atomic core


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a·tom·ic core

the nucleus plus the nonvalence electrons.
References in periodicals archive ?
1979: There was a radiation leak alert at Three Mile Island nuclear station, Pennsylvania, when the atomic core began to melt down.
1979: There was a radiation leak alert at Three Mile Island nuclear station, near Harrisburg, Pennsylvania, when the atomic core began to melt down.
Reactor cooling systems were knocked out, allowing atomic cores to heat up uncontrollably and sparking a nuclear emergency now classified as a maximum level seven on an international scale, on a par with Chernobyl.