NEW YORK (MarketWatch) -- Two U.S. congressmen on Sunday called for a more-cautious approach to the country’s buildup of its nuclear power plants as authorities in Japan struggle to cool down plants damaged in the devastating earthquake.

Sen. Joe Lieberman, a Connecticut independent, said the U.S., “needs to quickly put the brakes on (plant construction) until we can absorb what’s happened in Japan.”

Japan braces for power outages

Authorities in Japan reported a possible, partial meltdown at one of the Fukushima Daiichi reactors that lost their primary cooling systems in Friday earthquake, then had emergency systems fail on Saturday. Authorities were filling the reactor containers with seawater in an attempt to prevent a meltdown. Late Sunday, Japanese officials reported a reactor-cooling failure at another plant, Tokai. Without proper cooling, a reactor’s nuclear fuel rods can generate such high temperatures that they melt metal walls, releasing potentially deadly radiation. See story about partial nuclear meltdown.

Lieberman, who serves as chairman of the Homeland Security and Governmental Affairs Committee, said on CBS-TV’s “Face the Nation,” that he’s been a supporter of nuclear power.

The U.S. has 23 reactors licensed in the 1960s that built under the Boiling Water Mark One design, according to a list of U.S. reactors from the Nuclear Regulatory Commission. The U.S. has a total of 104 reactors.

Some of the reactors now in focus on Japan reportedly are also boiling-water reactors built in the 1960s.

Lieberman said after the Three Mile Island accident in 1979, the U.S. revamped its safety procedures for nuclear power plants.

Power plants are required to withstand the highest-probable earthquake in each region where they’re built; the U.S. also has emergency evacuation plans in place near plants, he said.

Rep. Ed Markey, D., Mass., said on MSNBC that the plant problems in Japan amount to a “warning for us.”

He said the U.S. should not build any new plants on fault lines.

Markey said one plant design now under consideration by regulators, the Westinghouse AP 1000, is vulnerable to earthquakes.

For the past decade, the U.S. has been working to re-start nuclear power plant construction as a way to reduce use of fossil fuel and curb greenhouse gas emissions.

The U.S. has yet to issue a plant construction permit in the U.S. for a new plant, but there’s been at least one preliminary construction permit approved by regulators, according to Ivonne L. Couret, a spokeswoman for the Nuclear Regulatory Commission