R adioiodine W aste M anagement by C old S intering of C eramic M atrices

1. Radioiodine Waste Managementby Cold SinteringofCeramic Matrices Nuclear Fuel Materials Lab Department of Nuclear and Quantum Engineering Korea Advanced Institute of Science and Technology (KAIST) S. Korea March 26, 2019 Muhmood ul Hassan, Ph.D. Candidate Prof. Ho Jin Ryu, Ph.D. European Research Reactor Conference 2019 (RRFM/IGORR 2019) Crown plaza Dead Sea Resort, Jordan, March 24-28, 2019

2. Motivation • In conventional high temperature sintering; • Temperature higher than 900 oC • Long sintering time >60 min • Possible volatilization of volatile radionuclides • Therefore low temperature sintering techniques need • to be developed and investigated H. Guo, A. Baker, J. Guo et al., J. Am. Ceram. Soc., 3489–3507 (2016) Hassan et al. J. Nucl. Mater., 84-89 (2019)

3. Generation of I-129 Composition of Spent Nuclear Fuel (SNF) Fission Yield of iodine isotopes (%/fission) • Major sources of I-131 & I-129; • Radioisotope production (Mo-99 extraction process) • Spent nuclear fuel (SNF) is considered as Marques et al., Radioactive Waste: Sources, Types and Mnagment, 2017

4. Immobilization of I-129 The primary role of a waste form is to immobilize radioactive and hazardous constituents in a stable, solid matrix for disposal. Two essential characteristics of the waste forms are; 1. Loading capacity 2. Durability Glass (e.g. Borosilicate glass) Cement Minerals & Ceramics (e.g. SYNROC, apatite, sodalite, nephline) Advantages and Disadvantages • Can accommodate a wide range of waste • Good chemical, thermal and mechanical stabilities • High Temperature Processing >600 °C (Glass) • Low loading (in case of some glasses) • Low leaching rates (cements) Apart from the reasonable durability of the developed matrix, easy processing techniques are still demanded National Research Council. (2011). Waste Forms Technology and Performance. https://doi.org/10.17226/13100

5. Solidification of Waste FormsSintering • Conventional sintering of ceramics • Requires ultra high temperature • Longer sintering time • Higher energy consumption • Greater chances of decomposition Kang et al. Sintering, densification, grain growth and microstructure, 2005.

6. Solidification of Waste FormsSintering Advanced sintering techniques for ceramics consolidation 3. Spark plasma sintering 1. Microwave sintering 2. Flash Sintering 5. Hydrothermal sintering 4. High pressure sintering However, these techniques still requires temperature > 500 °C

7. Cold Sintering (CS) • Cold sintering is a very low temperature process • Driven by transient solvent • Assisted by applied pressure • Temp. range 25 °C to 300 °C • Pressure range 50 MPa to 500 MPa (Uniaxial) J. Guo et al., Cold Sintering: A paradigm shift for processing and integration of ceramics, 2016.

8. Materials of Interest Calcium Hydroxyapatite- Ca5(PO4)3OH& Sodalite-Na8(AlSiO4)6I2 M5(XO4)Z M- Na+, K+, Cs+, Mg2+, Ca2+, Ba2+, Sr2+, Cd2+, Pb2+, Fe2+, Fe3+, REE X- P5+, Si4+, S6+, V5+, Cr5+, As5+, Mn5+, Ge4+ Z- OH−, F−, Cl−, Br, I−, O2−, CO2−3, and IO−3 Sodalite is a microporous mineral M- Na+, Ag+, Cs+, Li+ X- OH−, Cl−, Br, I−, and IO−3 Pb5(PO4)3Cl (pyromorphite), Pb5(VO4)3Cl (vanadinite), Pb5(AsO4)3Cl (mimetite), Pb10(VO4)6I2(lead vanadate iodoapatite), Ca10(PO4)6(IO3)x(OH)2-x (iodate-substituted hydroxyapatite) Kinoshita et al. Development of advanced radioactive waste conditioning technologies, 2011 Chong et al., Glass-bonded iodosodalite waste form for immobilization, J. Nuc. Mater., 2018

9. Ceramic Based Waste Forms Iodine is not amenable to conventional vitrification and cementation routes as it has low solubility in vitreous waste- forms, it is volatile at processing temperatures and its anions are highly soluble in cement pore water (Lee et al., Immobilisation of radioactive waste in glasses, GCMs and ceramics, Advances in applied ceramics, 2006.) *A. Coulon et al., J. Eur. Ceram. Soc., vol. 36, no. 8, pp. 2009–2016, 2016. **L. Campayo, S. Le Gallet, Y. Grin, E. Courtois, F. Bernard, and F. Bart, J. Eur. Ceram. Soc., vol. 29, no. 8, pp. 1477–1484, 2009. ***M. C. Stennett, I. J. Pinnock, and N. C. Hyatt, J. Nucl. Mater., vol. 414, no. 3, pp. 352–359, 2011. ****T. Yao, F. Lu, H. Sun, J. Wang, R. C. Ewing, and J. Lian, J. Am. Ceram. Soc., vol. 97, no. 8, pp. 2409–2412, Aug. 2014. Chong et al., J. Nuc. Mater., 2018 Maddrell et al. J. Nuc. Mater., 2019

10. Synthesis and Characterization of IO-HAP Region of iodine volatilization Wet Precipitation Method Region of Moisture loss 20 nm 5 nm Crystal Size= 34.9 nm , SSA= 62.1±2.1 m2g-1 Density = 2.94 gcm-3, I wt.% = 7 (ICP-OES) Nano IO-HAp

11. Synthesis and Characterization of IO-SODA Hydrothermal Synthesis 2NaI +3Al2Si2O7+ 6NaOH + xH2O→Na8(AlSiO4)6I2 + (3 + x) H2O Synthesis Temperature: 180 °C Time : 48 h Drying (Post Synthesis): 120 °C overnight Crystal Size= 55.7nm , SSA= 12.5m2g-1 Density = 2.41 gcm-3, I wt.% = 12.20 ± 0.02

12. Cold Sintering (CS) Uniaxial Press Coating Zirclaoy-4 tube Water Coolant Stainless Steel Mold Heating Jacket Temperature Controller

13. Cold Sintering (CS) of IO-HAP Effect of Pressure Effect of Temperature Effect of Holding Time Coating Zirclaoy-4 tube Water Coolant TEM of Cold Sintered Sample SEM of fractured surface Sintered Relative Density = 97% Average Grain Size = <50 nm

14. Cold Sintering (CS) of IO-SODA Effect of Temperature Effect of Pressure SEM dried iodosodalite (A), polished (B) and fractured (C) surface of cold sintered samples TEM images of cold sintered samples Coating Zirclaoy-4 tube Water Coolant Sintered Relative Density = 98% Average Grain Size = <50 nm

15. Cold Sintering (CS) of IO-HAP and IO-SODACompressive Strength & Micro Hardness • Micro hardness of the CS IO-HAp samples • Vickers microindentor • (Model: 402MVD, Wolpert Wilson Instruments) • Applied Load = 200 g • Dwell Time =10 sec • Measured Value = 2.17 ± 0.23 GPa (IO-HAP) • = 3.88 ± 1.4 GPa (IO-SODA) Compressive strength of the CS IO-HAp samples was measured by using ASTM C39 Standard Waste Acceptance Testing of Secondary Waste Forms : Cast Stone, Ceramicrete and DuraLith, U.S. Dep. Energy, PNNL-20632, (2011) Martin Brownstein G.T.S Duratek Kingston, Tennessee, Radioactive Waste Solidification, (1991).

16. Product Consistency Test (PCT)Chemical Durability Standard Followed = ASTM-1285 Sample = 1 g crushed & sieved powder Leachant = ASTM Type-I Water Test Temperature = 90 ± 2 oC Duration = 7 days NLRi = Normalized Leaching Rate of ithElement mi = Concentration of component ileached into water after a reaction time t, S = Surface area of the crushed powder wi = Weight fraction of an ith component in a solid matrix Very low Normalized Leaching Rates makes the cold sintered IO-HAP and IO-SODA suitable candidates for I-129 immobilization Low Temperature Waste Immobilization Testing, Pacific North west laboratory, PNNL-16052 Rev. 1 (2006)

17. Conclusion • We have first time sintered the IO-HAP and IO-SODA at 200 & 300 °C • There sintered relative densities were > 97% • There was no loss of loaded iodine during the sintering process • The cold sintered samples have shown compressive strength higher than the regulatory requirements of the USA and the Russia • The cold sintered samples have shown very low leaching rates • Our methodology is; • less prone to contamination due to low temperature • energy efficient and reproducible on larger scale Thus the demonstrated cold sintering can be a suitable process for the immobilization of volatile radionuclides using ceramic based matrices

18. Thank you

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