The United States is expected to continue to ban South Korea from nuclear reprocessing and enrichment under a soon-to-be-announced nuclear cooperation agreement but is expected to allow Seoul to conduct a kind of experimental reprocessing for research purposes, U.S. experts said Monday.

After more than four years of negotiations, Seoul and Washington are now close to announcing a revision to their 1974 nuclear energy cooperation pact, known as the "123 agreement." The agreement has centered on banning the South from enriching uranium and reprocessing spent fuel in exchange for U.S. technological assistance.

The main sticking point in the negotiations has been Seoul's demand that it be allowed to undertake enrichment and reprocessing activities, just as Japan is allowed to do so under a U.S.-Japan nuclear cooperation agreement. But Washington has been reluctant about Seoul's demand due to proliferation concerns.

Considering Washington's concerns, Seoul has demanded that it be allowed to use "pyroprocessing," a reprocessing technology that poses fewer proliferation risks because it leaves separated plutonium mixed with other elements.

On Monday, Duyeon Kim and Mark Hibbs, researchers at the Carnegie Endowment for International Peace, said in a report that the envisioned agreement will allow South Korea to "carry out the first pyroprocessing stage, called electroreduction, as research and development."

"The United States does not want South Korea to enrich and reprocess. But it is not asking Seoul to adopt the so-called gold standard, which would require South Korea to legally renounce these techniques in the agreement text, as was the case with the United Arab Emirates and Taiwan," the researchers said in the report.

That means that the new agreement is expected to make no provision for South Korea to enrich or reprocess, but it will not foreclose this possibility for the future, they said.

The 1974 pact had been scheduled to expire in March last year, and Seoul and Washington launched negotiations to revise it in 2010. But after failing to find a compromise, they extended the existing pact to March 2016 to buy more time for negotiations.

Widespread views are that the two countries are expected to hold their last meeting on the issue to conclude the agreement later this month. (Yonhap)