14           2        3Effect of Burn-up and HighBurn-up Structure on UO2Spent Fuel Matrix DissolutionD. Serrano-Purroy1, ...
This work is a part of a CollaborationAgreement between ITU/JRC-ENRESA-CTM/UPC to obtain the scientific dataneeded to bett...
SPENT FUEL DISSOLUTION                                                                                -2                  ...
PREVIOUS UO2-MATRIX DISSOLUTION RATES•   Dynamic experiments                           -9.00•   Air conditions•   Powder  ...
High Burn-up Structure (HBS)Increasing burn-ups, neutron capture of U-238 produces Pu-239 generatingan external layer with...
RIM THICKNESS                     110                     100                      90                                     ...
RN release from Spent Fuel                                                Grain boundaries:                               ...
Objective Study the leaching behavior of High Burn-up  PWR fuels (48 and 60 Mw d/kgU) with  special emphasis on the HBS r...
Spent fuel samples           Burn-up           48            60          (MW d/kgU)        (MBU) PWR   (HBU) PWR MBU      ...
Spent fuel sample preparation   Two different samples were prepared from a different radial position in order to study the...
Spent fuel sample preparation    HBU: Core (left) and OUT (right) sample after drilling and detachment
Spent fuel sample preparation SEM characterisation of core sample a) before cleaning b) after cleaning at 1000 magnificati...
Spent fuel sample characterization    Fuel     Parameter            Core             OUT            Mean particle         ...
Spent fuel sample characterization The percentage of the surface broke through trans-  granular process in the Core sampl...
Experimental Setup
Experimental Setup installed inside Hot Cell
Inventory for CORE, OUT (μg of element/g of SNF)                              Element    60BU-CORE         60BU-OUT       ...
Experimental conditions   •NaHCO3          10-3 mol·dm-3   •NaCl            1.9·10-2 mol·dm-3   •In air          PO2 21%  ...
Dissolution Rates:                     Q Ci          rate i                      ARadionuclide rates normalized to uranium...
60HBU Dissolution & normalized rates for Actinides                                                                CORE    ...
48 MBU Dissolution & normalized rates for Actinides                                                                  CORE ...
Results               CORE        OUT         CORE        OUT              60HBU       60HBU       48MBU       48MBUNORMAL...
Some remarks   Uranium and Actinide dissolution rates are twice    faster in the CORE region than in the Periphery   Exc...
60HBU Normalized Rates for Fission Products                                                                 CORE          ...
48MBU Normalized Rates for Fission Products                                                                         CORE  ...
Results Ratio     CORE    OUT     CORE    OUT          60HBU   60HBU   48MBU   48MBU Rb/U      25.4   113.7    11.0    4.0...
Results: FP rates/ U rate                          120,00                          100,00                           80,00 ...
Some remarks   Fission products normalized dissolution rates are    similar in 48MBU for both core and out samples   Fis...
Matrix dissolution rate comparison            -9.00                        Gray_33 MW d/kgU           Röllin_43 MW d/kg U ...
Conclusions                                                             -phase       Dissolution lowerUO2-matrix dissoluti...
THANK YOU FOR YOUR ATTENTION    GRACIAS POR SU ATENCIÓNAnd thanks to Argentina for sendingthis guy to Barcelona     Que bu...
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Effect of Burn-up and High Burn-up Structure on UO2 Spent Fuel Matrix Dissolution

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Effect of Burn-up and High Burn-up Structure on UO2 Spent Fuel Matrix Dissolution

  1. 1. 14 2 3Effect of Burn-up and HighBurn-up Structure on UO2Spent Fuel Matrix DissolutionD. Serrano-Purroy1, I. Casas2, E. González-Robles3,J. P. Glatz1, D. Wegen1, F. Clarens3, J. Giménez2,J. de Pablo2,3, A. Martínez-Esparza4 MRS’11, BUENOS AIRES, OCTOBER 2-6, 2011
  2. 2. This work is a part of a CollaborationAgreement between ITU/JRC-ENRESA-CTM/UPC to obtain the scientific dataneeded to better understanding thebehaviour of High Burn-up Spent Fuels
  3. 3. SPENT FUEL DISSOLUTION -2 log Fractional Release Rate (d-1) -3 -4 -5 grain boundaries UO2-matrix Rod Actínides & FP -6 14C (~ 98 %)Gap matrix14C; 129I;135Cs; 137Cs; -779Se; 99Tc;90Sr gap Cracks -8 Grain Boundary 14C; 129I; 0 1 2 3 4 5 6 7 Bubbles 135Cs; 137Cs; 79Se; 99Tc; 90Sr log time (y) L.H. Johnson, D.W. Shoesmith, “Radioactive Waste Forms for the future“, W. Lutze and R.C. Ewing, Eds., 1988
  4. 4. PREVIOUS UO2-MATRIX DISSOLUTION RATES• Dynamic experiments -9.00• Air conditions• Powder -9.50 Gray_33 MW d/ kgU• Fragment• Segment (Fuel+Cladding) Serrano_53 MW d/ kg U -10.00 log r (mol/m2·s) Röllin_43 MW d/ kgU -10.50 Gray_28 MW d/ kgU (0.01 M HCl/DIW) Gray_43 MW d/ kgU (0.01M HCl/DIW) -11.00 Serrano_53 MW d/ kgU_segment Serrano_29 MW d/ kg U_segment -11.50 Jegou_60 MW d/kg U_segment -12.00 -6 -5 -4 -3 -2 -1 log [HCO3-]
  5. 5. High Burn-up Structure (HBS)Increasing burn-ups, neutron capture of U-238 produces Pu-239 generatingan external layer with a higher burn-up (BU), increased porosity and fuelgrain subdivision resulting on the formation of the so-called HBS. The widthof this layer, observed for BU’s higher than 40 MW d/kgU, increases withthe BU and depends on the irradiation history. Intermediate zone HBS HBS particle CORE particle
  6. 6. RIM THICKNESS 110 100 90 Rt = 5.44BUR – 281Rim BU (MW/ d kgU) 80 70 60 50 40 30 20 20 30 40 50 60 70 80 Average BU (MW/d kgU) Johnson L., Ferry C., Poinssot C., Lovera P. Estimates of the Instant Release Fraction for UO2 and MOX Fuel at t=0. NAGRA-TR-04-08, 2004
  7. 7. RN release from Spent Fuel Grain boundaries: C, I, S, Cs, Se, Tc Grains: Gap region : (U,An,Ln)O 2 C, I, Cs, Se, Tc Oxide precipitates: Rb, Cs, Ba, Zr, Nb, Mo, Tc ?-particles/ metallic precipitates Mo, Ru, Pd, Tc, Rh 20kV x 1.500 µm 030996 10 (Ag, Cd, In, Sn, Sb) Cracks Fission Gas bubbles: RIM or HBS: Xe, Kr, I enriched in Pu Pellet gap Cladding : C
  8. 8. Objective Study the leaching behavior of High Burn-up PWR fuels (48 and 60 Mw d/kgU) with special emphasis on the HBS region related to UO2-matrix dissolution
  9. 9. Spent fuel samples Burn-up 48 60 (MW d/kgU) (MBU) PWR (HBU) PWR MBU Irradiation cycles 3 5 End of radiation 2000 2001 RIM (µm) 76 µm 155 µm calculatedHBU
  10. 10. Spent fuel sample preparation Two different samples were prepared from a different radial position in order to study the effect of HBS region 1. Cut pin into segments 2. Drill Core sample 3. Separation from claddingRIM widthOUT sample OUT sample 4. Sieving (50-100 µm) 5. Removing fines
  11. 11. Spent fuel sample preparation HBU: Core (left) and OUT (right) sample after drilling and detachment
  12. 12. Spent fuel sample preparation SEM characterisation of core sample a) before cleaning b) after cleaning at 1000 magnification (Scale: 30 µm)
  13. 13. Spent fuel sample characterization Fuel Parameter Core OUT Mean particle 68 ± 15 82 ± 8 size (μm) 60BU Specific surface 0.027 ± 0.007 0.022 ± 0.002 area (m2/g) Mean particle A: 45 ± 15 90 ± 40 size (μm) B: 140 ± 50 48BU Specific surface A: 0.04 ± 0.01 0.020 ± 0.009 area (m2/g) B: 0.013 ± 0.009
  14. 14. Spent fuel sample characterization The percentage of the surface broke through trans- granular process in the Core sample was 98 % for 48MBU fuel and 97% for 60HBU fuel. Therefore, only about 3% of the particle surface was estimated to contain open grain-boundaries in both fuels. The percentage of HBS particles present in OUT samples for 48MBU and 60HBU fuels determined by direct counting from SEM images is 5 and 19 respectively, these values change to 19 and 40 if geometry is taking into account.
  15. 15. Experimental Setup
  16. 16. Experimental Setup installed inside Hot Cell
  17. 17. Inventory for CORE, OUT (μg of element/g of SNF) Element 60BU-CORE 60BU-OUT 48BU-CORE 48BU-OUT Rb 500 ± 10 600 ± 100 320 ± 20 490 ± 20 Sr 800 ± 40 800 ± 100 730 ± 100 700 ± 20 Y 650 ± 10 770 ± 30 540 ± 10 660 ± 30 Inventory of each fraction Zr 6300 ± 200 7900 ± 700 3800 ± 300 4500 ± 200 experimentally Mo 5900 ± 300 8000 ± 400 3600 ± 200 4500 ± 200 Tc 1300 ± 100 1600 ± 50 840 ± 30 1090 ± 30 determined by dissolution Ru 4400 ± 200 5300 ± 600 2400 ± 100 3200 ± 200 in acidic media and Rh 650 ± 20 800 ± 100 510 ± 20 700 ± 100 further HR-ICP-MS and Cs 3800 ± 200 4800 ± 400 2600 ± 200 4200 ± 100 Ba 3300 ± 400 4300 ± 500 1800 ± 400 2000 ± 300 γ-spectroscopy analysis La 2000 ± 400 2300 ± 300 2700 ± 1000 2800 ± 500 Ce 4100 ± 500 4500 ± 800 3000 ± 700 3000 ± 400 Pr 1800 ± 200 2100 ± 300 1300 ± 200 1100 ± 200 Nd 7000 ± 1000 8000 ± 900 4900 ± 1300 4000 ± 600 Sm 1270 ± 100 1500 ± 100 1000 ± 200 800 ± 100 Eu 190 ± 10 200 ± 20 130 ± 10 130 ± 10 Gd 620 ± 20 800 ± 200 340 ± 40 300 ± 30 U 780000 ± 10000 770000 ± 60000 790000 ± 10000 780000 ± 10000 Np 810 ± 80 760 ± 80 900 ± 100 750 ± 20 Pu 8000 ± 540 11000 ± 1600 10400 ± 600 15200 ± 400 Am 840 ± 100 1200 ± 100 500 ± 30 800 ± 30 Cm 290 ± 40 460 ± 50 70 ± 10 110 ± 10
  18. 18. Experimental conditions •NaHCO3 10-3 mol·dm-3 •NaCl 1.9·10-2 mol·dm-3 •In air PO2 21% •Temperature 25 ± 5 ºC •pHi 8.0 ± 0.2 •pHo 7.2 ± 0.5 •Flow rate 0.025-0.1 L/min •Weight of solid 1g
  19. 19. Dissolution Rates: Q Ci rate i ARadionuclide rates normalized to uranium: massU Mi normalized ratei ratei massi MU
  20. 20. 60HBU Dissolution & normalized rates for Actinides CORE CORE 1,E-07 1,E-08 1,E-08 1,E-09 1,E-09 norm. rates (mol/m 2. s) 1,E-10rates (mol/m 2. s) 1,E-11 1,E-10 1,E-12 1,E-13 1,E-11 1,E-14 1,E-15 1,E-12 1,E-16 1,E-17 1,E-13 0 50 100 150 200 250 300 350 400 450 500 0 50 100 150 200 250 300 350 400 450 500 time (d) time (d) U Np Pu Am Cm U Np Pu Am Cm OUT OUT 1,E-07 1,E-08 1,E-09 1,E-08 rates (mol/m 2.s) 1,E-10 norm. rates (mol/m s) 2. 1,E-11 1,E-09 1,E-12 1,E-10 1,E-13 1,E-14 1,E-11 1,E-15 1,E-16 1,E-12 0 100 200 300 400 500 1,E-13 tim e (d) 0 100 200 300 400 500 time (d) U Np Pu Am Cm U Np Pu Am Cm
  21. 21. 48 MBU Dissolution & normalized rates for Actinides CORE 1.E-08 1.E-09 1.E-10rates (mol m-2 s-1) 1.E-11 1.E-12 1.E-13 1.E-14 1.E-15 0 50 100 150 200 250 300 350 time (d) U Np Pu Am Cm OUT OUT 1.E-06 1.E-06 1.E-07 1.E-07 1.E-08 normalised rates (mol m s-1) -2 1.E-08 rates (mol m s-1) 1.E-09 -2 1.E-10 1.E-09 1.E-11 1.E-12 1.E-10 1.E-13 1.E-11 1.E-14 1.E-15 1.E-12 0 50 100 150 200 250 300 350 0 50 100 150 200 250 300 350 time (d) Time (days) U Np Pu Am Cm U Np Pu Am Cm
  22. 22. Results CORE OUT CORE OUT 60HBU 60HBU 48MBU 48MBUNORMALIZED RATE (mol/m2 s) U 5.1 10-12 2.1 10-12 8.0 10-11 4.0 10-11 Np 1.6 10-10 5.2 10-11 1.0 10-10 8.0 10-11 Pu 1.0 10-11 5.7 10-12 3.0 10-11 1.4 10-11 Am 3.5 10-12 2.5 10-12 5.0 10-11 2.0 10-11 RATIO Np/U 11.3 15.2 1.4 2.2 Pu/U 1.2 1.7 0.4 0.4 Am/U 0.4 0.6 0.7 0.7
  23. 23. Some remarks Uranium and Actinide dissolution rates are twice faster in the CORE region than in the Periphery Except for Np in 60HBU fuel, actinides dissolve congruently with uranium Uranium dissolution rate is lower in 60HBU fuel than in 48MBU fuel
  24. 24. 60HBU Normalized Rates for Fission Products CORE OUT 1,E-07 1,E-07normalized rates (mol/m 2.s) 1,E-08 1,E-08 normalized rates (mol/m2.s) 1,E-09 1,E-09 1,E-10 1,E-10 1,E-11 1,E-11 1,E-12 1,E-12 1,E-13 1,E-13 1,E-14 1,E-14 0 100 200 300 400 500 0 100 200 300 400 500 time (d) time (d) Rb Sr Y Zr Mo Tc Ru Rh Cs Nd U Rb Sr Y Zr Mo Tc Ru Rh Cs Nd U
  25. 25. 48MBU Normalized Rates for Fission Products CORE OUT 1.E-07 1.E-06 1.E-07 normalised rates (mol m-2 s-1) 1.E-08normalised rates (mol m-2 s-1) 1.E-08 1.E-09 1.E-09 1.E-10 1.E-10 1.E-11 1.E-11 1.E-12 1.E-12 1.E-13 1.E-13 0 50 100 150 200 250 300 350 0 50 100 150 200 250 300 350 times (t) time (d) Rb Sr Y Zr Mo Tc Ru Rh Cs La Nd U Rb Sr Y Zr Mo Tc Ru Rh Cs La Nd U
  26. 26. Results Ratio CORE OUT CORE OUT 60HBU 60HBU 48MBU 48MBU Rb/U 25.4 113.7 11.0 4.0 Sr/U 7.7 16.2 3.5 1.4 Y/U 1.8 1.7 2.3 3.0 Zr/U 0.02 0.04 0.2 0.1 Mo/U 4.1 29.7 4.2 2.0 Tc/U 0.5 0.5 1.3 1.1 Ru/U 0.3 0.8 0.3 0.7 Rh/U 0.2 0.5 0.3 0.8 Cs/U 2.0 40.2 10.0 3.1
  27. 27. Results: FP rates/ U rate 120,00 100,00 80,00 dissolution rate ratio 60core 60,00 60out 48core 48out 40,00 20,00 0,00 Rb/U Sr/U Y/U Zr/U Mo/U Tc/U Ru/U Rh/U Cs/U
  28. 28. Some remarks Fission products normalized dissolution rates are similar in 48MBU for both core and out samples Fission products normalized dissolution rates are higher in out than in core samples in 60HBU Rb, Sr, Mo, Cs are more segregated from UO2-grains in 60HBU than in 48MBU
  29. 29. Matrix dissolution rate comparison -9.00 Gray_33 MW d/kgU Röllin_43 MW d/kg U this_work_6OHBU_out this_work_60HBU_core Serrano_53 MW d/kg U this_work_48MBU_core this_work_48MBU_out -9.50 -10.00log rate -10.50 -11.00 -11.50 -12.00 -4.50 -4.00 -3.50 -3.00 -2.50 -2.00 -1.50 -1.00 log [HCO3-]
  30. 30. Conclusions -phase Dissolution lowerUO2-matrix dissolution rate than UO2-matrix Grains similar in both HBUhigher in MBU than in HBU Grains and MBU fuels Gap Rim Boundaries IRF 2 options: Not studied in this  IRF or 2 options Congruent dissolution  matrix  IRF or with UO2-matrix: work, no gap was  matrix present Np, Pu, Am, Cm, excep t for Np in 60HBU. This work indicates that High BU Rb, Sr, Cs, Mo are Structure (RIM) can not be more segregated from considered IRF. OUT Dissolution UO2-grains in 60HBU rate (including a percentage of RIM) than in 48MBU lower than CORE rate for both HBU and MBU Not studied in detail in this work, only 3% of grain boundary present
  31. 31. THANK YOU FOR YOUR ATTENTION GRACIAS POR SU ATENCIÓNAnd thanks to Argentina for sendingthis guy to Barcelona Que bueno que viniste

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