Here's one from the 1960s used to determine the power coefficient of reactivity for a sodium-cooled graphite moderated reactor in Nebraska. https://babel.hathi

Here's one from the 1960s used to determine the power coefficient of reactivity for a sodium-cooled graphite moderated reactor in Nebraska. https://babel.hathitrust.org/cgi/pt?id=mdp.39015095040682&view=1up&seq=32 https://babel.hathitrust.org/cgi/pt?id=mdp.39015095040682&vi...