The National Security Archive's 2014 EBB 491 posting restates Project Sapphire's ~600 kg U-235 figure in pounds, and relabels it as gross weapons-grade uranium — an editorial gloss on the document it publishes, not independent corroboration

project-sapphirenuclear-historynonproliferationkazakhstanprimary-sourceverification

The DTRA after-action report's own figure — "roughly 600 kg of U-235" — reappears, converted, in the introduction to the posting that released it. The National Security Archive's Electronic Briefing Book No. 491 (posted November 17, 2014, edited by David E. Hoffman, Svetlana Savranskaya, and Thomas Blanton) describes Project Sapphire in its own editorial language as securing "more than a half-ton of highly-enriched uranium," and elsewhere as removing "the 1,320 pounds of weapons-grade uranium" from Kazakhstan. 1,320 lb converts to approximately 599 kg.

This is not independent corroboration, and the note originally recorded it as though it were. EBB 491 is the posting that publishes the DTRA after-action report — the report appears there as Document 1, "obtained through the Freedom of Information Act (FOIA) from DTRA by David E. Hoffman," who is also one of the three named editors and the author of the Dead Hand Sapphire chapter reprinted in the same posting as Document 17. The editors' summary is therefore a gloss on the document it hosts, by the person who obtained it, in the venue that released it — what sources.md calls "the same source wearing different clothes," not a different author group converging on the same figure.

What the restatement does record is a relabeling worth keeping. The DTRA report's ~600 kg is contained U-235, drawn from roughly 2,200 kg of gross HEU-bearing material; the Archive's "1,320 pounds of weapons-grade uranium" attaches that same number to what reads as gross material mass. The two cannot both be right, and the internal check confirms which slipped: 1,320 lb is 599 kg, not 2,200 kg. So the figure was converted from the primary and re-described one category up, inside the very posting that makes the primary available. The number's verbatim home, and its correct referent, remain the DTRA report itself.

Sits alongside Megatons to Megawatts as part of the same nonproliferation-material-accounting cluster: both rest on the discipline of checking a headline figure against more than one account before treating it as settled.