Partial Nuclear Test Ban Treaty (1963)

The 1963 treaty (US, USSR, UK) that banned nuclear-weapons tests in the atmosphere, outer space, and underwater, driving most nuclear testing underground and halting the largest source of fresh fallout radionuclide injection into the atmosphere. In this vault it functions as a hinge date rather than a subject in its own right: UNSCEAR's own dose-assessment data identifies 1963 as the peak year for world-average dose from atmospheric testing, with a subsequent multi-decade decline as fallout isotopes (notably cobalt-60) decayed and diluted rather than being replenished. That decline is the entire mechanism behind the low-background-steel cluster's most counterintuitive finding — a scarcity quietly un-losing itself — and it is a genuinely different treaty from the 1996 Comprehensive Nuclear-Test-Ban Treaty that grounds this vault's separate CTBTO/radioxenon-monitoring cluster, though the two are easy to conflate.

References

• claim-low-background-steel-need-is-fading-as-atmospheric-fallout-decays · claim-low-background-steel-is-pre-1945-steel-salvaged-from-fallout-contamination · claim-low-background-steel-became-a-metaphor-for-pre-2022-ai-free-web-text · claim-unscear-primary-confirms-1963-peak-dose-and-post-1963-decline · claim-unscear-revised-1963-peak-dose-estimate-0-14-to-0-11-msv