Molten Salt Reactor Engineering Study for Off-Gas Management

McFarlane, Joanna; Riley, Brian J.; Holcomb, David Eugene; Lines, Amanda M.; Andrews, Hunter; Bryan, Sam; Chapel, A. Shay; Ezell, N. Dianne Bull; Felmy, Heather M.; Greenwood, Michael S.; Humrickhouse, Paul W.; Myhre, Kristian

doi:10.2172/1649021

Cited by 7 publications

(17 citation statements)

References 144 publications

(200 reference statements)

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“…The literature suggests that iodine could take on a variety of species within the molten eutectic. , In the molten hydroxide system, iodate is not as favored as it is an aqueous species. However, operating molten salt scrubbers will likely have some level of moisture ingress during operation or moisture production from reaction of certain species as shown in Scheme .…”

Section: Resultsmentioning

confidence: 99%

“…Several off-gas treatment systems are being developed. These systems include solid sorbents such as silver zeolites, silver mordenite, silver-functionalized silica aerogels, silver-loaded aluminosilicate aerogels and xerogels, , sulfur aerogels, graphene aerogels, metal–organic frameworks, and molten salt liquid scrubbers. , More research is required to characterize each scrubber’s performance in simulated and deployed treatment systems . Such a characterization can be provided by online monitoring technologies.…”

Section: Introductionmentioning

confidence: 99%

“…Hydroxide-based scrubbers have been proposed as a method to capture wastes in the form of particulates, aerosols, mists, reactive gases, and residual gaseous halides. , Molten hydroxide scrubbers operate at higher temperatures compared to aqueous scrubbers, and they have been suggested to have a higher efficiency than an aqueous-based caustic scrubber . This is due to the higher concentration of hydroxides available to react with incoming vapors compared to an aqueous-based caustic scrubber.…”

Section: Introductionmentioning

confidence: 99%

“…Scheme 1. Proposed Reactions of Gaseous Halides, Hydrogen Halides, and Organo-Halides with Molten Sodium Hydroxide as Described in the Literature18,21,23,28…”

mentioning

confidence: 99%

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Iodine and Carbonate Species Monitoring in Molten NaOH–KOH Eutectic Scrubber via Dual-Phase In Situ Raman Spectroscopy

et al. 2022

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Molten hydroxide scrubbing of off-gas vapors is a potential process to improve safety during the operation of generation IV molten salt nuclear reactors (MSRs). MSRs produce off-gases that can be vented by the reactor core and treated via off-gas scrubbers. Molten hydroxide scrubbers focus on capturing volatile iodine radionuclides, and they can also be used to capture aerosols and particulates and to neutralize acidic species. The performance of these scrubbers depends on the chemical interactions of the scrubbing medium with the off-gas species. Knowledge of the concentration and speciation of scrubbed or target species, as well as process and environmental interferents, can enable advanced operation of MSR off-gas treatment systems. Optical online monitoring is an excellent technology to provide this information in real time, while limiting the need for operators to interact with radioactive samples through hands-on interrogation. Raman spectroscopy can provide crucial chemical information on the state of the molten eutectic during treatment in the molten phase, as well as the gas phase. In this work, Raman spectroscopy is used to detect iodine species, specifically iodate, in the molten phase of a NaOH−KOH eutectic and to construct a calibration curve of the Raman signal of those species. Additionally, a carbonate interferent is followed from the gas phase to the liquid phase as a basis for reaching a Raman-aided mass balance of the molten hydroxide eutectic scrubber system.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Scheme 1. Proposed Reactions of Gaseous Halides, Hydrogen Halides, and Organo-Halides with Molten Sodium Hydroxide as Described in the Literature18,21,23,28…”

mentioning

confidence: 99%

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Iodine and Carbonate Species Monitoring in Molten NaOH–KOH Eutectic Scrubber via Dual-Phase In Situ Raman Spectroscopy

et al. 2022

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“…Thermochemical properties, which are the principal focus of the referenced study, include the chemical state, vapor pressures, and radionuclide mass transport, leading to the radioactive source term during operation and as a result of accidents. Off-gas can be a key source of a radioactive material release for MSRs because the system transports radioactive material released from the salt external to the reactor vessel [27,28]. Thermochemistry determines the partitioning of radioactive material between the salts and cover gas.…”

Section: Molten Salt Chemistry and Off-gas Monitoringmentioning

confidence: 99%

Molten Salt Reactor Fundamental Safety Function PIRT

Holcomb

Huning

Muhlheim

et al. 2021

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The phenomenon identification and ranking table (PIRT) process was employed to evaluate the current capability to assess the ability of liquid-salt-fueled molten salt reactors to achieve their fundamental safety functions (FSFs). The PIRT process provides a structured mechanism to elicit and document expert opinions on the most important phenomena and the corresponding level of knowledge with regard to achieving the FSFs. The PIRT panel included reactor developers, accident progression evaluation tool developers, US Department of Energy (DOE) national laboratory technical staff, university researchers, and US Nuclear Regulatory Commission (NRC) staff. The information-gathering process concentrated on phenomena related to accidents in which the fuel salt-including any in the cover gas-has been released from the first barrier layer. This information-gathering process included identifying all potential accidents that could result in the release of a substantial amount of radionuclides that could breach or bypass the first barrier. The PIRT did not identify any previously unrecognized systemic vulnerabilities. However, the elicitation process identified several areas with low levels of knowledge and significant potential impact on accident progression. These areas either require additional research to improve the state of knowledge or additional design conservatism to accommodate the remaining unknowns.

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