The National Transportation Safety Board has asked the Federal Railroad Administration to use emergency powers to call in more than 20,000 freight cars for immediate replacement of hazardous wheels.

In a meeting yesterday the safety board decided to ask the FRA to have all wheels manufactured by the Southern Wheel Co. in the late 1950s and most of the 1960s with high carbon content - models 70T or UI - recalled immediately.

The board said that its investigation of "several recent derailments has disclosed that the probable causes or contributing causes of the accidents were the breaking of wheels due to overheating."

The Louisville and Nashville Railroad Co. reported to the NTSB that it had 11 derailments since January 1977, which were caused by the breaking of Southern wheels.

"Until these wheels are replaced or adequate precautions are instituted for the operation of cars equipped with these wheels, there is imminent release of hazardous materials," said the board in its recommendation.

The board also asked that new regulations be promulgated by the FRA "to establish adequate service records so that similar wheel problems will be promptly detected in the future and corrective actions taken."

When ABC television reported as late as Tuesday that this recall action was likely, NTSB and FRA officials discounted it, saying that they had no such staff recommendations on their desk.