WASHINGTON (Reuters) - The U.S. Department of Energy’s nuclear security office is developing a project to help other countries handle nuclear waste, an effort to keep the United States competitive against global rivals in disposal technology, according to two sources familiar with the matter.

FILE PHOTO: A technician looks at the pool storage where spent nuclear fuel tanks are unload in baskets under 4 meters of water to decrease temperature as part of the treatment of nuclear waste at the Areva Nuclear Plant of La Hague, near Cherbourg, western France, April 22, 2015. REUTERS/Benoit Tessier/File Photo

The push comes as the United States struggles to find a solution for its own mounting nuclear waste inventories amid political opposition to a permanent dump site in Nevada, proposed decades ago, and concerns about the cost and security of recycling the waste back into fuel.

The National Nuclear Security Administration is considering helping other countries by using technologies that could involve techniques such as crushing, heating and sending a current through the waste to reduce its volume, the sources said.

The machinery would be encased in a “black box” the size of a shipping container and sent to other countries with nuclear energy programs, but be owned and operated by the United States, according to the sources, who asked not to be named because of the sensitivity of the matter.

“That way you could address a country’s concerns about spent fuel without transferring ownership of the technology to them,” said one of the sources.

The NNSA confirmed a project to help other countries with nuclear waste is underway but declined to provide details.

“We are in the conceptual phase of identifying approaches that could reduce the quantity of spent nuclear fuel without creating proliferation risks - a goal with significant economic and security benefits,” NNSA spokesman Dov Schwartz said.

The effort is being led by NNSA Deputy Administrator for Defense Nuclear Nonproliferation Brent Park, a nuclear physicist and former associate lab director at the Energy Department’s Oak Ridge National Laboratory, appointed by President Donald Trump in April.

The NNSA declined a Reuters request for an interview with Park.

The sources did not name countries to which the service would be marketed, or where the waste would be stored after it is run through the equipment. But they said they were concerned the processes under consideration could increase the risk of dangerous materials reaching militant groups or nations unfriendly to the United States.

Former President Jimmy Carter banned nuclear waste reprocessing in 1977 because it chemically unlocks purer streams of uranium and plutonium, both of which could be used to make nuclear bombs.

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The NNSA’s Schwartz said the plans under consideration do not involve reprocessing, but declined to say what technologies could be used.

The sources familiar with the NNSA’s deliberations said there are three basic ways that the physical volume of nuclear waste can be reduced, all of which are costly. At least one of the techniques poses a security threat, they said.

The first, called consolidation, reduces the volume of nuclear waste by taking apart spent fuel assemblies and crunching the waste down to two times smaller than the original volume – an approach that is considered costly but which doesn’t add much security risk.

A second technique involves heating radioactive pellets in spent fuel assemblies. The process, which gives off gases that must be contained, results in a waste product that has more environmental and health risks.

A third approach called pyroprocessing - developed at the Department of Energy’s Argonne National Laboratory - puts spent fuel in liquid metal and runs an electric current through it. That reduces volume, but concentrates plutonium and uranium – making it a potential proliferation risk.

The nuclear community is divided on whether pyroprocessing fits the definition of reprocessing.

The Trump administration has made promoting nuclear technology abroad a high priority, as the United States seeks to retain its edge as a leader in the industry, amid advancements by other nations like Russia, and France – both of which already offer customers services to take care of waste.

U.S. reactor builder Westinghouse, which emerged from bankruptcy in August and is owned by Brookfield Asset Management BAMa.TO, hopes to sell nuclear power technology to countries from Saudi Arabia to India, but faces stiff competition from Russia's state-owned Rosatom.

U.S. Energy Secretary Rick Perry visited Saudi Arabia this month for talks on a nuclear energy deal with the kingdom, despite pushback from lawmakers concerned about the killing of journalist Jamal Khashoggi in the Saudi consulate in Istanbul.

MOUNTING U.S. STOCKPILES

The United States is also struggling to support its own nuclear industry at home, with aging reactors shuttering, new projects elusive due to soaring costs, and an ongoing political stalemate over a permanent solution for mounting nuclear waste stockpiles.

The United States produces some 2,000 metric tons of nuclear waste each year, which is currently stored in pools or in steel casks at the nation’s roughly 60 commercial nuclear power plants across 30 states.

The federal government designated Nevada’s Yucca Mountain as the sole permanent U.S. nuclear waste repository decades ago to solve the problem, spending about $13 billion on the project, but it has never opened due to local opposition.

Thomas Countryman, the State Department’s top arms control officer during the Obama administration, said the government should make headway on the domestic problem before helping other countries.

“The primary issue on this front … is not that the U.S. can’t offer a low-volume option to potential buyers; rather it’s that the U.S. still has no option for disposing of its own spent fuel,” he said.

Edwin Lyman, a nuclear expert at the Union of Concerned Scientists, said NNSA should be less concerned about volume of waste and more concerned about the dangers that make it hard to store.

“It’s not the volume of the nuclear waste that’s the issue, but the radioactivity and heat it gives off as well as the fact that it remains dangerous for hundreds of thousands of years,” he said.