A shipment of plutonium from Japan arrived Monday at a South Carolina nuclear site, despite objections from Gov. Nikki Haley to her state being used as storage for such materials.

In a news release, the National Nuclear Security Administration confirmed that 331 kilograms of plutonium had arrived at the Savannah River Site near Aiken. Federal officials also said that a shipment of highly enriched uranium has also been transferred to the Y-12 National Security Complex near Oak Ridge, Tennessee.

Savannah River Site Watch, a watchdog group that monitors activity related to the site, had estimated the plutonium would arrive in South Carolina last month. The shipment consists of plutonium supplied to Japan in the 1960s and 1970s for nuclear reactor research purposes.

Haley, whose office did not immediately respond to requests for comment Monday, has a long-running dispute with the federal government over the long-term storage of nuclear materials. Earlier this year, she demanded that U.S. Energy Secretary Ernest Moniz stop or reroute the shipment, writing, "It is imperative to the safety of our citizens and our environment that South Carolina not allow this to happen. ... God bless."

About a week after that letter, Haley claimed victory when Moniz told her that 6 metric tons of plutonium stored at the site would ultimately be permanently stored at a New Mexico facility that is slated to be up and running later this year. The shipment that arrived Monday is part of that amount.

Tons of plutonium have accumulated over the years at the former nuclear weapons complex, where a facility to process such materials into commercial nuclear reactor fuel, as part of a nonproliferation agreement with Russia, remains incomplete. South Carolina is already suing the federal government over what the governor has called its broken promise to the state to finish the mixed-oxide fuel facility, which is billions over budget and behind schedule.

Because the facility wasn't operational by a Jan. 1 deadline, the federal government was supposed to remove 1 metric ton of plutonium from South Carolina or pay fines of $1 million a day for "economic and impact assistance" — up to $100 million yearly — until either the facility meets production goals or the plutonium is taken elsewhere for storage or disposal.

The lawsuit, filed in federal court in February, seeks the daily fines and removal of the plutonium.

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Kinnard can be reached at http://twitter.com/MegKinnardAP . Read more of her work at http://bigstory.ap.org/content/meg-kinnard/