South Korea plans to build two new nuclear reactors within the next 15 years in an effort to revive its nuclear power footing for energy, the government announced Monday.

The addition will increase the number of reactors to 39 by 2029. Currently, Korea has 23 reactors nationwide.

The expansion of nuclear power is included in the seventh “basic plan for long-term electricity supply and demand,” which covers the period between 2015 and 2029.

The Ministry of Trade, Industry and Energy had developed the biannual power supply plan to set the energy mix of the country’s power sources by 2029 and submitted it to the National Assembly on Monday for approval.

The energy plan also calls for the withdrawal of a proposal to build four coal-fired power plants under the sixth power supply basic plan to help further reduce the country’s greenhouse gas emissions.

“Giving up additional coal-powered plants was an unavoidable choice to raise the ratio of environmentally friendly energy sources in the energy mix to meet the growing power demand and in line with Korea’s Post 2020 Climate Change Mitigation Commitments,” a MOTIE official said.

The latest power supply plan projected the country’s demand to increase 2.2 percent per year on average over the next 15 years, reaching 656,883 gigawatt-hours in 2029.

“We will also raise the ratio of renewables, like solar and wind power, and natural gas in the energy mix but those clean energy sources are still too expensive to become stable clean energy sources, replacing nuclear power, in resource-poor Korea,” the official said.

The post-2020 regime is a new international agreement sought by the United Nations that will set each of its member’s own commitments to cutting greenhouse gas emissions.

South Korea is expected to submit its own report before the end of September.

The government has yet to reveal its voluntary commitments, but the latest power supply plan suggests the country will boost its use of clean and renewable energy.

With the proposed changes in the country’s power sources, nuclear power plants will account for 28.5 percent of the overall power supply, in terms of generation capacity, in 2029. The figure compares with 27.4 percent under the sixth basic plan announced two years ago.

The proportion of fossil-fuel power plants, on the other hand, will be lowered from 34.7 percent to 32.2 percent, while that of clean, renewable energy sources will rise from 4.5 percent to 4.6 percent, the ministry said.

The seventh power supply plan, however, faces opposition from civic groups.

“We are very surprised that the ministry consider nuclear energy as a clean energy source,’’ Lee Yong-kyung from Energy Justice Actions said, adding that nuclear energy is not a cheap energy source considering the cost of construction and compensation.

“The time is ripe for Korea to prepare for a transit to renewables, not to set it aside due to cost issues.’’

By Seo Jee-yeon, news reports (jyseo@heraldcorp.com)