Shutdown dose rates at ITER equatorial ports considering radiation cross-talk from torus cryopump lower port

Juárez, R.; Pampin, R.; Levesy, B.; Moro, F.; Suárez, Alejandro; Sanz, J.

doi:10.1016/j.fusengdes.2015.07.027

Cited by 22 publications

(16 citation statements)

References 5 publications

(4 reference statements)

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“…For L1 level, the TCP-LP background is obvious in in the sectors placed above TCPs: #10, #12, #16 and #18. From previous work, the influence of the TCP-LP on the equatorial ports above them in terms of radiation levels is known to be significant [5]. This is the reason why those ports differ with respect to the rest of the corresponding representative tesserae.…”

Section: Representative Ports For the Mosaic Sourcementioning

confidence: 98%

“…To represent adequately a 360° radiation source impinging the bio-shield, one needs somehow to assemble information of 18 sectors of 20° each and computed by making use of the 40° models. This is challenging, among other things, because cross-talk between neighboring ports is known to play a relevant role in certain sectors [5]. And it also represents a significant computational load.…”

Section: Challenges To the Plasma Radiation Source Modellingmentioning

confidence: 99%

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ITER plasma source and building modelling to produce radiation maps

et al. 2018

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The ITER Tokamak Complex is the civil structure that will host the ITER Tokamak and the largest part of the associated systems. The dimensions are 120 m × 80 m × 60 m, built mostly of concrete, with over one thousand penetrations. During ITER operation, a radiation field will spread throughout the complex from diverse radiation sources. It must be characterized to check the compliance with the limits for electronics allocation and human intervention. However, the production of radiation maps in the ITER Tokamak Complex is a task of paramount sophistication due to challenges to adequately model in MCNP the radiation sources involved. In this work, two important methodological upgrades are presented. First, a new MCNP model of the Tokamak Complex, conceived to be computationally stable while capturing a conservative representation of the baseline. Second, a novel approach to model the plasma source, called a mosaic source, allows an unprecedented degree of realism and accuracy in terms of capturing the port specificities. Both represent a step change in the capacity to produce ITER radiation maps with increased reliability, augmenting previous versions. Examples of partial radiation maps are provided considering both methodological upgrades.

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Section: Representative Ports For the Mosaic Sourcementioning

confidence: 98%

Section: Challenges To the Plasma Radiation Source Modellingmentioning

confidence: 99%

ITER plasma source and building modelling to produce radiation maps

et al. 2018

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“…Previous studies have already addressed the characterization of the nuclear environment of the ITER TCPs, although with partial scopes in different senses. Some radiation-related quantities in the port cells were determined [2,3] and a relevant cross-talk to ITER equatorial ports was identified [4]. In [5,6], a shielding proposal to mitigate this cross-talk was made.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the D1SUNED code [9] has been developed, which is an adaptation of MCNP5 v1.60 code [10] for the determination of photon decay related quantities based on the direct 1-step (D1S) methodology [11]. It introduces relevant enhancements with respect to the previous tools considered in the TCP characterization [2][3][4][5][6]. For instance, the treatment of a broader fraction of the radioactive inventory (compared to [2,3]), the determination of quantities in 3D spatial distributions and the breakdown of the SDDR by activation groups are of relevance for this case.…”

Section: Introductionmentioning

confidence: 99%

Nuclear analysis of the ITER torus cryopumps

et al. 2019

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The ITER Tokamak will feature six torus cryopumps (TCP) to maintain the vacuum requirements inside the vacuum vessel for plasma operation. They will be connected to the ITER vacuum vessel through the lower ducts, which have limited shielding to ensure an efficient pumping. Therefore, these ducts will represent a relevant path for radiation to travel from the plasma and affect diverse aspects of the ITER facility, such as the electronics allocation or the maintenance operations during the machine shutdown. Previous analyses have addressed these important aspects. Nonetheless, limitations in those studies and design evolution have justified a new analysis, specifically dedicated to the TCP final design review. The results of the nuclear analysis are presented here focusing on the B1 level port cell #4. The TCP design and the associated and neighboring equipment have evolved and updated models have been considered. The TCP modelling has required an explicit heterogeneous treatment of the internal parts. The radiation source from the divertor cooling water pipes running along the port cell ceiling has been considered with the latest available source definition. In terms of methodology, one major improvement has been the modelling of the radiation transmission from C-model to the Tokamak Complex model. Another important improvement has been the consideration of D1SUNED for the determination of shutdown dose rates, covering a broader fraction of the radioactive inventory than in previous studies. The following quantities have been determined: neutron flux, absorbed dose to silicon, 1 MeV equivalent neutron fluence and shutdown dose rates (SDDR) after 10 6 s of cooling time. Finally, a set of proposals have been made to considerably mitigate the SDDR after 10 6 s of cooling. This work represents a realistic and matured source of information of the radiation environment in the ITER TCP port cells as presented in the final design review.

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“…Actually, recent studies [2] have shown that this project criterion is particularly challenging. Improvements are sought in the design of the shielding of the radiation streaming through the gaps and penetrations (adopting optical labyrinths) and in the choice of materials (use of boron carbide as neutron absorber).…”

Section: Introductionmentioning

confidence: 99%

A Monte-Carlo Benchmark of TRIPOLI-4® and MCNP on ITER neutronics

et al. 2017

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Abstract. Radiation protection and shielding studies are often based on the extensive use of 3D Monte-Carlo neutron and photon transport simulations. ITER organization hence recommends the use of MCNP-5 code (version 1.60), in association with the FENDL-2.1 neutron cross section data library, specifically dedicated to fusion applications. The MCNP reference model of the ITER tokamak, the 'C-lite', is being continuously developed and improved. This article proposes to develop an alternative model, equivalent to the 'C-lite', but for the Monte-Carlo code TRIPOLI-4®. A benchmark study is defined to test this new model. Since one of the most critical areas for ITER neutronics analysis concerns the assessment of radiation levels and Shutdown Dose Rates (SDDR) behind the Equatorial Port Plugs (EPP), the benchmark is conducted to compare the neutron flux through the EPP. This problem is quite challenging with regard to the complex geometry and considering the important neutron flux attenuation ranging from 10 14 down to 10 8 n•cm -2 •s -1 . Such code-to-code comparison provides independent validation of the Monte-Carlo simulations, improving the confidence in neutronic results.

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Shutdown dose rates at ITER equatorial ports considering radiation cross-talk from torus cryopump lower port

Cited by 22 publications

References 5 publications

ITER plasma source and building modelling to produce radiation maps

ITER plasma source and building modelling to produce radiation maps

Nuclear analysis of the ITER torus cryopumps

A Monte-Carlo Benchmark of TRIPOLI-4® and MCNP on ITER neutronics

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