South Korea Wednesday struck a deal with the United States for the start of full-fledged research into a new technique for spent nuclear fuel recycling that could greatly reduce concerns over storage shortage.

Seoul also opened the way to produce low-enriched uranium, a boost to its pursuit of a stable supply of nuclear fuel.

After more than four years of negotiations, the two sides struck a 21-point deal that calls for bilateral cooperation based on the "principles of equality and reciprocity." according to the foreign ministry officials.

Under the deal, the U.S. will consider actions to assist "storage, transportation and disposal" of spent fuel by South Korea, they added.

It will replace the existing nuclear accord, signed in 1974, which strictly bans Seoul from engaging in reprocessing and uranium enrichment activities.

"The new deal will open an era of new nuclear cooperation between South Korea and the United States," Park said in a comment released by her spokesman Min Kyung-wook in Chile, where she is on a three-day state visit. She said she is "pleased with" the deal.

In the agreement, South Korea has secured long-term advance consent from the U.S. for early stages in experimental reprocessing, called "Pyroprocessing," including "Post-irradiation examination" and "Electro-reduction."

South Korean officials characterize pyroprocessing as "recycling" spent fuel, while it has yet to be commercialized.

Pyroprocessing is said to have less chance of being converted into a program to produce nuclear weapons as it leaves separated plutonium mixed with other elements.

The agreement will allow South Korean scientists to conduct research into the untested technology at existing local facilities.

Besides, Seoul will be able to push for a low-enrichment program through consultations with Washington.

The allies have decided to establish a high-level standing commission to consult on the sensitive issue, with the U.S. represented by its deputy secretary of energy and South Korea its vice foreign minister.

After signing the agreement, U.S. Ambassador to Seoul Mark Lippert described it as "reciprocal."

"It respects each other's sovereignty and it enhances our shared leadership on civil nuclear issues," he stressed in a statement.

Amb. Park Ro-byug, who led Seoul's negotiations, also said the deal would pave the way for "advanced and reciprocal" cooperation.

"Since South Korea and the U.S. have established a system for strategic and forward-looking cooperation in the nuclear energy sector, the alliance is expected to strengthen further," he told reporters.

The deal, coupled with pages of agreed minutes, stipulates that South Korea has an "inalienable right" to the peaceful use of nuclear energy as signatory to the Treaty on the Non-Proliferation of Nuclear Weapons.

It added the Seoul-Washington nuclear partnership will be the "cornerstone" of the global nuclear nonproliferation regime.

The agreement will remain in force for 20 years with the two sides to extend it for five years if both wish to do so.

South Korean officials said their country will be able to expand its non-military nuclear program, as it tries to increase nuclear plant exports.

Park also said the deal will give a big boost to South Korea in pursuing foreign markets for export of nuclear reactors.

"It is meaningful that we have opened the pathway for uranium enrichment, albeit not in the foreseeable future," a senior foreign ministry official said on background. "Related criteria and procedures have been made. Industrial and technological considerations will be among key factors."

The ministry will discuss with other related authorities to decide whether the National Assembly's approval of the deal is required, he added. (Yonhap)