"Obtaining a COL from the NRC does not obligate Ameren Missouri or Missouri's other electric energy providers to build a SMR at the Callway site; however it does preserve an important energy option and positions Missouri to move forward in a timely fashion should conditions be right to build a SMR in the future."Why would Ameren want to theoretically build a nuclear reactor right next to a nuclear reactor? The inexorable progress of technology. Callaway is rapidly approaching its 30th anniversary of operation; Westinghouse's SMR models benefit from advanced safety and power features that have been developed in the interim. The SMR will produce less energy than the existing Callaway plant (225 megawatts compared to 1,190 megawatts at Callaway), but the SMR is supposed to be more cost efficient to produce and safer.