Nuclear reactors generate 20 percent of the electricity in the United States and 15 percent in Wisconsin. More important, they account for more than 60 percent of the nation’s — and 70 percent of Wisconsin’s — low-carbon power.

The nation is far too reliant on coal-fired plants whose emissions contribute not just to climate change and mercury contamination but also to heart and lung diseases. Despite the damage, coal plants still generate about 45 percent of the nation’s and 60 percent of Wisconsin’s electricity.

Other energy sources face challenges, too. Natural gas is a cleaner-burning fuel, but its extraction through fracking causes environmental damage. Wind and solar power are promising alternatives and deserve to be a growing part of the nation’s energy portfolio, but neither has reached the scale or economic efficiency needed to reverse climate change.

Yet without significant research and development in the next generation of technology, nuclear power will decline. The Chicago-based Exelon Corp. recently announced plans to shut down two nuclear plants in Illinois next year, citing the failure of state lawmakers to pass a bill that would extend state subsidies for the plants. Three years ago, Wisconsin’s Kewaunee Power Station shut down.

In a bipartisan vote earlier this year, Wisconsin lawmakers lifted a moratorium on construction of nuclear reactors in the state. It was a welcome recognition of the role that nuclear power can play in creating a safe, secure and reliable energy portfolio. Congress can now further the cause nationally by investing in advanced nuclear technology.