The construction of two reactors in the US using Lego-style modular parts has met with major difficulties, casting doubts over the efficacy of the innovative building method and its viability for the nuclear industry in future.

Southern Co’s Vogtle plant in Georgia and SCANA Crop’s VC Summer plant in South Carolina are building new reactors for the first time in over a decade, both of which are AP1000 models designed by Westinghouse Electric Co. The individual modules of the AP1000 reactor can weigh hundreds of tons and can rival…