Science or politics? That is the question that needs to be answered regarding the proposed shutdown of the Yucca Mountain nuclear waste repository in Nevada, which is backed by President Barack Obama and Senate Majority Leader Harry Reid, D-Nev.

For the past month, the world has been watching efforts in Japan to stabilize four nuclear reactors crippled by an earthquate and tsunami one-two punch, and the desperate efforts to contain radiation from spent fuel rods stored in cooling pools. With the nuclear crisis in Japan focused more on spent fuel than the actual reactors, attention in the United States has turned to the issue of spent fuel storage.

With no central respository in the U.S., spent nuclear fuel is being stored in cooling pools at the 104 nuclear plants scattered around the country. Most experts believe, and the crisis at the Fukushima Daiichi nuclear plant in Japan demonstrates, this poses serious risks.

Despite nearly three decades of planning and development, plus nearly $15 billion in federal expenditures at Yucca Mountain, the project was suddenly scrapped in the past two years. The administrations of the last four presidents supported Yucca Mountain. Why the sudden policy reversal?

Last week, Republicans in the U.S. House of Representatives decided to find the answer to that question and called for an inquiry into the Yucca Mountain decision. Rep. Shelley Berkley, D-Nev., calls the proposed GOP probe a “political stunt.”

But Americans should know if Yucca Mountain is being abandoned as a nuclear waste storage site because of politics — with Reid as head of the Senate and Obama possibly looking for votes in Nevada or working some kind of deal with Reid.

Is Yucca Mountain being shut down because of science or politics? If it’s science, why did it take nearly 30 years and billions of taxpayer dollars to come to the conclusion that this remote location is not an appropriate site?

If Obama and Reid want to shut down Yucca Mountain, why are no alternative sites being proposed?

Republicans are asking for documents and written answers to submitted questions regarding the decision to shut down the proposed nuclear storage facility.

Even before hearings begin, it’s troubling to learn that a former staffer for Reid has been installed as the chairman of the Nuclear Regulatory Commission. With Reid strongly opposed to Yucca Mountain, this key appointment appears to be a way for Reid to extend his influence to the NRC, which must decide if it will resume work at Yucca Mountain, extending the 25-year effort and adding to $14 billion spent developing the site.

A central repository is not wihout risks or challenges, such as transporting nuclear waste to the site. Still, most experts believe a central storage facility is safer than storing 70,000 tons of radioactive waste at 104 reactor sites not designed for long-term storage — and located within 50 miles of tens of millions of Americans.

Americans should know the full story of the Obama administration’s plans to mothball Yucca Mountain. The burden is on the White House to prove that science, and not politics, is behind the decision — and to offer a good alternative.