Structural integrity of DEMO divertor target assessed by neutron tomography

Abstract

The divertor target plates are the most exposed in-vessel components to high heat flux loads in a fusion reactor due to a combination of plasma bombardment, radiation and nuclear heating. Reliable exhaust systems of such a huge thermal power required a robust and durable divertor target with a sufficiently large heat removal capability and lifetime. In this context, it is pivotal to develop non-destructive evaluation methods to assess the structural integrity of this component that, if compromised could reduced its lifetime. In this work we have demonstrated for the first time the feasibility of using neutron tomography to detect volumetric defects within DEMO divertor mock-ups with a spatial resolution of the order of hundreds of micrometers. Neutron tomography is applicable for studying complex structures, often manufactured from exotic materials which are not favourable for conventional non-destructive evaluation methods. This technique could be effectively used during research and development cycles of fusion component design or for quality assurance during manufacturing.

Are tungsten-based nuclear fusion components truly invisible to x-ray inspection?

“…A detailed description of the mock-up manufacturing process is report in this work [8] and it has been listed in the reference for interested readers. This sample was previously studied via neutron tomography [4] on the IMAT beamline [9][10][11][12][13][14][15] at the ISIS spallation neutron source in the UK. Further, recent studies have demonstrated the feasibility of using neutron tomography to assess volumetric defects on large numbers of similar components like divertor monoblocks [13] and how those results compared with XCT measurements [16].…”

“…Further, recent studies have demonstrated the feasibility of using neutron tomography to assess volumetric defects on large numbers of similar components like divertor monoblocks [13] and how those results compared with XCT measurements [16]. From the neutron tomography tests [4], no major issues have been identified within the sample. Subsequently, the specimen was subjected to HHF loads with a single cycle at ∼8 MWm −2 on the HIVE facility [17] at United Kingdom Atomic Energy Authority (UKAEA).…”

“…As such, robust non-destructive evaluation (NDE) techniques are paramount to avoid failures and they will represent a crucial step for qualifying fusion components to any fusion regulatory codes and standards required for a commercial fusion power plant. Very recently, we have successfully demonstrated the use of neutron tomography as a non-destructive volumetric inspection technique applied to PFCs [4]. However, such inspection technology can only be accessed at dedicated large-scale facilities limiting its applicability in practice.…”

Molecular specificity in neutron imaging: the case of hydrogen adsorption in metal organic frameworks

“…Neutron imaging is one of the most promising techniques to study in situ and operando processes of interest for industrial and engineering applications [1][2][3][4][5][6][7][8][9][10][11] as well as for cultural heritage. [12][13][14][15][16][17][18][19] The technique exploits the high penetration power of neutrons, along with a number of features in the way they interact with nuclei and isotopes, and the fact that neutrons are available in dedicated research infrastructures in a broad range of energies spanning several orders of magnitude, from tens of meV to hundreds of MeV.…”