Yet another halt to U.S. nuclear expansion plans was announced last week as the twin new reactor projects at the South Texas Nuclear Project were put on hold. The two reactors were due to start construction in 2012. But this now looks doubtful. Ironically, embattled Japense utility, Tepco, was to be an investor in the project along with NRG Energy, the majority owner, which was even looking for loans from the Japanese government.