Activation, decay heat, and waste classification studies of the European DEMO concept

Gilbert, Mark R.; Eade, T.; Bachmann, Christian; Fischer, U.; Nigel, Taylor

doi:10.1088/1741-4326/aa5bd7

Cited by 52 publications

(50 citation statements)

References 11 publications

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“…The results in this paper are in good agreement with Ref. [42], where it is stated that the steel of the divertor will remain as ILW for decades or even centuries after shutdown. According to IAEA, this level of waste needs higher than near-surface disposal.…”

Section: Resultssupporting

confidence: 91%

Activities in Divertor Reflector and Linear Plates Using WCLL and HCPB Breeding Blanket Concepts

Breidokaité

Stankūnas

2021

Energies

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In fusion devices, such as European Demonstration Fusion Power Reactor (EU DEMO), primary neutrons can cause material activation due to the interaction between the source particles and the targeting material. Subsequently, the reactor’s inner components become activated. For safety and safe performance purposes, it is necessary to evaluate neutron-induced activities. Activities results from divertor reflector and liner plates are presented in this work. The purpose of liner shielding plates is to protect the vacuum vessel and magnet coils from neutrons. As for reflector plates, the function is to shield the cooling components under plasma-facing components from alpha particles, thermal effects, and impurities. Plates are made of Eurofer with a 3 mm layer of tungsten, while the water is used for cooling purposes. The calculations were performed using two EU DEMO MCNP (Monte Carlo N-Particles) models with different breeding blanket configurations: helium-cooled pebble bed (HCPB) and water-cooled lithium lead (WCLL). The TENDL–2017 nuclear data library has been used for activation reactions cross-sections and nuclear reactions. Activation calculations were performed using the FISPACT-II code at the end of irradiation for cooling times of 0 s–1000 years. Radionuclide analysis of divertor liner and reflector plates is also presented in this paper. The main radionuclides, with at least 1% contribution to the total value of activation characteristics, were identified for the previously mentioned cooling times.

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Section: Resultssupporting

confidence: 91%

Activities in Divertor Reflector and Linear Plates Using WCLL and HCPB Breeding Blanket Concepts

Breidokaité

Stankūnas

2021

Energies

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“…The activity induced by the neutron irradiation of W in DEMO decays to the hands-on level of 10 µSv h −1 within 100 years [9]. Thus, the W is recyclable within 100 years, which is the same situation as for the vacuum vessel [10]. It leaves two properties that should be improved-the mechanical and the oxidation properties.…”

Section: Introductionmentioning

confidence: 99%

On Oxidation Resistance Mechanisms at 1273 K of Tungsten-Based Alloys Containing Chromium and Yttria

Klein

Wegener

Litnovsky

et al. 2018

Metals

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Tungsten (W) is currently deemed the main candidate for the plasma-facing armor material of the first wall of future fusion reactors, such as DEMO. Advantages of W include a high melting point, high thermal conductivity, low tritium retention, and low erosion yield. However, was an accident to occur, air ingress into the vacuum vessel could occur and the temperature of the first wall could reach 1200 K to 1450 K due to nuclear decay heat. In the absence of cooling, the temperature remains in that range for several weeks. At these temperatures, the radioactive tungsten oxidizes and then volatilizes. Smart W alloys are therefore being developed. Smart alloys are supposed to preserve properties of W during plasma operation while suppressing tungsten oxide formation in case of an accident. This study focuses on investigations of thin film smart alloys produced by magnetron sputtering. These alloys provide an idealistic system with a homogeneous distribution of the elements W, chromium (Cr), and yttrium (Y) on an atomic scale. The recommended composition is W with 12 weight % of Cr and 0.5 weight % of Y. Passivation and a suppression of WO 3 sublimation is shown. For the first time, the mechanisms yielding the improved oxidation resistance are analyzed in detail. A protective Cr 2 O 3 layer forms at the surface. The different stages of the oxidation processes up to the failure of the protective function are analyzed for the first time. Using 18 O as a tracer, it is shown for the first time that the oxide growth occurs at the surface of the protective oxide. The Cr is continuously replenished from the bulk of the sample, including the Cr-rich phase which forms during exposure at 1273 K. A homogenous distribution of yttria within the W-matrix, which is preserved during oxidation, is a peculiarity of the analyzed alloy. Further, an Y-enriched nucleation site is found at the interface between metal and oxide. This nucleation sites are deemed to be crucial for the improved oxidation resistance.

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“…3,4 Considering safety, the formation of long-lived radioactive isotopes when irradiated with neutrons and a tritium inventory has to be prevented. [5][6][7][8][9] The choice of plasma-facing components represents a challenging task. Due to its high melting point (3410 C), low swelling, high-energy threshold for sputtering, and excellent mechanical properties, tungsten is envisaged as a prime candidate plasma-facing material for a future power plant.…”

mentioning

confidence: 99%

Monte Carlo simulations of pure tungsten and advanced “smart” tungsten alloys under helium bombardment for future fusion power plants

Laaziz

Asmae

Fechtal

et al. 2021

Surface & Interface Analysis

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Activation, decay heat, and waste classification studies of the European DEMO concept

Cited by 52 publications

References 11 publications

Activities in Divertor Reflector and Linear Plates Using WCLL and HCPB Breeding Blanket Concepts

Activities in Divertor Reflector and Linear Plates Using WCLL and HCPB Breeding Blanket Concepts

On Oxidation Resistance Mechanisms at 1273 K of Tungsten-Based Alloys Containing Chromium and Yttria

Monte Carlo simulations of pure tungsten and advanced “smart” tungsten alloys under helium bombardment for future fusion power plants

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