Neutron irradiation effects on plasma facing materials

Barabash, V.; Federici, G.; Rödig, M.; Snead, Lance Lewis; Wu, C.H.

doi:10.1016/s0022-3115(00)00203-8

Cited by 120 publications

(70 citation statements)

References 45 publications

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“…Furthermore, irradiation of W with fusion neutrons creates several radioactive isotopes of tungsten and rhenium which might have effects on behavior of tritium in the n-irradiated W. Note that for W divertor elements in ITER, the level of neutron-induced displacement damage for whole campaign calculated with a displacement threshold energy of E d = 38 eV 1 can reach 0.7 displacements per atom (dpa) [1], whereas in DEMO reactor the damage rate for W tiles is estimated to be 20-40 dpa per operational year [2]. Hydrogen retention in n-irradiated tungsten will occur throughout the bulk of the material and, therefore, there is the potential for large tritium inventories in fusion reactors [1,3] The best way to investigate the influence of n-produced defects on hydrogen isotope inventory in W is to have a source of fusion neutrons which still does not exist. Another possibility is an irradiation of W samples with fast neutrons (E > 0.1 MeV) in nuclear fission reactors [4,5,6,7].…”

Section: Introductionmentioning

confidence: 99%

Deuterium retention in tungsten damaged with W ions to various damage levels

Alimov

Hatano

Tyburska-Püschel

et al. 2013

Journal of Nuclear Materials

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Highlights W samples were pre-irradiated with 4.8 and 20 MeV W ions to various displacements per atom (dpa). Under following exposure to D plasmas radiation-induced defects were occupied by diffusing D atoms. At ≥ 0.1 dpa, the D concentration in the damage zone demonstrated weak dependence on the damage level. AbstractW samples were irradiated at 300 and 573 K with 4.8 and 20 MeV W ions to displacement damage levels in the range from 0.022 to 50 displacements per atom at the damage peak. 50 m thick W samples were exposed to high flux D plasma at 550 K on the side opposite to the damaged one, whereas 2 mm thick W samples were exposed to low flux D plasma at 403 K on the damaged side. Trapping of deuterium at displacement damage was examined by the D( 3 He, p) 4 He nuclear reaction with 3 He energies between 0.69 and 4.0 MeV allowing determination of the D concentration up to a depth of 6 lm. It was found that (i) at the damage level above 0.1 dpa, the concentration of the W-ion-induced defects responsible for trapping of diffusing D atoms depended very weakly on the numbers of displacements per atom, and (ii) the quasi-saturation concentration of the defects decreased by a factor of two as the W-ion irradiation temperature increased from 300 to 573 K.2

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Section: Introductionmentioning

confidence: 99%

Deuterium retention in tungsten damaged with W ions to various damage levels

Alimov

Hatano

Tyburska-Püschel

et al. 2013

Journal of Nuclear Materials

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“…Neutron irradiation generates displacements in the bulk of W and creates thus defects at which hydrogen isotopes can be trapped [1,2]. These processes lead to concerns about tritium inventory in the n-irradiated W after long-term deuterium-tritium plasma exposure.…”

Section: Introductionmentioning

confidence: 99%

The effect of displacement damage on deuterium retention in tungsten exposed to D neutrals and D2 gas

Alimov

Hatano

Sugiyama

et al. 2013

Journal of Nuclear Materials

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Samples of polycrystalline ITER-grade W and recrystallized W were irradiated at room temperature with 20 MeV W ions to displacement damage up to 0.5 dpa. The damaged W samples were then exposed to (i) D neutrals at 403-573 K and (ii) D2 gas at 673-1073 K and pressures of 1.2 and 100 kPa. Trapping of deuterium in the damage zone was examined by the K, on the D 2 gas pressure. Thermal desorption spectra allowed a conclusion that deuterium is mainly accumulated in the form of D atoms bound to inner walls of vacancy clusters.

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“…In a reactor neutron irradiation will lead to activation and to changes in the mechanical properties of W [14,15]. For the moderate neutron fluency of ITER (0.3-0.5 dpa, displacements per atom [14]) no critical deterioration of the performance of W as an armour material is foreseen.…”

Section: Materials Propertiesmentioning

confidence: 99%

“…For the moderate neutron fluency of ITER (0.3-0.5 dpa, displacements per atom [14]) no critical deterioration of the performance of W as an armour material is foreseen. However, for the application of W in DEMO or a commercial reactor further R & D is required.…”

Section: Materials Propertiesmentioning

confidence: 99%

“…Since the integrated cross section of (n,γ) is higher than that of (n,2n), W will transmute to Re followed by Os. W becomes brittle after neutron irradiation due to radiation hardening and loss of strength at grain boundaries which lead to an increase in the ductile to brittle transition temperature (DBTT) [14]. Therefore, it is proposed to use W armour material without structural function and to optimise the geometry of the components to avoid crack initiation.…”

Section: Materials Propertiesmentioning

confidence: 99%

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High-Z plasma facing components in fusion devices: boundary conditions and operational experiences

Neu

2006

Phys. Scr.

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In present day fusion devices optimization of the performance and experimental freedom motivates the use of low-Z plasma facing materials. However in a future fusion reactor, for economic reasons a sufficient lifetime of the first wall components is essential. Additionally, tritium retention has to be small to meet safety requirements. Tungsten appears to be the most realistic material choice for reactor plasma facing components (PFCs) because it exhibits the lowest erosion. But besides this there are a lot of criteria which has to be fulfilled simultaineously in a reactor. Results from present day devices and from laboratory experiments confirm the advantages of high-Z PFM but also point to operational restrictions, when using them as PFCs. They are associated with the central impurity concentration, which is determined by the sputtering yield, the penetration of the impurities and their transport within the confined plasma. The restrictions could exclude successful operation of a reactor, but concomitantly there exist remedies to ameliorate their impact. Obviously some price has to be paid in terms of reduced performance but lacking of materials or concepts which could substitute high-Z PFCs, emphasis has to be put on the development and optimization of reactor relevant scenarios which incorporate the experiences and measures.

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Neutron irradiation effects on plasma facing materials

Cited by 120 publications

References 45 publications

Deuterium retention in tungsten damaged with W ions to various damage levels

Deuterium retention in tungsten damaged with W ions to various damage levels

The effect of displacement damage on deuterium retention in tungsten exposed to D neutrals and D2 gas

High-Z plasma facing components in fusion devices: boundary conditions and operational experiences

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