Tritium retention measurements by accelerator mass spectrometry and full combustion of W-coated and uncoated CFC tiles from the JET divertor

Stan-Sion, C.; Bekris, N.; Ķizāne, Gunta; Enăchescu, M.; Likonen, J.; Halitovs, M.; Petre, A.; Contributors, Jet

doi:10.1088/0029-5515/56/4/046015

Cited by 8 publications

(5 citation statements)

References 36 publications

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“…The AMS system at the 9 MV tandem accelerator was upgraded in the past (Enachescu, Lazarev and Stan-Sion 2006; Stan-Sion and Enachescu 2015) to allow depth profiling (DP) of the elemental concentration of rare isotopes in materials. AMS-DP was intensively used for applications in the frame of the EURATOM program (Stan-Sion et al 2014b; Stan-Sion 2016; Enachescu 2017).…”

Section: Experimental Methodsmentioning

confidence: 99%

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¹⁴C High Concentration Measurements with Relevance for Decommissioning of Nuclear Reactors

Enăchescu

Stan-Sion

2019

Radiocarbon

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Decommissioning of nuclear reactors requires determination of all remnant long-lived isotopes that were produced during their long functioning time of the respective facilities. Radiocarbon (14C) is such an isotope (T1/2 = 5730 yr), widely produced by neutron reactions in a thermal column of a nuclear reactor. Accelerator mass spectrometry (AMS) uses 14C for precise dating of up to 50,000 years old archaeological artifacts. This study presents a premier AMS measurement of high concentrated 14C samples that are strictly forbidden in laboratories dedicated to perform 14C dating. The determined 14C activities range from the natural level (isotopic ratio 14C/12C = 1.2 × 10–12) up to values of 10,000 times higher. 14C bulk and depth profile concentrations were measured in the thermal column disks of a decommissioned nuclear reactor. Results have shown that the 14C concentration in the thermal column, close the reactor core is about 75 kBq/g and decreases to 0.7 Bq/g and the end of the column. Such AMS measurements are applicable for decommissioning and waste management of nuclear reactors.

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Section: Experimental Methodsmentioning

confidence: 99%

“…The other one is based on our multipurpose 9 MV tandem accelerator, an AMS facility that we built 17 years ago (Stan-Sion et al 2010). It has been intensively used in the frame of the Euratom Program, for the depth profiling of tritium high dose concentrations (Stan-Sion et al 2014b, 2016).…”

Section: Introductionmentioning

confidence: 99%

¹⁴C High Concentration Measurements with Relevance for Decommissioning of Nuclear Reactors

Enăchescu

Stan-Sion

2019

Radiocarbon

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“…Such investigations are related to the important issue of reducing the tritium retention in the protection carbon tiles of the fusion reactor vessel by coating them with tungsten or beryllium. Figure 8 shows how the tungsten material covering the tile retains by far much less tritium in comparison with the surface layer of the pure carbon (non coated) protection tile [33]. From the surface DP spectrum presented in Figure 8 it could be understood that a tungsten layer can stop the penetration of tritium and reduce the retention by more than ten times.…”

Section: -6mentioning

confidence: 98%

AMS with light nuclei at small accelerators

Stan-Sion

Enăchescu

2017

AIP Conference Proceedings

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Abstract. AMS applications with lighter nuclei are presented. It will be shown how Carbon-14, Boron-10, Beryllium-10, and Tritium-3 can be used to provide valuable information in forensic science, environmental physics, nuclear pollution, in material science and for diagnose of the plasma confinement in fusion reactors. Small accelerators are reliable, efficient and possess the highest ion beam transmissions that confer high precision in measurements.

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“…Its retention in materials leads not only to fuel loss but also to radioactive contamination. The safety of future fusion devices is greatly dependent on the amount of T retention in materials [3][4][5][6][7]. Although tungsten (W), one of the preferred PFMs, has the advantage of low HIs retention [8][9][10][11][12], there will still be a large amount of T retained in W due to a significant number of trapping sites (TS) generated under the irradiation of 14.1 MeV fusion neutrons.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of hydrogen isotope exchange for tritium removal in plasma-facing materials: a multi-scale investigation

Sun,

Hao,

Chen

et al. 2024

Nucl. Fusion

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The safety of future fusion reactors is critically dependent on the tritium (T) retention in plasma-facing materials. Hydrogen isotope exchange offers a method to redistribute hydrogen isotopes within solid materials, presenting a feasible approach for removing T from bulk materials and trapped by strong trapping sites. Nonetheless, unraveling the intricate mechanism behind hydrogen isotope exchange remains an urgent yet formidable challenge. This study undertakes a comprehensive investigation into the mechanism of hydrogen isotope exchange in tungsten materials across multiple scales. First, we developed a multi-component hydrogen isotope transport and exchange model (HIDTX) based on classical rate theory. The model validation was further carried out, demonstrating good consistency with the well-controlled laboratory experiments. From the results of different comparative models in HIDTX, it is found that the reduction in deuterium retention due to hydrogen isotope exchange was primarily driven by three synergistic effects: competitive re-trapping, collision, and swapping effects. Through molecular dynamics and first-principles calculations, the microscopic mechanism of hydrogen isotope exchange was revealed to be that the presence of hydrogen atoms in the interstitial sites surrounding a vacancy in tungsten decreased the binding energy between the vacancy and hydrogen. Meanwhile, we discovered that the combination of thermal desorption and hydrogen isotope exchange can significantly lower the temperature required for the hydrogen removal and enhance the removal rate. Particularly, the hydrogen removal time can be shortened by approximately 95% with simultaneous hydrogen isotope exchange compared to that with only thermal desorption. This work provides a practical guideline for comprehending and subsequently designing for efficient T removal in future nuclear fusion materials.

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Tritium retention measurements by accelerator mass spectrometry and full combustion of W-coated and uncoated CFC tiles from the JET divertor

Cited by 8 publications

References 36 publications

¹⁴C High Concentration Measurements with Relevance for Decommissioning of Nuclear Reactors

¹⁴C High Concentration Measurements with Relevance for Decommissioning of Nuclear Reactors

AMS with light nuclei at small accelerators

Mechanism of hydrogen isotope exchange for tritium removal in plasma-facing materials: a multi-scale investigation

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Tritium retention measurements by accelerator mass spectrometry and full combustion of W-coated and uncoated CFC tiles from the JET divertor

Cited by 8 publications

References 36 publications

14C High Concentration Measurements with Relevance for Decommissioning of Nuclear Reactors

14C High Concentration Measurements with Relevance for Decommissioning of Nuclear Reactors

AMS with light nuclei at small accelerators

Mechanism of hydrogen isotope exchange for tritium removal in plasma-facing materials: a multi-scale investigation

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¹⁴C High Concentration Measurements with Relevance for Decommissioning of Nuclear Reactors

¹⁴C High Concentration Measurements with Relevance for Decommissioning of Nuclear Reactors