A federal appeals court signaled today that it might force the Nuclear Regulatory Commission to spend all its existing money allocated to the proposed construction of a nuclear waste dump at Yucca Mountain, Nev., before the agency can cite lack of funds in suspending its consideration of the project. A major sticking point for the three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit appeared to be the fact that the agency still has $10.4 million to spend on the project.