Effect of Dimension of Specimen on Amounts of Cesium-137, Strontium-90 and Cobalt-60 Leached from Matrix of Hardened Cement Grout

Matsuzuru, Hideo; Ito, Akihiko

doi:10.3327/jnst.15.296

Cited by 11 publications

(5 citation statements)

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“…In the dy namic per for mance of the ex per i ment, fluid cir cu la tion around a sam ple of the ce ment ma trix is car ried out with its con stant depth de ple tion for the ob served ion, thereby es tab lish ing a higher con cen tration gra di ent than in the static per for mance of the exper i ment [26]. Con se quently, higher val ues of the effec tive diffusivity co ef fi cients, D e , as well as the higher val ues of the con stants K 1 and K 2 in the semi-em pir i cal leach ing model are es tab lished.…”

Section: Re Sults and Discussionmentioning

confidence: 99%

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Leaching kinetics of Cs+ and Co2+ under dynamic conditions

et al. 2019

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The pos si bil ity of re tain ing Cs + and Co 2+ bound by im mo bi li za tion pro cesses in the ce ment ma trix is de fined as the sub ject of its in ves ti ga tion: the ce ment ma trix for mu la tion, the water/ce ment ra tio, the amount of waste, and the po ros ity of such a struc ture. Im ple ment ing the stan dard leach ing method by Hespe the pos si bil ity of com par ing dif fer ent au thors' re sults was achieved. Dif fu sion and semi-em pir i cal model were used to in ves ti gate the trans port phenom e non in or der to pre dict the leach ing level for a long pe riod of time. Leach ing of Co 2+ and Cs + ions un der dy namic con di tions im mo bi lized in the ce ment ma trix dy namic con di tions decreases with the in crease of the sludge con tent, re gard ing po ros ity in crease. The ef fects of the dif fu sion and sur face wash ing are equal ized, and the con tri bu tion of the ma trix dis so lu tion to the Cs + and Co 2+ trans port in the ce ment po rous me dia in creases, on av er age, for one or der of mag ni tude. The semi-em pir i cal model gives a better ap prox i ma tion for Co 2+ and Cs + leaching pro cess for the du ra tion of the ex per i ment while both mod els sig nif i cantly ap prox i mate leach ing re sults in dy namic con di tions.

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Section: Re Sults and Discussionmentioning

confidence: 99%

“…In con sid er ation of all this, it be comes clear why the leach ing level of Co 2+ and Cs + ions in dy namic is in com pa ra bly greater than that in static con di tions. [26][27][28]. As ex pected, the leach ing for Cs + is al most three or ders of mag ni tude greater than for Co 2+ .…”

Section: Re Sults and Discussionmentioning

confidence: 99%

Leaching kinetics of Cs+ and Co2+ under dynamic conditions

et al. 2019

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“…In general, portland cement evidences a rapid release of cesium in leaching experiments while strontium and cobalt leach substantially less readily [1][2][3]10,11,29,[51][52][53][54][55][56][57][58]. As a result, sorbents for cesium are commonly blended with cement to reduce its leachability [51][52][53][54][55][56][57][58][59][60][61]. These blended cement + sorbent mixtures are often formulated for specific waste streams.…”

Section: Portland Type I Cement Containing Sodium Sulfate Salt As Simmentioning

confidence: 99%

“…53 Outer surface of an unleached cement sample containing 5% sodium sulfate at a magnification of 400 times. This surface is indistinguishable from that of unleached pure cement 65…”

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confidence: 99%

An experimental survey of the factors that affect leaching from low-level radioactive waste forms

Dougherty¹,

Pietrzak²,

Fuhrmann³

et al. 1988

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“…Empirically, the surface wash has been accounted for by including a constant in the leaching release equation which represents an instantaneous release [61][62][63][64][65]. The form of the equation referenced in [61][62][63][64][65] is shown in equation 8. In general, mechanistic modelling which does not include a surface wash does not result in an expression which includes a constant.…”

Section: Initial Surface Wash In Leachmentioning

confidence: 99%

Accelerated Leach Test(s) Program: Annual report

Dougherty¹,

Pietrzak²,

Fuhrmann³

et al. 1986

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LIST OF FIGURES Figure No. Page 3.1 Compositional phase diagram for the solidification of aqueous waste containing 50 wt% or less ^SQ, with portland type I cement 8 3.2 Ternary compositional phase diagram for the solidification of incinerator ash in portland type I cement 8 3.3 Sodium ion concentrations released from vinyl ester-styrene/sodiurn sulfate waste forms after 3 day immersion in deionized water at 20°C versus waste loading 10 4.1 Cumulative fraction releases from portland cement for Sr-85 and Cs-137. No release of Co-60 was detected 21 4.2 Cumulative fraction releases for Cs-137 from portland cement. Final release was 0.817 of total activity in the waste form 23 4.3 Rate of Cs-137 release from portland cement. Note the change of rate between 10 and 20 days 23 4.4 Cumulative fraction release for portland cement samples. Data only goes out to 144 days because of radioactive decay of the i sotope 24 4.5 Release rates of Sr-85 from portland cement 24 4.6 Cumulative fraction releases of Cs-137, Sr-85, Co-60 from a vinyl ester-styrene emulsion waste form 25 4.7 Cumulative fraction releases of Cs-137 from triplicate VES emulsion waste forms. Note the scale used on the y-axis makes a small difference seem large « 26 4.8 Release rates for Cs-137 from triplicate VES emulsion waste forms. The scatter at the lower right of the plot indicates larger counting errors due to low release rates 26 4.9 Cumulative fraction releases for Sr-85 from VES emulsion waste forms. These data extend only to 144 days because radioactive decay reduced the count rate to detection limit activities 27 4.10 Release rates for Sr-85 for triplicate VES emulsion samples 27 4.11 Cumulative fraction releases for Co-60 from triplicate vinyl ester-styrene emulsion samples 28-viii-LIST OF FIGURES (cont.) Figure No. Page 4.12 Release rates of Co-60 from triplicate vinyl ester-styrene samples. Scatter at the bottom right is due to relatively large counting errors resulting from low release rates 29 4.13 Cumulative fraction releases for Cs-137, Co-60 and Sr-85 from bitumen. The isotopes from this material leach at different rates, unlike those in VES emulsion samples 28 4.14 Cumulative fraction releases of Cs-137 from triplicate bitumen waste forms. Note the scale of the y-axis indicating that intersample variability is quite small 31 4.15 Release rates of Cs-137 from triplicate bitumen samples 31 4.16 Cumulative fraction releases of Sr-85 for triplicate bitumen sampl es 32 4.17 Release rates of Sr-85 for triplicate bitumen samples 32 4.18 Cumulative fraction releases of Co-60 from triplicate bitumen waste forms. Note the scale of the y-axis 33 4.19 Release rates of Co-60 from triplicate bitumen samples. The scatter at the bottom right is due to large counting errors caused by low release rates 33 4.20 Cumulative fraction releases of Cs-137 from cement, VES emulsion and bitumen samples. While VES and bitumen have similar low fraction releases that of cement is 82% of the total original activity 34 4.21 Plot of conductance (umhos/cm) versus alkalinity...

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Effect of Dimension of Specimen on Amounts of Cesium-137, Strontium-90 and Cobalt-60 Leached from Matrix of Hardened Cement Grout

Cited by 11 publications

References 0 publications

Leaching kinetics of Cs+ and Co2+ under dynamic conditions

Leaching kinetics of Cs+ and Co2+ under dynamic conditions

An experimental survey of the factors that affect leaching from low-level radioactive waste forms

Accelerated Leach Test(s) Program: Annual report

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