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Title: A Highly Selective and High Efficiency Smart Sorbent for Iodine-129

Authors:
 [1]
  1. NEI Corporation, Somerset, NJ (United States)
Publication Date:
Research Org.:
NEI Corporation, Somerset, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
Contributing Org.:
Washington State University
OSTI Identifier:
1349642
Report Number(s):
DOE-NEI-43136
43136
DOE Contract Number:
SC0015771
Type / Phase:
SBIR
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 36 MATERIALS SCIENCE; I-129; iodide; iodate; Tc-99; radionuclide; Hanford; Savannah River; sorbent; iodine; adsorption capacity; ground water; subsurface water

Citation Formats

Jain, Mohit. A Highly Selective and High Efficiency Smart Sorbent for Iodine-129. United States: N. p., 2017. Web.
Jain, Mohit. A Highly Selective and High Efficiency Smart Sorbent for Iodine-129. United States.
Jain, Mohit. Tue . "A Highly Selective and High Efficiency Smart Sorbent for Iodine-129". United States. doi:.
@article{osti_1349642,
title = {A Highly Selective and High Efficiency Smart Sorbent for Iodine-129},
author = {Jain, Mohit},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Apr 04 00:00:00 EDT 2017},
month = {Tue Apr 04 00:00:00 EDT 2017}
}

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  • The nitrate anion is the predominant constituent in all high-level nuclear wastes. Formic acid reacts with the nitrate anion to yield noncondensable, inert gases (N/sub 2/ or N/sub 2/O), which can be scrubbed free of /sup 106/Ru, /sup 129/I, and /sup 99/Tc radioactivities prior to elimination from the plant by passing through HEPA filters. Treatment of a high-level authentic radioactive waste with two moles of formic acid per mole of nitrate anion leads to a low RuO/sub 4/ volatility of about 0.1%, which can be reduced to an even lower level of 0.007% on adding a 15% excess of formicmore » acid. Without pretreatment of the nitrate waste with formic acid, a high RuO/sub 4/ volatility of approx. 35% is observed on calcining a 4.0 N HNO/sub 3/ solution in quartz equipment at 350/sup 0/C. The RuO/sub 4/ volatility falls to approx. 1.0% on decreasing the initial HNO/sub 3/ concentration to 1.0 N or lower. It is postulated that thermal denitration of a highly nitrated ruthenium complex leads to the formation of volatile RuO/sub 4/, while decarboxylation of a ruthenium-formate complex leads to the formation of nonvolatile RuO/sub 2/. Wet scrubbing with water is used to remove RuO/sub 4/ from the off-gas stream. In all glass equipment, small amounts of particulate RuO/sub 2/ are formed in the gas phase by decomposition of RuO/sub 4/. The /sup 99/Tc volatility was found to vary from 0.2 to 1.4% on calcining HNO/sub 3/ and HCOOH (formic acid) solutions over the temperature range of 250 to 600/sup 0/C. These unexpectedly low volatilities of /sup 99/Tc are correlated to the high thermal stability limits of various metal pertechnetates and technetates. Iodine volatilities were high, varying from a low of 30% at 350/sup 0/C to a high of 97% at 650/sup 0/C. It is concluded that with a proper selection of pretreatment and operating conditions the /sup 106/Ru and /sup 99/Tc activities can be retained in the calcined solid with recycle of the wet scrubbing solution.« less
  • A dynamic linear compartment model of the global iodine cycle has been developed for the purpose of estimating long-term doses and dose commitments to the world population from releases of /sup 129/I to the environment. The environmental compartments assumed in the model comprise the atmosphere, hydrosphere, lithosphere, and terrestrial biosphere. The global transport of iodine is described by means of time-invariant fractional transfer rates between the environmental compartments. The fractional transfer rates for /sup 129/I are determined primarily from available data on compartment inventories and fluxes for naturally occurring stable iodine and from data on the global hydrologic cycle. Themore » dose to the world population is estimated from the calculated compartment inventories of /sup 129/I, the known compartment inventories of stable iodine, a pathway analysis of the intake of iodine by a reference individual, dose conversion factors for inhalation and ingestion, and an estimate of the world population. For an assumed constant population of 12.21 billion beyond the year 2075, the estimated population dose commitment is 2 x 10/sup 5/ man-rem/Ci. The sensitivity of the calculated doses to variations in some of the parameters in the model for the global iodine cycle is investigated. A computer code written to calculate global compartment inventories and dose rates and population doses is described and documented.« less
  • Nuclear fission results in the production of fission products (FPs) and activation products that increasingly interfere with the fission process as their concentrations increase. Some of these fission and activation products tend to evolve in gaseous species during used nuclear fuel reprocessing. Analyses have shown that I129, due to its radioactivity, high potential mobility in the environment, and high longevity (half life of 15.7 million years), can require control efficiencies of up to 1,000x or higher to meet regulatory emission limits. Deep-bed iodine sorption testing has been done to evaluate the performance of solid sorbents for capturing iodine in off-gasmore » streams from nuclear fuel reprocessing plants. The objectives of the FY 2011 deep bed iodine sorbent testing are: (1) Evaluate sorbents for iodine capture under various conditions of gas compositions and operating temperature (determine sorption efficiencies, capacities, and mass transfer zone depths); and (2) Generate data for dynamic iodine sorption modeling. Three tests performed this fiscal year on silver zeolite light phase (AgZ-LP) sorbent are reported here. Additional tests are still in progress and can be reported in a revision of this report or a future report. Testing was somewhat delayed and limited this year due to initial activities to address some questions of prior testing, and due to a period of maintenance for the on-line GC. Each test consisted of (a) flowing a synthetic blend of gases designed to be similar to an aqueous dissolver off-gas stream over the sorbent contained in three separate bed segments in series, (b) measuring each bed inlet and outlet gas concentrations of iodine and methyl iodide (the two surrogates of iodine gas species considered most representative of iodine species expected in dissolver off-gas), (c) operating for a long enough time to achieve breakthrough of the iodine species from at least one (preferably the first two) bed segments, and (d) post-test purging with pure N2 to drive loosely or physisorbed iodine species off of the sorbent. Post-test calculations determine the control efficiencies for each bed, iodine loadings on the sorbent, and mass transfer zone depths. Portions of the iodine-laden sorbent from the first bed of two of the tests have been shipped to SNL for waste form studies. Over the past three years, we have explored a full range of inlet iodine and methyl iodide concentrations ranging from {approx}100 ppb to {approx}100 ppm levels, and shown adequate control efficiencies within a bed depth as shallow as 2 inches for lower concentrations and 4 inches for higher concentrations, for the AgZ-type sorbents. We are now performing a limited number of tests in the NC-77 sorbent from SNL. Then we plan to continue to (a) fill in data gaps needed for isotherms and dynamic sorbent modeling, and (b) test the performance of additional sorbents under development.« less