Performance of Silver-Exchanged Mordenite and Silver-Functionalized Silica-Aerogel Under Vessel Off-gas Conditions

Jubin, Robert Thomas; Bruffey, Stephanie H.; Jordan, Jacob A.

doi:10.2172/1427666

Cited by 20 publications

(53 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Comparison of Extended and Accelerated VOG Tests 29 May 2020 3 subsamples that represented 2-3% of a large deep bed and ~10% for subsamples that represent significantly larger fractions of thin beds (Jubin et al 2017). The error associated with NAA is presented in the figures of this report, but the effects of sample heterogeneity should be also be considered during data analysis.…”

Section: Methodsmentioning

confidence: 97%

“…After these initial tests, more expansive experimentation evaluated the effects of concentration on CH 3 I adsorption by both AgZ and silver-functionalized silica aerogel (AgAero), an alternative silver-based iodine sorbent in early development (Jubin et al 2017). Concentrations from 40 to 1000 ppb v were evaluated and it was found that the adsorption profile in the bed was unchanged over that concentration range.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Comparison of Extended and Accelerated VOG Tests

Greaney

Bruffey

2020

View full text Add to dashboard Cite

The reprocessing of used nuclear fuel would release volatile radionuclides into the off-gas streams of a processing plant, including 129 I. The dissolver off-gas and more dilute vessel off-gas streams (VOG) must both be targeted when mitigating 129 I environmental release because each contains some amount of iodine. Iodine-129 will likely be found as elemental iodine (I 2) and methyl iodide (CH 3 I) in these off-gas streams. Reduced silver-exchanged mordenite (AgZ or Ag 0 Z) has been investigated as a potential sorbent for iodine abatement and is studied here under prototypic VOG conditions. Because of the relatively low iodine abundance and high flow rates of the VOG, total iodine concentrations are expected to be in the parts per billion range. Thus, VOG experiments need to run for extended durations at low concentrations to reach sorbent saturation. Because the sorbent will be exposed to oxidizing gas streams for extended periods of time, aging effects and sorbent degradation need to be considered when designing a sorbent-based abatement system. Three sets of experiments were performed with the aim of determining how the adsorption of iodine by AgZ is affected by differing test durations and gas compositions. The first tested the capacity of sorbent aged for 8 months under a humid air stream. The second tested differences in sorbent capacity and mass transfer zone (MTZ) length during high-concentration (1200 ppb v) CH 3 I loading in a humid nitrogen gas (N 2) stream and a humid air gas stream over 28 days. The third tested sorbent capacity and MTZ length during low concentration (< 200 ppb v) CH 3 I and I 2 loading in a humid air stream over 9 months. The results of these tests suggest that AgZ capacity drops by ~50% after 1 month of aging, by ~60% after 2 months of aging, and then does not continue to decrease significantly at up to 8 months of aging. One-month aging tests that compared N 2 and air as the gas stream diluent resulted in similar maximum loading capacities and overall loading curves, indicating that the effects of aging cannot be mitigated by avoiding air as the balance gas. The 9-month extended VOG tests did not result in clear sorbent saturation at the inlet, but it can be inferred using an assumption of a maximum capacity of 45 mg I/g AgZ. Applying this assumption, then the MTZ of CH 3 I is 12.8 cm, and the MTZ of I 2 is 12.4 cm. These results are similar to previous tests. Comparisons to tests completed at Idaho National Laboratory suggest that the CH 3 I MTZ may be dependent on concentration. Future work should re-evaluate the design of the VOG iodine capture system with this updated data and should seek to understand fundamental characteristics of CH 3 I adsorption by AgZ, such as the effect of concentration, gas velocity, and gas composition.

show abstract

Section: Methodsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Comparison of Extended and Accelerated VOG Tests

Greaney

Bruffey

2020

View full text Add to dashboard Cite

show abstract

“…In a subsequent report (Jubin et al 2013), the role of off-gas pathways was examined since the gaseous radionuclides can partition to various different reprocessing off-gas streams. Based on this report and subsequent analysis (Jubin, et al 2015), the DF for 129 I could be 1000 to 3000. The required DF for H could be as high as 200, depending on the age of the fuel processed.…”

Section: Figuresmentioning

confidence: 93%

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

Jubin¹

2016

View full text Add to dashboard Cite

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.

show abstract

“…Multiple silver containing materials, including macroreticular resins, silver impregnated alumina, silver exchanged faujasite, hydrogen‐reduced silver exchanged mordenite (Ag 0 Z), and reduced silver‐functionalized silica aerogel (Ag 0 ‐Aerogel), have been developed and studied for I 2 and organic iodides adsorption 4,10,14‐18 . The reason for selecting silver‐containing materials over traditional liquid scrubbing methods is concluded to be stronger AgI bond and solid form, therefore, higher removal efficiency and lower operation cost 4,19‐22 .…”

Section: Introductionmentioning

confidence: 99%

Adsorption of methyl iodide on reduced silver‐functionalized silica aerogel: Kinetics and modeling

et al. 2021

View full text Add to dashboard Cite

The low concentration methyl iodide (CH3I) adsorption process on reduced silver‐functionalized silica aerogel (Ag0‐Aerogel) was studied. The kinetic data were acquired using a continuous flow adsorption system. Because the corresponding physical process was observed, the shrinking core model (SCM) was modified and applied. An average CH3I pore diffusivity was calculated, the CH3I‐Ag0‐Aerogel reaction was identified as a 1.40 order reaction instead of first order reaction, and the nth order reaction rate constant was determined. This modified SCM significantly increases the accuracy of adsorption behavior prediction at low adsorbate concentration. Modeling results indicate that the overall adsorption process is controlled by the pore diffusion. However, at low adsorbate concentration (ppbv level), the CH3I adsorption is limited to the surface reaction due to the low uptake rate in a predictable time period.

show abstract

Performance of Silver-Exchanged Mordenite and Silver-Functionalized Silica-Aerogel Under Vessel Off-gas Conditions

Cited by 20 publications

References 3 publications

Comparison of Extended and Accelerated VOG Tests

Comparison of Extended and Accelerated VOG Tests

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

Adsorption of methyl iodide on reduced silver‐functionalized silica aerogel: Kinetics and modeling

Contact Info

Product

Resources

About