A Literature Survey to Identify Potentially Volatile Iodine-Bearing Species Present in Off-Gas Streams

Bruffey, Stephanie H.; Spencer, Barry B.; Strachan, D. M.; Jubin, Robert Thomas; Soelberg, Nick; Riley, Brian J.

doi:10.2172/1235202

Cited by 22 publications

(36 citation statements)

References 65 publications

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“…The VOG will most likely contain iodine at ppb concentrations. The VOG is also the stream most likely to contain organic iodides, which have been considered more difficult to remove (or more penetrating) than I2 when using with traditional sorbents (Bruffey et al 2015a).…”

Section: Introductionmentioning

confidence: 99%

Extended Elemental Iodine Adsorption by AgZ under Prototypical Vessel Off-Gas Conditions

Jubin

Jordan

Bruffey

2018

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US regulations will require the removal of 129 I from the off-gas streams of any used nuclear fuel (UNF) reprocessing plant prior to discharge of the off-gas to the environment. Multiple off-gas streams within a UNF reprocessing plant combine prior to environmental release, and each of these streams contains some amount of iodine. For an aqueous UNF reprocessing plant, these streams include the dissolver off-gas (DOG), the cell off-gas (COG), the vessel off-gas (VOG), the waste off-gas (WOG), and the shear off-gas (SOG). To achieve regulatory compliance, treatment of multiple off-gas streams within the plant must be performed. Of these remaining streams, the VOG is expected to be one of the major contributors to the balance of the residual iodine releases. The VOG will most likely contain iodine at parts-per-billion (ppb * ) concentrations.Preliminary studies were completed on the adsorption of I2 onto hydrogen-reduced silver mordenite (Ag 0 Z) from prototypical VOG streams. The previous tests were of relatively short duration (3-4 months) and loaded the sorbent to far less than its expected saturation loading. As a result, little to no information could be extracted regarding the length of the mass transfer zone or the long-term concurrent sorbent aging and loading behavior. The test reported here is the first part of a series of long-duration tests designed to identify the saturation loading of the sorbent under VOG conditions and, as a part of this, to determine the length of the mass transfer zone.This test represents the longest extended VOG test conducted to date by this program. This test ran 38 weeks and achieved iodine loadings of ~40 mg I/g sorbent. The iodine mass transfer zone penetrated at least 10.5 cm into the sorbent beds. There was no indication of sorbent saturation. The mass balance for iodine closed within 2%, which is within the expected combined uncertainty.While this test did not achieve saturation of any portion of the test beds, the data does provide significant information that can be used to extrapolate a potential maximum length of the mass transfer zone under VOG conditions. Under the conditions used in this test, the mass transfer zone could be on the order of 21 cm.This test also provides the basis for the design of the next series of extended VOG tests. Future tests to examine the validity of the extrapolation to a saturated VOG sorbent bed should be designed to run up to ~4.9 years, assuming a 50 ppb I2 feed gas, and have a bed length greater than 32 cm. Future efforts regarding the adsorption of iodine from prototypical VOG streams by silver-based sorbents will attempt to extend the test duration to (1) determine if the slope of the iodine loading front remains constant; (2) determine the saturation concentration reflecting aging in situ; and (3) compare the extended loading behavior for organic iodides. Additionally, the adsorption of different iodine species, such as C12H25I, will be studied. Other variables that merit examination are the gas velocity of the test and the depend...

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Section: Introductionmentioning

confidence: 99%

Extended Elemental Iodine Adsorption by AgZ under Prototypical Vessel Off-Gas Conditions

Jubin

Jordan

Bruffey

2018

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“…Volatile chloride or fluoride products can also be formed with uranium, some transuranics, and fission products (Riley et al, 2018a). Radionuclides that can be present in the gas phase and are of most concern include 3 H, 14 C, 85 Kr, and 129 I (Bruffey et al, 2015;Riley et al, 2016). Iodine, for example, can form many species in molten salt systems including I  , and I 2 , (Bruffey et al, 2015) and mixed halide species.…”

Section: Molecular Analysis Of Gas-phase Speciesmentioning

confidence: 99%

Molten Salt Reactor Engineering Study for Off-Gas Management

McFarlane

Riley

Holcomb

et al. 2020

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“…A recent report by Bruffey et al (2015) points out that the study of inorganic iodide in off-gas systems has been almost exclusively limited to I 2 , and the focus of organic iodide studies has been CH 3 I. This report specially focused on those iodine species that have the potential to be poorly sequestered with traditional capture methodologies.…”

Section: Figuresmentioning

confidence: 99%

A Brief User's Guide to the Excel<sup>®</sup> -Based DF Calculator

Jubin¹

2016

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To understand the importance of capturing penetrating forms of iodine as well as the other volatile radionuclides, a calculation tool was developed in the form of an Excel ® spreadsheet to estimate the overall plant decontamination factor (DF). The tool requires the user to estimate splits of the volatile radionuclides within the major portions of the reprocessing plant, speciation of iodine and individual DFs for each off-gas stream within the Used Nuclear Fuel reprocessing plant. The impact to the overall plant DF for each volatile radionuclide is then calculated by the tool based on the specific user choices. The Excel ® spreadsheet tracks both elemental and penetrating forms of iodine separately and allows changes in the speciation of iodine at each processing step. It also tracks 3 H, 14 C and 85 Kr. This document provides a basic user's guide to the manipulation of this tool. The DF Calculator uses two types of building blocks. The first is input blocks in which the user can insert information on the feed to the system, splits in various unit operations, and capture efficiencies for each stream of interest. The second class of blocks is the stream composition blocks or results blocks. Based on the user input, the quantity of each species reaching the stack is calculated, and an overall plant DF computed. Graphic output is also provided for each species in terms of the contribution of each of the five off-gas streams that contribute to the overall plant gaseous emissions.

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A Literature Survey to Identify Potentially Volatile Iodine-Bearing Species Present in Off-Gas Streams

Cited by 22 publications

References 65 publications

Extended Elemental Iodine Adsorption by AgZ under Prototypical Vessel Off-Gas Conditions

Extended Elemental Iodine Adsorption by AgZ under Prototypical Vessel Off-Gas Conditions

Molten Salt Reactor Engineering Study for Off-Gas Management

A Brief User's Guide to the Excel<sup>®</sup> -Based DF Calculator

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