This document was first requested, but fully denied, in ISCAP appeal number 2009-054-doc3. It was a CIA document, and it was only referred to by “Title and Date: [Classified], 1976.”
Originally, The Black Vault requested it in 2016, but it was reviewed and denied again. In 2018, since two years had passed, another Mandatory Declassification Review (MDR) request was filed by The Black Vault.
This yielded a response in March of 2020, and about 50% of the record was released. Although much is redacted; the history is partially revealed.
Possible Resumption of Negotiations for US Reactor, Iran, February 1976 [4 Pages, 1.2MB]