The IAEA's 1988 primary report confirms the Goiânia accident's mechanism: an abandoned caesium-137 teletherapy source, dismantled by two men scavenging for scrap, releasing soluble caesium chloride

radiological-medicineradionuclideshistorygoiania-accidentiaeacesium-137primary-verificationtechnical-mechanism

The IAEA's formal 1988 report traces the Goiânia accident to a caesium-137 teletherapy unit left behind when a private radiotherapy clinic (Instituto Goiano de Radioterapia) relocated without notifying Brazil's licensing authority:

"On 13 September 1987, a shielded, strongly radioactive caesium-137 source (50.9 TBq, or 1375 Ci, at the time) was removed from its protective housing in a teletherapy machine in an abandoned clinic in Goiania, Brazil, and subsequently ruptured."

Two men — not the junkyard owner who later bought the remnants — removed the source assembly, believing it had scrap value, and ruptured the capsule attempting to dismantle it at home; the junkyard owner acquired the pieces only afterwards, once the capsule had already been breached. The report records what the two men did and why ("thinking it might have some scrap value"), not what they did for a living. The source material was caesium chloride salt: "In the attempt the source capsule was ruptured. The radioactive source was in the form of caesium chloride salt, which is highly soluble and readily dispersible." That solubility is why contamination spread through direct handling and contaminated household objects rather than staying contained the way a sealed, insoluble source would have.

This is a technical-mechanism claim (Tier 1–2 required by the sourcing floor), now grounded directly in the Agency's own account rather than a paraphrase — the same document that carries the contamination count and death toll also carries the causal chain those figures are attached to. It corroborates, at Tier 1, the mechanism already sketched in this vault from a Tier-4 source.