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Title: Flowsheet report for baseline actinide blanket processing for accelerator transmutation of waste

Abstract

We provide a flowsheet analysis of the chemical processing of actinide and fission product materials form the actinide blanket of an accelerator-based transmutation concept. An initial liquid ion exchange step is employed to recover unburned plutonium and neptunium, so that it can be returned quickly to the transmitter. The remaining materials, consisting of fission products and trivalent actinides (americium, curium), is processed after a cooling period. A reverse Talspeak process is employed to separate these trivalent actinides from lanthanides and other fission products.

Authors:
Publication Date:
Research Org.:
Los Alamos National Lab., NM (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10176370
Report Number(s):
LA-UR-92-1241
ON: DE93000343
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 8 Apr 1992
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; RADIOACTIVE WASTE PROCESSING; TRANSMUTATION; FLOWSHEETS; ACTINIDES; FISSION PRODUCTS; ION EXCHANGE; TALSPEAK PROCESS; 052001; WASTE PROCESSING

Citation Formats

Walker, R.B.. Flowsheet report for baseline actinide blanket processing for accelerator transmutation of waste. United States: N. p., 1992. Web. doi:10.2172/10176370.
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Walker, R.B.. Flowsheet report for baseline actinide blanket processing for accelerator transmutation of waste. United States. doi:10.2172/10176370.
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Walker, R.B.. Wed . "Flowsheet report for baseline actinide blanket processing for accelerator transmutation of waste". United States. doi:10.2172/10176370. https://www.osti.gov/servlets/purl/10176370.
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@article{osti_10176370,
title = {Flowsheet report for baseline actinide blanket processing for accelerator transmutation of waste},
author = {Walker, R.B.},
abstractNote = {We provide a flowsheet analysis of the chemical processing of actinide and fission product materials form the actinide blanket of an accelerator-based transmutation concept. An initial liquid ion exchange step is employed to recover unburned plutonium and neptunium, so that it can be returned quickly to the transmitter. The remaining materials, consisting of fission products and trivalent actinides (americium, curium), is processed after a cooling period. A reverse Talspeak process is employed to separate these trivalent actinides from lanthanides and other fission products.},
doi = {10.2172/10176370},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Apr 08 00:00:00 EDT 1992},
month = {Wed Apr 08 00:00:00 EDT 1992}
}
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Technical Report:
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DOI:  10.2172/10176370
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  • We provide a flowsheet analysis of the chemical processing of actinide and fission product materials form the actinide blanket of an accelerator-based transmutation concept. An initial liquid ion exchange step is employed to recover unburned plutonium and neptunium, so that it can be returned quickly to the transmitter. The remaining materials, consisting of fission products and trivalent actinides (americium, curium), is processed after a cooling period. A reverse Talspeak process is employed to separate these trivalent actinides from lanthanides and other fission products.

  • ; ; ; ...
    An accelerator-driven subcritical nuclear system is briefly described that transmutes actinides and selected long-lived fission products. An application of this accelerator transmutation of nuclear waste (ATW) concept to spent fuel from a commercial nuclear power plant is presented as an example. The emphasis here is on a possible aqueous processing flowsheet to separate the actinides and selected long-lived fission products from the remaining fission products within the transmutation system. In the proposed system the actinides circulate through the thermal neutron flux as a slurry of oxide particles in heavy water in two loops with different average residence times: one loopmore » for neptunium and plutonium and one for americium and curium. Material from the Np/Pu loop is processed with a short cooling time (5-10 days) because of the need to keep the total actinide inventory, low for this particular ATW application. The high radiation and thermal load from the irradiated material places severe constraints on the separation processes that can be used. The oxide particles are dissolved in nitric acid and a quarternary, ammonium anion exchanger is used to extract neptunium, plutonium, technetium, and palladium. After further cooling (about 90 days), the Am, Cm and higher actinides are extracted using a TALSPEAK-type process. The proposed operations were chosen because they have been successfully tested for processing high-level radioactive fuels or wastes in gram to kilogram quantities.« less

  • ; ;
    At Los Alamos, an innovative approach to transmuting long-lived radioactive waste is under investigation. The concept is to use a linear proton accelerator coupled to a solid target to produce an intense neutron flux. The intense stream of neutrons can then be used to fission or transmute long-lived radionuclides to either stable or shorter-lived isotopes. For the program to be successful, robust chemical separations with high efficiencies (>10{sup 5}) are required. The actual mission, either defense or commercial, will determine what suite of unit operations will be needed. If the mission is to process commercial spent fuel, there are severalmore » options available for feed preparation and blanket processing. The baseline option would be an improved PUREX system with the main alternative being the current ATW actinide blanket processing flowsheet. {sup 99}Tc and {sup 129}I are more likely to reach the biosphere than the actinides. Many models have been developed for predicting how the radionuclides will behave in a repository over long time periods. The general conclusion is that the actinides will be sorbed by the soil. Therefore, over a long time period, e.g., a million years their hazard will be lessened because of radioactive decay and dispersion. However, some of the long-lived fission products are not sorbed and could potentially reach the environment over a few thousand year period. Hence, they could present a significant safety hazard. Because of limited resources, most of the priority has been focused on the actinide and technetium blanket assemblies.« less

  • ; ;
    At Los Alamos, an innovative approach to transmuting long-lived radioactive waste is under investigation. The concept is to use a linear proton accelerator coupled to a solid target to produce an intense neutron flux. The intense stream of neutrons can then be used to fission or transmute long-lived radionuclides to either stable or shorter-lived isotopes. For the program to be successful, robust chemical separations with high efficiencies (>10{sup 5}) are required. The actual mission, either defense or commercial, will determine what suite of unit operations will be needed. If the mission is to process commercial spent fuel, there are severalmore » options available for feed preparation and blanket processing. The baseline option would be an improved PUREX system with the main alternative being the current ATW actinide blanket processing flowsheet. {sup 99}Tc and {sup 129}I are more likely to reach the biosphere than the actinides. Many models have been developed for predicting how the radionuclides will behave in a repository over long time periods. The general conclusion is that the actinides will be sorbed by the soil. Therefore, over a long time period, e.g., a million years their hazard will be lessened because of radioactive decay and dispersion. However, some of the long-lived fission products are not sorbed and could potentially reach the environment over a few thousand year period. Hence, they could present a significant safety hazard. Because of limited resources, most of the priority has been focused on the actinide and technetium blanket assemblies.« less

  • A detailed assessment of the target-blanket performance of an Accelerator Transmutation of Waste (ATW) system has been performed for a preconceptual, aqueous-based reference design. The performance analyses required that detailed neutronics calculations for the target and blanket systems to be coupled with blanket processing. This coupling is at a complex interface, and both neutronic and processing requirements strongly impact system performance. The neutronics analyses have integrated the goals of (1) high neutron source strength in the target region (2) high neutron multiplication and efficient neutron economy in the blanket region, and (3) large fission/transmutation rates per unit inventory in themore » blanket. The neutronic calculations have been fully coupled with both time-dependent and steady-state processing using a depletion code. Depletion calculations are critical for determining blanket design and performance. Isotopic concentrations in the various subsystems effect both the transmutation rates as well as the chemical processing required by the system. In the blanket, accurate isotopic data are required in order to predict not only equilibrium performance, but also transient system performance during startup and pre-equilibrium stages. The depletion analysis also allowed the calculation of blanket inventories and concentrations of the transmutation products. This is essential to determine parasitic absorption, which strongly effects blanket multiplication and neutron economy requirements. It was found that the parasitic adsorption is dependent on both flux level and processing time. Isotopic and elemental concentrations in the various blanket/processing loops and subsystems were also calculated.« less