Assessment of shutdown dose rates in the ITER Collective Thomson Scattering system and in equatorial port plug 12

Chambon, Amalia; Luís, R.; Klinkby, E. B.; Nietiadi, Yohanes; Rechena, Diogo; Gonçalves, B.; Jessen, M.; Korsholm, S. B.; Larsen, A.W.; Lauritzen, Bent; Rasmussen, Jesper; Salewski, M.; Fabbri, Marco; Morillo, C.

doi:10.1088/1748-0221/16/12/c12001

Cited by 3 publications

(3 citation statements)

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“…The analysis also confirmed that the present design of the CTS system remains compliant with the radiation safety requirements, and that from the neutronics point of view, no further design optimization of the CTS system is needed 43 .…”

Section: Please Cite This Article As Doi:101063/50101867supporting

confidence: 73%

“…and apertures for the components and the microwave beams) has closely accompanied the development of the design. The purpose has been to determine if modifications done for diagnostic performance reasons would violate the requirements on the shutdown dose rates (SDDR) at the equatorial port plug closure plate in the port interspace for hand-on maintenance purpose [41][42][43] . By requirement, the dose level in the ports cells, where hands-on maintenance is planned, should not exceed 100 μSv/h 10 6 seconds (~12 days) after shutdown.…”

Section: Please Cite This Article As Doi:101063/50101867mentioning

confidence: 99%

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ITER collective Thomson scattering—Preparing to diagnose fusion-born alpha particles (invited)

Korsholm

Chambon

Gonçalves³

et al. 2022

Review of Scientific Instruments

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The ITER Collective Thomson scattering (CTS) diagnostic will measure the dynamics of fusion-born alpha particles in the burning ITER plasma by scattering a 1 MW 60 GHz gyrotron beam off fast-ion induced fluctuations in the plasma. The diagnostic will have seven measurement volumes across the ITER cross section and will resolve the alpha particle energies in the range from 300 keV to 3.5 MeV; importantly, the CTS diagnostic is the only diagnostic capable of measuring confined alpha particles for energies below ∼1.7 MeV and will also be sensitive to the other fast-ion populations. The temporal resolution is 100 ms, allowing the capture of dynamics on that timescale, and the typical spatial resolution is 10–50 cm. The development and design of the in-vessel and primary parts of the CTS diagnostic has been completed. This marks the beginning of a new phase of preparation to maximize the scientific benefit of the diagnostic, e.g., by investigating the capability to contribute to the determination of the fuel-ion ratio and the bulk ion temperature as well as integrating data analysis with other fast-ion and bulk-ion diagnostics.

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Section: Please Cite This Article As Doi:101063/50101867supporting

confidence: 73%

Section: Please Cite This Article As Doi:101063/50101867mentioning

confidence: 99%

ITER collective Thomson scattering—Preparing to diagnose fusion-born alpha particles (invited)

Korsholm

Chambon

Gonçalves³

et al. 2022

Review of Scientific Instruments

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“…As mentioned before, there are no limits defined for the neutron and gamma fluxes in the DEMO port cell, and no calculations of shutdown dose rates are provided here. However, it seems feasible, based on the simulation experience from ITER (although the dose rates will depend on the components present in the port cell and on the integrated fluxes) [62], to comply with the limit of 100 µSv/h in the port cell 12 days after shutdown with neutron fluxes below 1 × 10 8 n cm −2 s −1 reaching the port cell. Nevertheless, shutdown dose rate simulations with models of the port cell components are required to assess the compliance with the limit.…”

Section: Alternative Configuration Of the X-ray Spectroscopy Diagnosticmentioning

confidence: 99%

Neutronics Simulations for DEMO Diagnostics

Luís

Nietiadi

Quercia

et al. 2023

Sensors

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One of the main challenges in the development of a plasma diagnostic and control system for DEMO is the need to cope with unprecedented radiation levels in a tokamak during long operation periods. A list of diagnostics required for plasma control has been developed during the pre-conceptual design phase. Different approaches are proposed for the integration of these diagnostics in DEMO: in equatorial and upper ports, in the divertor cassette, on the inner and outer surfaces of the vacuum vessel and in diagnostic slim cassettes, a modular approach developed for diagnostics requiring access to the plasma from several poloidal positions. According to each integration approach, diagnostics will be exposed to different radiation levels, with a considerable impact on their design. This paper provides a broad overview of the radiation environment that diagnostics in DEMO are expected to face. Using the water-cooled lithium lead blanket configuration as a reference, neutronics simulations were performed for pre-conceptual designs of in-vessel, ex-vessel and equatorial port diagnostics representative of each integration approach. Flux and nuclear load calculations are provided for several sub-systems, along with estimations of radiation streaming to the ex-vessel for alternative design configurations. The results can be used as a reference by diagnostic designers.

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Superconductor based, tomographic, neutron diagnostics for fusion power monitoring

Brock,

Chambon,

Bahl

et al. 2024

Review of Scientific Instruments

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We propose a scalable system of compact, superconducting neutron monitors, which can be embedded in any existing cryogenic infrastructure of a fusion system. The pixel-based nature of the detectors allows them to be placed at intervals following the circumference of a cooled zone, e.g., a field coil, thus allowing for a tomographic measurement of the neutron flux surrounding the plasma. An early stage prototype of the superconducting bolometer is described, and the key results of a previous feasibility study of this prototype performed with cold neutrons are summarized. The bolometer can be adapted for use with fast neutrons by altering the composition and geometry of the neutron-to-heat conversion layer. This paper describes the initial feasibility considerations for implementation in a superconducting tokamak. The sensor is based on a high-temperature superconductor, making it possible to select the operation temperature in the range 1–90 K. Neutron flux numbers were found using the ITER MCNP reference model, and these were embedded in a TOPAS model to find the expected signal measured by the bolometer at the position of a toroidal field coil. The results at the coil position indicate suitable operation levels in terms of the magnitude of the measured signal, with a measurable signal of several ohm, which is much smaller than the saturation energy of the detector. Radiation hardness is estimated and found to be on the order of at least 40 years for the relevant radiation levels. The upcoming investigation activities of the project are described for both radiation testing and analytical modeling.

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Assessment of shutdown dose rates in the ITER Collective Thomson Scattering system and in equatorial port plug 12

Cited by 3 publications

References 10 publications

ITER collective Thomson scattering—Preparing to diagnose fusion-born alpha particles (invited)

ITER collective Thomson scattering—Preparing to diagnose fusion-born alpha particles (invited)

Neutronics Simulations for DEMO Diagnostics

Superconductor based, tomographic, neutron diagnostics for fusion power monitoring

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