skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Reactive amendment saltstone (RAS). A novel approach for improved sorption/retention of radionuclides such as technetium and iodine

Abstract

This study examined the use of reactive amendments (hydroxyapatite, activated carbon, and two types of organoclays) that prior research suggests may improve retention of 99Tc and 129I. Tests were conducted using surrogates for 99Tc (NaReO 4) and 129I (NaI). Results showed that adding up to 10% of organoclay improved the retention of Re without adversely impacting hydraulic properties. To a lesser extent, iodine retention was also improved by adding up to 10% organoclay. Numerical modeling showed that using organoclay as a reactive barrier may significantly retard 99Tc release from saltstone disposal units.

Authors:
 [1];  [1];  [1];  [1];  [1]
+ Show Author Affiliations
  1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
Publication Date:
Research Org.:
Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1225176
Report Number(s):
SRNL-STI-2015-00594
TRN: US1500843
DOE Contract Number:
AC09-08SR22470
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; TECHNETIUM 99; IODINE 129; ACTIVATED CARBON; SODIUM IODIDES; APATITES; CLAYS; SORPTION; SODIUM OXIDES; RHENIUM OXIDES; COMPUTERIZED SIMULATION; CONTAINMENT; RADIOISOTOPES; HYDRAULICS; RHENIUM; SODIUM NITRATES; CONCRETES; FLY ASH

Citation Formats

Dixon, K. L., Knox, A. S., Cozzi, A. D., Flach, G. P., and Hill, K. A.. Reactive amendment saltstone (RAS). A novel approach for improved sorption/retention of radionuclides such as technetium and iodine. United States: N. p., 2015. Web. doi:10.2172/1225176.
Copy to clipboard
Dixon, K. L., Knox, A. S., Cozzi, A. D., Flach, G. P., & Hill, K. A.. Reactive amendment saltstone (RAS). A novel approach for improved sorption/retention of radionuclides such as technetium and iodine. United States. doi:10.2172/1225176.
Copy to clipboard
Dixon, K. L., Knox, A. S., Cozzi, A. D., Flach, G. P., and Hill, K. A.. Wed . "Reactive amendment saltstone (RAS). A novel approach for improved sorption/retention of radionuclides such as technetium and iodine". United States. doi:10.2172/1225176. https://www.osti.gov/servlets/purl/1225176.
Copy to clipboard
@article{osti_1225176,
title = {Reactive amendment saltstone (RAS). A novel approach for improved sorption/retention of radionuclides such as technetium and iodine},
author = {Dixon, K. L. and Knox, A. S. and Cozzi, A. D. and Flach, G. P. and Hill, K. A.},
abstractNote = {This study examined the use of reactive amendments (hydroxyapatite, activated carbon, and two types of organoclays) that prior research suggests may improve retention of 99Tc and 129I. Tests were conducted using surrogates for 99Tc (NaReO4) and 129I (NaI). Results showed that adding up to 10% of organoclay improved the retention of Re without adversely impacting hydraulic properties. To a lesser extent, iodine retention was also improved by adding up to 10% organoclay. Numerical modeling showed that using organoclay as a reactive barrier may significantly retard 99Tc release from saltstone disposal units.},
doi = {10.2172/1225176},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Sep 30 00:00:00 EDT 2015},
month = {Wed Sep 30 00:00:00 EDT 2015}
}
Copy to clipboard
Technical Report:
View Technical Report
DOI:  10.2172/1225176
Save / Share:
Export Metadata
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.

  • ; ;
    Before testing the performance characteristics of andisols for retention of anions in the near-field environment of Low Level Wastes (LLW) disposal facilities it is necessary to locate one or more sufficiently extensive bodies of natural soil with the highest possible natural anion exchange capacity. For this purpose we developed a rugged, portable semiquantitative field test for anion exchange capacity based on short-term sorption of iodide by soil samples. We validated the iodide sorption field test against a well established quantitative laboratory test based on anion exchange of chloride and nitrate, then carried out an initial survey of volcanic terrain inmore » northern California using the field test.« less

  • ; ;
    Before testing the performance characteristics of andisols for retention of anions in the near-field environment of Low Level Wastes (LLW) disposal facilities it is necessary to locate one or more sufficiently extensive bodies of natural soil with the highest possible natural anion exchange capacity. For this purpose we developed a rugged, portable semiquantitative field test for anion exchange capacity based on short-term sorption of iodide by soil samples. We validated the iodide sorption field test against a well established quantitative laboratory test based on anion exchange of chloride and nitrate, then carried out an initial survey of volcanic terrain inmore » northern California using the field test.« less

  • ;
    This report summarizes a literature review of our present knowledge of the anion exchange properties of a number of soils and minerals, which may potentially be used as anion exchangers to retard migration of such anions as iodide (I{sup {minus}}), iodate (IO{sub 3}{sup {minus}}) and pertechnetate (TcO{sub 4}{sup {minus}}) away from disposal site. The amorphous clays allophane and imogolite, are found to be among the most important soil components capable of developing appreciable amounts of positive charge for anion exchange even at about neutral pH. Decreases in the SiO{sub 2}/Al{sub 2}O{sub 3} ratio and soil pH result in an increasemore » in soil AEC. Allophane and imogolite rich soils have an AEC ranging from 1 to 18 meq/100g at pH about 6. Highly weathered soils dominated by Fe and Al oxides and kaolinite may develop a significant amount of AEC as soil pH falls. The retention of iodine (I) and technetium ({Tc}), by soils is associated with both soil organic matter, and Fe and Al oxides, whereas sorption on layer silicate minerals in negligible. Fe and Al oxides become more important in the retention of anionic I{sup {minus}}, IO{sub 3}{sup {minus}}, and TcO{sub 4}{sup {minus}} as pH falls, since more positive charge is developed on the oxide surfaces. Although few studies, if any, have been conducted on I and {Tc} sorption by soil allophane and imogolite, it is estimated that a surface plough soil (2 million pounds soil per acre) with 5 meq/100g AEC, as is commonly found in andisols, shall retain approximately 5900 kg I and 4500 kg {Tc}. It is conceivable that an anion exchanger such as an andisol could be used to modify the near field environment of a radioactive waste disposal facility. This whole disposal system would then offer similar migration resistance to anions as is normally afforded to cations by usual and normal soils. 93 refs., 10 figs., 7 tabs.« less

  • ;
    Burial of vitrified low-level waste (LLW) in the vadose zone of the Hanford Site is being considered as a long-term disposal option. Regulations dealing with LLW disposal require that performance assessment (PA) analyses be conducted. Preliminary modeling efforts for the Hanford Site LLW PA were conducted to evaluate the potential health risk of a number of radionuclides, including Ac, Am, C, Ce, Cm, Co, Cs, Eu, 1, Nb, Ni, Np, Pa, Pb, Pu, Ra, Ru, Se, Sn, Sr, Tc, Th, U, and Zr (Piepho et al. 1994). The radionuclides, {sup 129}I, {sup 237}Np, {sup 79}Se, {sup 99}Tc, and {sup 234,235,238}U,more » were identified as posing the greatest potential health hazard. It was also determined that the outcome of these simulations were very sensitive to the parameter describing the extent to which radionuclides sorbed to the subsurface matrix, described as a distribution coefficient (K{sub d}). The distribution coefficient is a ratio of the radionuclide concentration associated with the solid phase to that in the liquid phase. The literature-derived K{sub d} values used in these simulations were conservative, i.e., lowest values within the range of reasonable values used to provide an estimate of the maximum health threat. Thus, these preliminary modeling results reflect a conservative estimate rather than a best estimate of what is likely to occur. The potential problem with providing only a conservative estimate is that it may mislead us into directing resources to resolve nonexisting problems.« less

  • ; ; ; ...
    An assessment of long-term performance of Category 3 waste-enclosing cement grouts requires data about the leachability/diffusion of radionuclide species (iodine-129, technetium-99, and uranium) when the waste forms come in contact with groundwater. Leachability data were collected by conducting dynamic (ANS-16.1) and static leach tests on radionuclide-containing cement specimens. The diffusivity of radionuclides in soil and concrete media was collected by conducting soil-soil and concrete-soil half-cell experiments.