Haxel was a signatory of the manifesto of the "Göttinger Achtzehn" (Göttingen Eighteen). Haxel’s friend, Fritz Houtermans was married four times. Charlotte Riefenstahl, a physicist educated at the University of Göttingen, was his first and third wife in four marriages. In February 1944, Houtermans married Ilse Bartz, a chemical engineer; they worked together during the war and published a paper. Houtermans divorced Ilse and remarried Charlotte in August 1953. Haxel married Ilse after her divorce from Houtermans. The "Freundeskreis des Forschungszentrums Karlsruhe e.V." (Friends of the Karlsruhe Research Center) established and awards the "Otto-Haxel-Preis" (Otto Haxel Prize), which is given for achievements in the nuclear energy industry. In 1980, Haxel was awarded the "Otto-Hahn-Preis der Stadt Frankfurt am Main" (Otto Hahn Prize of the City of Frankfurt am Main) for his advocacy of and work on harnessing nuclear energy production. The following reports were published in "Kernphysikalische Forschungsberichte" ("Research Reports in Nuclear Physics"), an internal publication of the German "Uranverein". The reports were classified Top Secret, they had very limited distribution, and the authors were not allowed to keep copies. The reports were confiscated under the Allied Operation Alsos and sent to the United States Atomic Energy Commission for evaluation. In 1971, the reports were declassified and returned to Germany. The reports are available at the Karlsruhe Nuclear Research Center and the American Institute of Physics.