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    "story_id": "mp-2026-08-09-012",
    "source_story_id": "tmp-story-arc-tritium-transport",
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    "edition_url": "https://themachinepress.com/edition/2026-08-09",
    "position": 12,
    "story_type": "dispatch",
    "section": "infrastructure",
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    "headline": "The Fusion Blanket Hid Its Inventory in Slow Water",
    "slug": "the-fusion-blanket-hid-its-inventory-in-slow-water",
    "dek": "An open multiphysics model put tritium accumulation near flow stagnation zones and made numerical stabilization the dominant uncertainty.",
    "summary": "An open multiphysics model put tritium accumulation near flow stagnation zones and made numerical stabilization the dominant uncertainty.",
    "body_text": "OpenMC, OpenFOAM and FESTIM were coupled to model neutron, fluid, heat and isotope transport in an ARC-class molten-salt breeding blanket. Under a zero-concentration inlet assumption, the steady-state calculation produced about 243 milligrams of tritium and roughly 30 minutes to steady throughput; accumulation localized in stagnation regions and fell in turbulent zones. Sensitivity was driven mainly by the numerical stabilization scheme, so the figures are model outputs, not reactor measurements.",
    "why_it_matters": "An open multiphysics model put tritium accumulation near flow stagnation zones and made numerical stabilization the dominant uncertainty.",
    "limitations": [
      "Sensitivity was driven mainly by the numerical stabilization scheme, so the figures are model outputs, not reactor measurements."
    ],
    "importance": 8,
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    "first_published_at": "2026-08-09T09:00:00.000-04:00",
    "modified_at": "2026-08-09T09:00:00.000-04:00",
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        "qualification": "Sensitivity was driven mainly by the numerical stabilization scheme, so the figures are model outputs, not reactor measurements."
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    "tags": [
      "fusion",
      "tritium",
      "multiphysics"
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    "image_url": null,
    "corrections": []
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  "sources": [
    {
      "source_id": "source-2026-08-09-012",
      "title": "arXiv preprint 2608.05398",
      "publisher": "arXiv",
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  "publisher": {
    "name": "The Machine Press",
    "url": "https://themachinepress.com",
    "description": "A daily newspaper for the age of artificial intelligence."
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  "cite_this_report": {
    "title": "The Fusion Blanket Hid Its Inventory in Slow Water",
    "publisher": "The Machine Press",
    "published_at": "2026-08-09T09:00:00.000-04:00",
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