The U.S. and South Korea have agreed on a bilateral nuclear deal allowing the East Asian nation to expand its civil nuclear energy program, the Yonhap news agency reported on Tuesday, citing South Korean foreign ministry officials. Details of the purported deal are yet to be revealed, diplomatic sources told Yonhap.

South Korea, which is the world’s fifth-largest consumer of nuclear power, relies on 23 nuclear reactors to meet about a third of its power needs. Nearly 70 percent of its used fuel is reportedly stored in temporary facilities, many of which would reach maximum capacity by 2016.

Talks to revise the current agreement, signed in 1974, began in October 2010. The 1974 pact gives the U.S. a strong say in South Korea’s ability to enrich uranium for nuclear power generation and to reprocess spent fuel. The South Korean government has previously pushed for greater independence in using this spent fuel for peaceful purposes. However, the U.S. has expressed concerns that such a move might provoke North Korea and Japan and undermine global nonproliferation efforts.  

The new agreement would be signed at a ceremony, attended by South Korean diplomat Park Ro-byug and U.S. Ambassador to Seoul Mark Lippert, on Wednesday evening, Yonhap reported.