Determination of tritium activity and chemical forms in the exhaust gas from a large fusion test device

Tanaka, Masahiro; Kato, Hiromi; Suzuki, Naoyuki; Iwata, Chie

doi:10.1007/s10967-018-6075-y

Cited by 15 publications

(7 citation statements)

References 27 publications

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“…3. The catalyst is supported on a metal honeycomb [15], and was heated by a heater to 668 K to oxidize tritium in chemical forms of tritiated hydrogen gas and tritiated hydrocarbons into tritiated water vapor. The tritiated water was collected by water bubblers, Fig.…”

Section: Full-combustion Methodsmentioning

confidence: 99%

Investigation of remaining tritium in the LHD vacuum vessel after the first deuterium experimental campaign

Masuzaki¹,

Otsuka²,

Ogawa³

et al. 2020

Phys. Scr.

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To reveal the triton transport and the tritium migration in a deuterium plasma experiment in the Large Helical Device (LHD), the distribution of the remaining tritium in divertor tiles made of graphite after the first deuterium plasma experimental campaign in 2017 was investigated. In this study, tritium contents in divertor tiles have been measured by using a full-combustion method. The asymmetric tritium retention in divertor tiles located at symmetric positions, which was found in the previous study by the surface tritium measurement using an imaging plate technique, has been confirmed by the results of the full-combustion method. The asymmetry is considered to be attributed to the asymmetric distribution of lost-points of energetic tritons in divertor. A depth profile of remaining tritium in a divertor tile estimated by using a combination of the imaging plate technique and a sputtering treatment shows that the peak of the profile locates at several micro-meters from the surface. This result suggests that the majority of the remaining tritium impinged upon the divertor tile as energetic tritons. In this study, a distribution of lost-points of energetic tritons has been calculated by using a Lorentz orbit following code (LORBIT) with taking into account divertor components. The obtained distribution has been compared with measured tritium distributions on divertor tiles. The measured and calculated distributions are similar to each other, but they are not the same. The difference between them can be attributed to plasma exposures during and after the deuterium plasma campaign.

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Section: Full-combustion Methodsmentioning

confidence: 99%

Investigation of remaining tritium in the LHD vacuum vessel after the first deuterium experimental campaign

Masuzaki¹,

Otsuka²,

Ogawa³

et al. 2020

Phys. Scr.

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“…Because the EDS is connected to all exhaust gas lines from the LHD system, the inlet of the EDS is suitable for observing exhaust gas composition, including hydrogen isotopes. To observe tritium and gas composition in the exhaust gas, various gas analysis instruments belonging to a GC system, including an RGA system, a dew point hygrometer, an optical-type hydrogen sensor, an ionization chamber, an original water bubbler system, and a Fourier transform infrared (FTIR) spectroscopy system with a long optical path gas cell, were installed and have been previously operated [14,15]. Using these instruments, the exhaust behavior of tritium from the LHD was revealed in the first deuterium plasma experimental campaign [16,17].…”

Section: Monitoring Exhaust Gas From the Lhd And The Wall Conditioning Proceduresmentioning

confidence: 99%

Detection of Ammonia and Deuterated Hydrocarbons in Exhaust Gas by Infrared Absorption Spectroscopy during Wall Conditioning

Tanaka

Kato

Suzuki

et al. 2021

Plasma and Fusion Research

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To detect ammonia and deuterated hydrocarbons in exhaust gas from the Large Helical Device (LHD), infrared absorption spectrometry, FTIR with a long optical path gas cell, was applied. Ammonia (NH 3 ) and deuterated hydrocarbons (C x H y D z ) could be detected during the first operations of wall baking at 368 K and the D 2 glow discharge conducted after vacuum vessel closure. The concentration of ammonia increased with increasing baking temperature, and deuterated ammonia was not detected. Thus, the ammonia, which likely originated from sweat of workers produced during vacuum vessel maintenance activities, was released from the vacuum vessel wall. Hydrocarbons were likely produced by chemical sputtering of carbon tiles and were deuterated by a hydrogen isotope exchange reaction due to D 2 glow discharge, while H 2 O was released from the vacuum vessel during wall baking. It was confirmed that ammonia and various types of deuterated hydrocarbons could be measured discriminately by an FTIR spectroscopy system using a long optical path gas cell.

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“…The tritium monitoring devices were installed in the EDS. Regarding the MS system, the original water bubbler system [22] and the ionization chamber (Y221G0300, Ohkura Electric Co., Ltd.) were prepared for the plasma experiment. The water bubbler system is for the measurement of average tritium concentration and the discrimination of tritium chemical forms.…”

Section: Tritium Monitoring Devicesmentioning

confidence: 99%

Tritium Balance in Large Helical Device during and after the First Deuterium Plasma Experiment Campaign

Tanaka

Kato

Suzuki

et al. 2020

Plasma and Fusion Research

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The Large Helical Device (LHD) started the deuterium plasma experiment on March 7, 2017. Approximately 6.4 GBq of tritium was produced in the first deuterium plasma experiment campaign and were utilized as tracers for the investigation of release behavior and the balance of tritium in the LHD vacuum vessel. To determine the tritium balance in LHD, the tritium release from the vacuum vessel was continually observed during the plasma experiment period and the vacuum vessel maintenance activities. The tritium exhaust rate was approximately 32.8% at the end of the plasma experiment. After the plasma experiment, the vacuum vessel was ventilated by room air for the maintenance activity and the tritium release from the in-vessel components was observed. The tritium release rate gradually decreased and became constant after four-month in spite of water vapor concentration. It is suggested that the tritium release mechanism from the vacuum vessel is a diffusion-limited process from the bulk. The tritium release amount during the maintenance activity for one year was approximately 5.0%. Considering the decrease of tritium decay for 1.5 years, tritium inventory in LHD was estimated to be approximately 3.66 GBq (57.2%) at the end of maintenance activity.

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Determination of tritium activity and chemical forms in the exhaust gas from a large fusion test device

Cited by 15 publications

References 27 publications

Investigation of remaining tritium in the LHD vacuum vessel after the first deuterium experimental campaign

Investigation of remaining tritium in the LHD vacuum vessel after the first deuterium experimental campaign

Detection of Ammonia and Deuterated Hydrocarbons in Exhaust Gas by Infrared Absorption Spectroscopy during Wall Conditioning

Tritium Balance in Large Helical Device during and after the First Deuterium Plasma Experiment Campaign

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