Does a primary source confirm the mechanism by which post-1945 steelmaking bakes atmospheric fallout radionuclides (e.g. cobalt-60) into steel?

claim-low-background-steel-is-pre-1945-steel-salvaged-from-fallout-contamination rests on a Tier-4 Wikipedia summary for a technical-mechanism claim: that the Bessemer / basic-oxygen processes draw in large volumes of atmospheric air, and that air has carried anthropogenic fallout radionuclides (notably cobalt-60) since 1945, so the radionuclides are incorporated into the steel and give it a weak radioactive signature. Per the sourcing floor, a mechanism claim needs a Tier 1–2 primary; Wikipedia is a pointer, not evidence.

Why it matters. The whole "lost capability" framing depends on the pathway being real and specifically atmospheric (rather than, say, contamination from scrap feedstock or cosmogenic activation). The precise contaminant chemistry (Co-60 from where — bomb debris, reactor releases, weapons-test neutron activation of structural cobalt?) also decides whether the story is about air intake at all.

What would answer it.

• A health-physics or metallurgy primary (e.g. a peer-reviewed paper or a standards body such as the IAEA / a national metrology lab) describing the air-intake contamination pathway in steelmaking and quantifying the induced activity.
• Documentation from a low-background detector programme (particle physics or whole-body counting) explaining why they specify pre-1945 or pre-1945-adjacent steel and what isotopes they are excluding.
• Confirmation of the Scapa Flow salvage practice from a source closer than Wikipedia (e.g. Admiralty / salvage-industry records, or a detector-lab procurement account).

Until answered, the claim-note stays seedling with its [unverified-mechanism] flag intact.