"T" . . . . . . . . . . . . . . . . . "The \"Reactor Time Constant\", also called the reactor period, is the time during which the neutron flux density in a reactor changes by the factor e = 2.718 (e: basis of natural logarithms), when the neutron flux density increases or decreases exponentially." . . . . . . . . . . . . . "http://www.euronuclear.org/info/encyclopedia/r/reactor-time-constant.htm"^^ . . . . "Reactor Time Constant"@en . . . . "http://www.iso.org/iso/catalogue_detail?csnumber=31895"^^ . . . . . .