Last year's closure of the Kewaunee Power Station in Wisconsin sent shock waves though the American nuclear industry, not because the reactor suffered an accident, but because it could not withstand something more potent - market forces.

So two months ago, the industry launched a promotion campaign called Nuclear Matters, whose aim is to create a greater appreciation of atomic power's role as a reliable source of carbon-free electricity.

"I think most Americans aren't sensitive to the fact that nuclear energy is going through challenging times," Evan Bayh, a former Democratic senator from Indiana, told a roundtable discussion Monday at the Constitution Center sponsored by the Greater Philadelphia Chamber of Commerce.

Bayh and former Sen. Judd Gregg, a Republican from New Hampshire, were enlisted as the bipartisan cochairmen of Nuclear Matters, whose purpose is to start a dialogue that will lead to improvements in the nuclear business climate.

Nuclear power accounts for 19 percent of the nation's electricity generation, but the industry is challenged by a slow-growth market in which electricity prices are depressed by cheap energy from the shale-gas boom and a flood of tax-subsidized wind power.

Bayh said reactors were not adequately compensated for providing carbon-free electricity and nearly uninterrupted power compared with intermittent renewable sources.

"We all benefit from that, but it's not factored into the price today," he said.

The campaign bills itself as "a cross-section of individuals, organizations and businesses." Monday's session was attended by U.S. Sen. Pat Toomey (R., Pa.), utility officials, labor and business leaders, and nuclear-power academics from Pennsylvania State University and the University of Pittsburgh.

"We use a lot of electricity, and we're very interested in keeping it abundant and reliable and inexpensive," said participant John B. McGowan Jr., chief executive of GasBreaker Inc., a Malvern manufacturer of gas safety valves.

The campaign already has attracted opposition from antinuclear activists. The Nuclear Information and Resource Service has denounced Nuclear Matters as an industry "front group."

Exelon Corp., the nation's largest nuclear fleet operator and owner of Peco, wrote the initial check to fund the campaign.

Exelon declined to disclose the amount of its funding, but Christopher Crane, the company's chief executive, said in an interview last week that Exelon was "very supportive" of the effort.

Gregg, the Nuclear Matters cochair, said that New England faced the need for more fossil-fuel generation in the aftermath of Entergy Corp.'s decision to close the Vermont Yankee Nuclear Power Station later this year.

"Basically, people just expect their energy to be there," said Gregg. "By the time it's not there, it's going to be too late to correct it."

Bayh downplayed the effect of the 2011 Fukushima nuclear accident in Japan as undermining public confidence, citing strong support in areas surrounding reactors.

"You look at polling, scientific polling, and for most people, safety is not a concern," he said.

But McGowan, the Malvern manufacturer, cautioned the industry about becoming too comfortable with polls. He said his sense is that there is an underlying apprehension with safety that needs to be addressed.

He encouraged the industry to "hit pretty hard" to reinforce the safety message, much as the natural-gas industry has done with its campaigns to counteract fears of hydraulic fracturing, or fracking.