Complex sentence: However, critics point out that Shippingport was smaller than most commercial nuclear power plants; most reactors in the United States are about 1,000 MWe, give or take a few hundred megawatts, while Shippingport was only 60 MWe.
Split into simpler sentences: However, critics point out that Shippingport was smaller than most commercial nuclear power plants. In the United States, most reactors are about 1,000 MWe give or take a few hundred megawatts, while Shippingport was only 60 MWe.