Slovenia TRIGA Mark II than ENDF/B-VII.0 o Fuel contains no Er  (n,g) increased further o ICNC 2011 (Sept.) in JENDL-4.0 base on  ZrH S(a,b) calculated HTGR research differently in JEFF-3.1 and ENDF/B-VII.0 25
  26. 26. Future Work – II Computational  Additional “To-Do” Methods Benchmarks Continue to SNAP 10A/2 water immersion investigate Er experiments o KUCA experiments Expand NRAD Investigate thermal benchmark library scattering S(α,β) Invite other cross sections members of TRIGA o Collaborative effort community to benchmark their reactors 26
  27. 27. References Bess, J. D., Maddock, T. L., Marshall, M. A., “Fresh Core Reload of the Neutron Radiography (NRAD) Reactor with Uranium(20)-Erbium- Zirconium-Hydride Fuel,” INL/EXT-10-19486, Idaho National Laboratory (2010). International Handbook of Evaluated Reactor Physics Benchmark Experiments, NEA/NSC/DOC(2006)1, OECD-NEA, Paris, France (2011). Matsumoto, T., Hayakawa, N., “Benchmark Analysis of TRIGA Mark II Reactivity Experiment Using a Continuous Energy Monte Carlo Code MCNP,” J. Nucl. Sci. Tech., 37(12), 1082-1087 (2000). Snoj, L., Žerovnik, G., Trkov, A., “Analysis of Cross Section Libraries on Zirconium Benchmarks,” Proc. ICNC 2011, Edinburgh, Scotland, September 19-22 (2011). Jeraj, R., Ravnik, M., “TRIGA Mark II Reactor: U(20)-Zirconium Hydride Fuel Rods in Water with Graphite Reflector,” IEU-COMP-THERM-003, International Handbook of Evaluated Criticality Safety Benchmark Experiments, NEA/NSC/DOC(95)03, OECD-NEA, Paris, France (2010). Shimakawa, S., Goto, M., Nakagawa, S., Tachibana, Y., “Impact of Capture Cross-Section of Carbon on Nuclear Design for HTGRs,” Proc. HTR 2010, Prague, Czech Republic, October 18-20 (2010). 27
  28. 28. Detailed Model Development 28
  29. 29. Fuel Clusters Top Assembly 7.7089 Fuel Rods 3.8862 3.8862 Top View 8.10006 Bottom Dimensions in cm Assembly 10-GA50002-145-5 10-GA50002-74-2 Dimensions in cm 10-GA50002-145-4 29
  30. 30. Top fuel fittingFuel Rods Top end fitting (SS 304/304L) OD 3.4894 cm Cladding 0.180 MIN. 1.27 Void gap 0.724535 Upper Top axial reflector (graphite) 8.6868 fuel reflector OD 3.27914 Cladding (SS 304/304L) ID 3.4894, OD 3.591 Zirconium rod U-Er-Zr-H fuel ID 0.635, OD 3.4805 23.125 (REF) 38.02 58.73751 + 0.000 25.875 - 0.031 Fuel pellets (3) Zirconium rod OD 0.5715 Molybdenum poison disc + 0.003 1.370 - 0.000 I.D. (REF) 0.079375 Molybdenum poison disc Lower fuel OD 3.46964 reflector Bottom axial reflector (graphite) OD 3.27914 8.6868Bottom end fitting (SS 304/304L) OD 3.4894 1.27 Dimensions in cm Bottom fuel fitting 10-GA50002-145-1 1.414 DIA. Dimensions in inches NOM. (REF) 10-GA50002-76 30
  31. 31. Control Rods Detail of top fitting 2.5 1.25 0.5 Top end fitting (Al 6061) 5/8 flats 0.5 0.625 OD 3.03276 1.9685 0.40 D 1.194 D 1/2-13 UNC-2A 0.125 + 0.000 0.060 - 0.004 0.1875 Void Void 17.78 Cladding (Al 6061) ID 3.03276 1-1/8" O.D. x 0.035" wall OD 3.175 L 6.5 Al alloy tube Spacer 1.187 +0.005 O. D. - 0.000 0.5 D thru L 0.5 59.436 24.00 REF 23.40 B4C absorber 23.25 1-1/4" O.D. x 0.028" wall OD 3.01498 L 23.4 Al alloy tube 38.1 15.0 Boron carbide D 1.187 +0.030 - 0.000 Detail of bottom fitting D 1.194 0.75 Bottom end fitting (Al 6061) 0.625 OD 3.03276 0.1875 1/16 x 1/16 groove 1.5874 Dimensions in cm 10-GA50002-145-2 0.060 +0.000 0.125 1/16 DIA -0.004 THRU Dimensions in inches 10-GA50002-90 31
  32. 32. Guide Tube 32
  33. 33. Graphite Reflectors Handle W0170-0089-DE (REF) Screw, HEX SOC HD 5/8-11 UNC-2A x 2 LG ALUM 2011-T3 2 REQD Graphite element reactor grade 0.9525 cm x 45° chamfer 25.875 ± 0.125 65.72251 7.366 7.366 Top View 0.656 +0.002 DIA DRILL - 0.005 x 0.875 ± 0.060 DP 2 places 5/8-11 UNC-2A THD Dowel pin Both ends 0.645 DIA x 1-1/2 LG Alum 2011-T3, 2 REQD Tie rod + 0.000 D 1.968 - 0.030 5/8 x 7-7/8 LG ALUM 2011-T3 Adapter ALUM 2011-T3 Dimensions in cm Adapter 10-GA50002-145-3 W0170-0090-DD (REF) 0.375 ± 0.030 x 45° ± 5° Hex nut Chamfer TYP 5/8-11 UNC-2B THD ALUM 2011-T3 2.900 +0.100 - 0.000 square Dimensions in inches 10-GA50002-05-1 33
  34. 34. Photograph of NRAD Tank 34

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