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Title: TC-99 Decontaminant from heat treated gaseous diffusion membrane -Phase I, Part B

Abstract

Uranium gaseous diffusion cascades represent a significant environmental challenge to dismantle, containerize and dispose as low-level radioactive waste. Baseline technologies rely on manual manipulations involving direct access to technetium-contaminated piping and materials. There is a potential to utilize novel decontamination technologies to remove the technetium and allow for on-site disposal of the very large uranium converters. Technetium entered these gaseous diffusion cascades as a hexafluoride complex in the same fashion as uranium. Technetium, as the isotope Tc-99, is an impurity that follows uranium in the first cycle of the Plutonium and Uranium Extraction (PUREX) process. The technetium speciation or exact form in the gaseous diffusion cascades is not well defined. Several forms of Tc-99 compounds, mostly the fluorinated technetium compounds with varying degrees of volatility have been speculated by the scientific community to be present in these cascades. Therefore, there may be a possibility of using thermal or leaching desorption, which is independent of the technetium oxidation states, to perform an insitu removal of the technetium as a volatile species and trap the radionuclide on sorbent traps which could be disposed as low-level waste. Based on the positive results of the first part of this work1 the use of steammore » as a thermal decontamination agent was further explored with a second piece of used barrier material from a different location. This new series of tests included exposing more of the material surface to the flow of high temperature steam through the change in the reactor design, subjecting it to alternating periods of stream and vacuum, as well as determining if a lower temperature steam, i.e., 121°C (250°F) would be effective, too. Along with these methods, one other simpler method involving the leaching of the Tc-99 contaminated barrier material with a 1.0 M aqueous solution of ammonium carbonate, with and without sonication, was evaluated.« less

Authors:
 [1];  [1];  [1];  [1]
  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:
1409185
Report Number(s):
SRNL-STI-2017-00380
TRN: US1800038
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; LOW-LEVEL RADIOACTIVE WASTES; TECHNETIUM; URANIUM; GASEOUS DIFFUSION; PLUTONIUM; PUREX PROCESS

Citation Formats

Oji, L., Restivo, M., Duignan, M., and Wilmarth, B. TC-99 Decontaminant from heat treated gaseous diffusion membrane -Phase I, Part B. United States: N. p., 2017. Web. doi:10.2172/1409185.
Oji, L., Restivo, M., Duignan, M., & Wilmarth, B. TC-99 Decontaminant from heat treated gaseous diffusion membrane -Phase I, Part B. United States. doi:10.2172/1409185.
Oji, L., Restivo, M., Duignan, M., and Wilmarth, B. 2017. "TC-99 Decontaminant from heat treated gaseous diffusion membrane -Phase I, Part B". United States. doi:10.2172/1409185. https://www.osti.gov/servlets/purl/1409185.
@article{osti_1409185,
title = {TC-99 Decontaminant from heat treated gaseous diffusion membrane -Phase I, Part B},
author = {Oji, L. and Restivo, M. and Duignan, M. and Wilmarth, B.},
abstractNote = {Uranium gaseous diffusion cascades represent a significant environmental challenge to dismantle, containerize and dispose as low-level radioactive waste. Baseline technologies rely on manual manipulations involving direct access to technetium-contaminated piping and materials. There is a potential to utilize novel decontamination technologies to remove the technetium and allow for on-site disposal of the very large uranium converters. Technetium entered these gaseous diffusion cascades as a hexafluoride complex in the same fashion as uranium. Technetium, as the isotope Tc-99, is an impurity that follows uranium in the first cycle of the Plutonium and Uranium Extraction (PUREX) process. The technetium speciation or exact form in the gaseous diffusion cascades is not well defined. Several forms of Tc-99 compounds, mostly the fluorinated technetium compounds with varying degrees of volatility have been speculated by the scientific community to be present in these cascades. Therefore, there may be a possibility of using thermal or leaching desorption, which is independent of the technetium oxidation states, to perform an insitu removal of the technetium as a volatile species and trap the radionuclide on sorbent traps which could be disposed as low-level waste. Based on the positive results of the first part of this work1 the use of steam as a thermal decontamination agent was further explored with a second piece of used barrier material from a different location. This new series of tests included exposing more of the material surface to the flow of high temperature steam through the change in the reactor design, subjecting it to alternating periods of stream and vacuum, as well as determining if a lower temperature steam, i.e., 121°C (250°F) would be effective, too. Along with these methods, one other simpler method involving the leaching of the Tc-99 contaminated barrier material with a 1.0 M aqueous solution of ammonium carbonate, with and without sonication, was evaluated.},
doi = {10.2172/1409185},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month =
}

Technical Report:

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  • Uranium gaseous diffusion cascades represent a significant environmental challenge to dismantle, containerize and dispose as low-level radioactive waste. Baseline technologies rely on manual manipulations involving direct access to technetium-contaminated piping and materials. There is a potential to utilize novel thermal decontamination technologies to remove the technetium and allow for on-site disposal of the very large uranium converters. Technetium entered these gaseous diffusion cascades as a hexafluoride complex in the same fashion as uranium. Technetium, as the isotope Tc-99, is an impurity that follows uranium in the first cycle of the Plutonium and Uranium Extraction (PUREX) process. The technetium speciation ormore » exact form in the gas diffusion cascades is not well defined. Several forms of Tc-99 compounds, mostly the fluorinated technetium compounds with varying degrees of volatility have been speculated by the scientific community to be present in these cascades. Therefore, there may be a possibility of using thermal desorption, which is independent of the technetium oxidation states, to perform an in situ removal of the technetium as a volatile species and trap the radionuclide on sorbent traps which could be disposed as low-level waste.« less
  • The objectives of the study reported were to: identify specific uses for the waste heat released at the Portsmouth Gaseous Diffusion Plant (GDP), such as used in the process industries, and to establish the technical feasibility of such uses; evaluate the economic feasibility of the uses found to be technically feasible; develop a waste heat system of multiple feasible uses compatible with the characteristics of the region in the vicinity of the Portsmouth GDP; and develop a plan and an organization which would be used to implement the construction of the proposed waste heat system of uses. A regional descriptionmore » is followed by the criteria used for the studies and the selection method used to determine the most likely applications. A detailed treatment of conveying the heat from the GDP to points of use is given. Seven product-oriented uses are analyzed in some detail. Special consideration is given for the technical and economic feasibility of space heating and electric power generation. The merits of stored thermal energy as a backup for the waste heat source are examined. Temperature augmentation of waste heat water is discussed. Potential direct environmental impacts from the construction and operation of a waste heat utilization system are reviewed, followed by analysis of the social, economic, and environmental impacts of waste heat development on the local communities. Organizations for management of waste heat projects and associated community growth are explored. (LEW)« less
  • Details are given of an overall proposed waste heat system to serve three selected applications. The organization and the steps needed to implement a waste heat system are discussed. Appended are discussions of the reasons why some potential applications were rejected after only partial analysis, documentation of soils and water studies, additional details on electric power generation and thermal energy storage, and growth management models as well as supporting reports by consultants. (LEW)
  • An engineering feasibility study and cost estimate were carried for a Thermal Utility Plant (TUP) utilizing waste heat from the Department of Energy (DOE) Uranium Enrichment Gaseous Diffusion Plant (GDP) at Paducah, Kentucky. The Thermal Utility Plant studied herein uses heat pump technology to recover available waste heat from the GDP cooling water stream in the form of subatmospheric water vapor and compresses it to usable process steam pressures. The steam from the TUP would than be utilized in various process applications at an alcohol facility which is proposed to be located adjacent to the TUP site.