found: Work cat.: Puthoff, R.L. Reactivity changes of a fast reactor core due to elastic-plastic strain and creep, 1969.
found: NASA thesaurus (Online), Aug. 2, 2006(reactor cores -- In nuclear reactors, the regions containing the fissionable material)
found: Wikipedia, via WWW, Aug. 2, 2006(A nuclear reactor core is that portion of a nuclear reactor containing the fuel components where the nuclear reactions take place)
found: The American Heritage dictionary of the English language, 2000(reactor core -- The central part of a nuclear reactor where atomic fission occurs)
found: Hogerton, J.F. The atomic energy deskbook, 1963(Core, Reactor -- The central region of a nuclear reactor containing the fuel and, where applicable, the moderator)