The Nuclear Regulatory Commission is expected to issue a construction permit Tuesday for TVA to build a 300-megawatt system at its Clinch River site in Tennessee, west of Knoxville, according to a media alert from the company. TVA is considering as many as four of the BWRX-300 reactors from GE Vernova Hitachi Nuclear Energy, though this permit is only for the initial system, confirming a report last week by Bloomberg News.