Cs and other radionuclides retention by geochemical and engineered barriers

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1 137 Cs and other radionuclides retention by geochemical and engineered barriers Stepan. Kalmykov uclear Russia Source Volume (m 3 ) Activity (Ci) Uranium ore mining and treatment , Isotope enrichment and fuel production 1, uclear power stations , Radiochemical enterprises activities Submarine and ice-boat operation , , Submarine utilization Isotope sources 2, , As a result more than 600 Mm 3 of nuclear wastes were accumulated with total activity of 2.5 billion Ci

2 uclear Russia Radionuclide speciation and local (nanoscale) distribution in samples collected at the contaminated sites Techniques available in MSU: UR TEM (JEL 2500), μ-xps, Auger and SIMS (Kratos), XAFS (2.5 GeV line at Kurchatov Institute in Moscow ), TRLIF additionally: anosizer ano-zs (Malvern), SIMS, SAXS, etc. Alpha- track and fission track analysis

3 SIMS Primary Ions Secondary Ions -Fe 2 3 Sample Mass 27 Mass 29 Mass 55 Mass Al Mn 238 U 16 Pu 2+x n 2 Pu- R TEM Pu-Fe Pu-Pu EXAFS Sources of radioactive contamination of South Ural Dec. 22, 1948 the plant to separate weapon grade Pu from irradiated uranium was launched Production capacity was around 1 ton of U blocks per day about 10 5 Ci of wastes

4 Year before the plant was launched, complex C was constructed that is the assembly of tanks for LW. The capacity was estimated around m 3 per year. owever the real volume of wastes was 200 m 3 per day. All tanks were filled with LW before 1950 (about a year after the plant was launched). The construction of new tanks for LW was too expensive. From 1949 till 1951 wastes were disposed to Techa river. During this period c.a. 76 Mm 3 of waste solutions were disposed equal to 2.8 MCi. Volume of waste disposed to Techa river I-XI.1949 XII II.1950 III XI.1951 Total -activity, Ci/day Sr + 140, % Sr, % Zr + 95 b, % ,106 Ru, % Cs, % REE, %

5 Creation of Techa cascade of reservoirs D-1 Irtyash lake August 1951 D-1 Irtyash lake September Kyzyltash lake(r-2) D-4 Kyzyltash lake (R-2) D-3 D-4 D-2 R-4 D-2 R-3 R-4 LRW discharge Contaminated flood-plain of the r.techa LRW discharge Contaminated flood-plain of the r.techa r.mishelyak r. Techa r.mishelyak r.techa Irtyash lake Irtyash lake since 1965 D-1 Release of conditionally clean water from R-2 Kyzyltash lake (R-2) D-3 D-4 LBC D-2 R-3 R-4 R-10 D-10 Contaminated LRW discharge swamped RBC flood-plain of the r. Techa r.mishelyak r.techa D-1 Clean water drain Kyzyltash lake (R-2) D-3 D-4 R-3 D-2 R-4 LRW discharge r.mishelyak LBC Clean water drain R-10 D-10 RBC D-11 R-11 r.techa Contamination of flood plain soils, kbq/m 2. Location 90 Sr 137 Cs 239,240 Pu Right bank ,2-16,4 Left bank ,3-2,0 Bq/kg Strontium Depth, cm Cesium-137 Bq/kg Cs binding: Competition between clays and organic matter Depth, cm Plutonium Bq/kg Depth, cm

6 Cs-137 distribution with soil types Increase of clay content Increase of humic content The dependence of diffusion resistance of various soils to 137 Cs, 90 Sr and 239 Pu vertical migration upon As concentration

7 Industrial reservoirs at Mayak site In 1951 the disposal of wastes to Techa was stopped and changed to lake Karachay that don t have connection with open hydrological system. LLW and ILW were also disposed to 8 artificial reservoirs: B-2 (lake Kiziltash), -3, -4, -10, -11, -6, -17 (called also ld Swamp) and -9 (lake Karachay). About 120 MCi ( Bq) of beta-emitters and 1 MCi ( Bq) of alphaemitters were disposed. Industrial reservoirs at PA Mayak

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9 Deconvolution of the average C1S spectra of humic-mineral aggregates Functional group Content, % C=C, C- 14 Phenol 9 Aliphatic 15 Carboxyl 37 Carbonyl 25 Deconvolution fit of sample with different carbon functionalities as indicated by the labels. The open dots represent the smoothed measured spectra obtained by cluster analysis and the red line indicated the fitted spectra STXM From left to right, upper row; absorption image at 280eV below the C1s edge; ratio images showing the distribution of aromatics, phenol-type groups and lower row aliphatics, carboxyl-type groups and total organics. Bright grey values indicate high concentrations of organic functionality

10 0,30 0,25 F colloids in Mayak groundwater F colloids in a3 brine solution Effect of organics on colloid particle stability Stabilizing effect of organics XPS, Auger microscopy with ion etching Rel. amplitude 0,20 0,15 0,10 0,05 0,00 1 2, Colloid size, nm C (C1s XPS) Fe (2p3/2 XPS) rganic coating Inorganic central part 15 At. % Surface 100 A 200 A Penetration of various radionuclides and 3- by geological media Radioactivity, Bq/l U, mg/l Sr-90, Bq/L Cs-137, Bq/L 3-, mg/l , mg/l distance, m

11 Approaches for barriers design Bentonite clays Immobilized humic derivatives Carbon nanomaterials Khakassiya bentonite Cs(I) sorption onto bentonite p(v) sorption onto bentonite I=0,001 I=0,01 I-0, I=0,001 I=0,01 I-0,1 Kd, / 100 Kd, / p p

12 C 2 2 C 2 C C C - - C 3 2 C3 2 C3 C 2 C C 2 C 2 C 2 2 C 2 Fe 2 3 C C 2 - C C 2-3 C 2 C 2 C2 C 2 2 C C C C Fe 2+ C C C 2 C C 3 3 C 2 C 2 2 C 3 C 3 Fe 2+ C C 3 C C 2 C 2 - C 2 C C 2 C 2 C 2 C 2 C 2 C 2 C 2 Al Al + Fe 2 3 C C 2 C C 2 C 2 Fe 2+ C Fe 2+ C 3 3 C - 2 C 3 C 3 C 2 C 2 C 2 C 2 C C C C C Fe 2+ C C C - 2 C C 3 3 C 2 C 2 2 C 3 C 3 C 2 2 K + Fe 2+ 2 C - 3 C C 2 C 2 - C 2 C C 2 C 2 C 2 C 2 C 2 C 2 C 2 Al Al + Fe 2 3 C C 2 C C 2 C 2 Fe 2+ C Fe 2+ C 3-3 C - 2 C 3 C 3 C 2 C 2 C C 2 2 C 2 C K + C 2 C 2 C 2 C 2 Khakassiya bentonite Cs(I) sorption onto bentonite I=0,001 I=0,01 I-0,1 logk p(v) ie = 1.7 sorption onto bentonite I=0,001 I=0,01 I-0,1 Kd, / 100 Kd, / p p In collaboration with Irina Perminova, MSU C 2 Preparation of alkoxylenated derivatives of humic acids with various organosilans C 2 K + - C C 3 C2 C 3 C 2 C C2 C C C2 C 2 C C 3 C 3 C 2 C2 C2 C 2 - C 2+ Fe 2 2 C 2+ Fe 2+ Fe Al 3 C Fe 2+ Al + R 1 2 (R) 3 R 1 rganosilan Structure R R C 2 R R R R R R R R R R Amino Epoxy Isocyanate 3-aminopropyl-trialkoxysilane (APTS) 3-glycidoxypropyl-trialkoxysilane (GPTS) 3-isocyanatopropyl-trialkoxysilane (IPTS) 2 (C 2 ) 3 (R) 3 C(C 2 ) 3 (R) 3

13 umic sorbents on 2 support AFM-of S surface layers Karpiouk et al. Soft Matter 2012, 8 (8), 2452

14 Example: Pu sorption 90% mulation of permeable reaction barrier p 10, S 2.5 %, M p 10, S 2.5 %, M

15 Aminoorganosilane formation of micelles 2 S 5 C 2 C C 2 5 n n n S - n + n- n + 3 n S - n + n- n + 3 n Stabilization of zero valent Fe nanoparticles by S ab 4 p 7 Fe 0 2 (Et) Fe (C 2 ) 3 () () 3 () 3 () 3 Fe 0 () 3 () 3 Fe 0 60% Fe % 2 () 3 () 3

16 Iron oxides nanoparticles stabilized by S K-CS ( ) % FeCl 2 Fe() 2-2 -Fe -Fe Formation of -Fe in the presence of S 100 / 1000 / l=160±100 l=20±5 l=17±7 d=20±5 d=2±1 d=2,5±1,5 32

17 In collaboration with James Tour, Rice University Carbon nanomaterials as effective scavengers for radionuclides Graphene oxide ummer modified method Graphite + KMn 4 9:1 2 S 4 3 P 3 Marcano et al., ACS ano, 2010 Earlier the effective scavenging of actinides and lanthanides was shown 100 Ñî ðáöèÿ, % Th(IV) Pu(IV) Am(III) Eu(III) U(VI) Quantitative sorption: p Th(IV), Pu(IV) p> 1,5 Am(III), Eu(III) p> 2,3

18 Qmax, / U(VI), p = 3,5 97 ± 19 U(VI), p = 5,0 116 ± 5 Sr(II), p = 6,5 272 ± 35 Cs(I), p = 7,0 160 ± 75 G + Cs(I) Distribution of Cs(I) on the surface Cations + G AADF-STEM

19 Coagulation of G p = 3 p = 7 a + - 0,4 M Ca 2+ 0,007 M 0,001M Eu 3+ < M < M Conclusions: 1. As expected, clays effectively sorb Cs +, but the presence of humic could change the mobility of Cs +, 2. umics form stable surface coatings on mineral particles that change their sorption and coagulation properties, 3. umics could be easily modified and immobilized onto silica surfaces, as a result permeable barrier could be formed, 4. Graphene oxide could be considered as an effective scavenger for cationic forms of radionuclides.