Here's a bunch I've collected for my atompunk timeline:
“I can't afford to differentiate between the incompetent and the unfortunate.” -Gen. Curtis LeMay
“Politics and the atom do not mix.” -Pres. Harry S Truman
“World government has become inevitable. The choice before us is whether this government shall be agreed upon or whether we shall elect to fight a catastrophic third world war to determine who shall be master.” -Arthur H. Compton
“Modern man is obsolete.” -Norman Cousins
“We are here to make a choice between the quick and the dead. That is our business.” -Bernard Baruch, opening speech at UN atomic energy commission negotiations
“Once committed to the atom, it is impossible to draw back.” -Gen. Pierre Gallois
“It is not too much to expect that our children will enjoy in their homes electrical energy too cheap to meter...” -Lewis L. Strauss
“The release of atomic energy has not created a new problem. It has merely made more urgent the necessity of solving an existing one.” -Albert Einstein
“No country without an atom bomb could properly consider itself independent.” -Charles De Gaulle
“The discovery of nuclear reactions need not bring about the destruction of mankind any more than the discovery of matches.” -Albert Einstein
“There are no total answers, no easy answers, no cheap answers to the question of protection from nuclear attack. But there are answers.” -Fallout Protection, Pamphlet from the Office of Civil Defense
“When will I be blown up?” -William Faulkner