Fission Product Volatility and Off-Gas Systems for Molten Salt Reactors

Joanna Mcfarlane, N. Dianne Bull Ezell, Guillermo D. Del Cul, David Eugene Holcomb, Kristian Myhre, Amanda Lines, Sam Bryan, Heather M. Felmy, Brian J. Riley, Austin Chapel

Research output: Book/ReportCommissioned report

Abstract

The overall objective of the Department of Energy investigation into off-gas technology for molten salt reactors (MSR)s is to develop a list of functional requirements for an effective and reliable system. In collaboration with other elements of the Advanced Reactor Campaign (denoted in italics), the off-gas work package will address the following questions: 1. What is the composition of the gas stream going to the off-gas system (chemistry and source term work package)? 2. What is the function of each off-gas treatment component, and how do they work? How efficient are they at removing or delaying fission and activation products? 3. What are the maintenance requirements of the off-gas system? 4. Is the system able to effectively detect and respond to off-normal events (off-gas, source term, and simulation work packages)? 5. What measurement capabilities are possible now? What are the gaps? The objective of the off-gas project in fiscal year 2019 was to address the second, fourth, and fifth questions above. Thus, project has proceeded along two fronts: one focused on scrubber development at Oak Ridge National Laboratory and the other focused on spectroscopic detection of simulant fission product iodine at Pacific Northwest National Laboratory. A molten hydroxide scrubber was proposed for removal of both acidic gases, entrained mists, and particulates from a sparged molten salt off-gas. Hydroxide solutions are well known for their scrubbing ability and have been used in the off-gas systems of salt processing facilities. For the current project, a NaOH–KOH eutectic is being evaluated as a gettering medium. A laboratory-scale prototype glass scrubber was designed and built for the removal of aerosol simulants. The glass allows visualization of the scrubber operation, which is important for designing the stainless-steel housing for the NaOH–KOH eutectic. In parallel, Pacific Northwest National Laboratory has been developing optical sensors for detecting fission products and aerosol or mist species that could be entrained in the off-gas flow of an MSR. Efforts include Raman spectroscopy to identify and quantify iodine species such as I2 and ICl and laser-induced breakdown spectroscopy and laser-induced fluorescence for mists. Next year, these optical methods will be added to the hydroxide scrubber instrumentation to determine its effectiveness against airborne vapors and mists of concern.
Original languageEnglish
Place of PublicationUnited States
DOIs
StatePublished - 2019

Keywords

  • 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
  • 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

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