Maneschg et al. (2008) find manmade cobalt-60 in all 13 stainless-steel batches screened for GERDA, at about 19 mBq/kg, and Heusser is a co-author

materialsnuclearcobalt-60steelmakinglow-background-physicsgerdaindependence

Maneschg and seven co-authors screened 13 stainless-steel batches by low-level gamma spectrometry with germanium detectors at two underground laboratories, as candidate cryostat material for the GERDA experiment. The abstract reports that "only the manmade 60Co-isotope is present in all samples with a higher concentration of around 19 mBq/kg"; primordial and cosmogenic nuclides were near or below about 1 mBq/kg.

The abstract states no mechanism for the cobalt-60. A search-engine summary (not quotable) reports that the full text ties the lowest-cobalt-60 samples to scrap-free production; that is unconfirmed here and flagged [unverified-mechanism].

Independence. G. Heusser is a listed co-author. The paper and Heusser's 1995 review are therefore not independent sources for the furnace-gauge story, and agreement between them would not count as corroboration under the vault's independence test. The measurement is a useful ubiquity datum alongside claim-pandax-ii-2016-modern-steel-still-required-scrap-avoidance-for-low-background and claim-zhang-2016-names-scrap-metal-feedstock-as-commercial-steels-cobalt-60-source, not a mechanism source. It is also silent on atmospheric entrainment (claim-no-primary-source-names-atmospheric-entrainment-as-steels-cobalt-60-pathway).

Related open verification: question-verify-low-background-steel-fallout-contamination-mechanism.