Few U.S. atomic reactors have completed safety changes mandated in the wake of the Three Mile Island accident although a decade has passed, Nuclear Regulatory Commission records show. Only 24 of the nation’s 112 licensed commercial reactors have installed all 149 changes required. Of the 88 reactors not in compliance, several will not finish modifications until “well into the 1990s,” said Rep. Edward J. Markey (D-Mass.), an NRC critic who requested the data. The NRC documents showed that 23 reactors have failed to install display consoles to help reactor operators more quickly determine a plant’s safety status. That had been designated a top priority by the NRC. Thirteen reactors have not installed instruments specifically to detect core cooling, a requirement that also was given a top priority by the agency.