Kai Ryssdal: The nuclear power story detoured briefly to Chernobyl today. At a meeting in Ukraine marking the 25th anniversary of that disaster, donor nations promised another $780 million to help build a new radiation containment shell at the site.

Crews at the Fukushima plant in Japan have started pumping highly radioactive water out of the basements of one of the damaged reactors. Officials say it could take nine months to fully shut things down.

But once that problem’s taken care of, Japan’s going to have to deal with another dilemma, as Sarah Gardner reports from the Marketplace Sustainability Desk.

Sarah Gardner: Before the Fukushima disaster, Japan had plans to almost double its nuclear capacity. That meant a full half of the country’s electricity would come from nuclear power someday. It was all part of a national plan to cut global warming emissions.

But that vision is now in doubt. James Lucier is with the research firm Capital Alpha.

James Lucier: I suspect that the credibility factor, the deep damage to the Tokyo Electric Power Company’s credibility in particular, is going to forestall any serious decisions about building nuclear power plants for quite some time.

Lucier says in the short- and medium-term, the country has no choice but to rely on energy sources that spew greenhouse gases. He says that primarily means importing liquid natural gas and gas turbines.

Lucier: Given the immense reconstruction effort underway in northern Japan, they don’t have time, they don’t have resources to build other types of power plants.

Natural gas plants can be built quickly and General Electric and Siemens are already offering to supply the equipment. But if Japan ever phased out its nuclear reactors completely, an analysis in Forbes calculates the country’s carbon footprint would grow 10 percent over current levels. One carbon analyst says it’s not clear if Japan’s overall emissions have shot up since the earthquake. One factor limiting those emissions, she says, is a fall in economic activity along with demand for electricity.

I’m Sarah Gardner for Marketplace.