The reactors, to be built at the Uljin power plant in North Gyeongsang Province, will be based on the Advanced Power Reactor (APR) design that can generate 1,400 megawatts of electricity, the Ministry of Knowledge Economy said.
"The reactors mark a turning point for South Korea's commercial nuclear energy program because no foreign-made parts are used in the most important areas," it said.
Both the man-machine interface system that helps run the power generation unit and the reactor coolant pumps were designed and manufactured in the country. In the past, such systems were imported or based on foreign design, the ministry said.
The ministry in charge of the country's industrial and energy policy said reflecting lessons learned following the Fukushima nuclear disaster in Japan last year, special safety measures have been incorporated into the design.
The government has set aside 7 trillion won (US$6.18 billion) to build the New Uljin 1 and 2 reactors located some 330 kilometers southeast of Seoul.
Construction of the New Uljin 1 unit is expected to be completed around April 2017, while the second unit will be built by late February 2018.
South Korea currently has 21 commercial reactors and has plans to build 12 new reactors by 2022 in an effort to reduce the country's dependence on crude oil, natural gas and coal.
President Lee Myung-bak hailed the new reactors as a "big milestone" in South Korea's nuclear technology history, saying the country realized the dream of building atomic reactors without relying on foreign technology in just 40 years.
During a ground-breaking ceremony for the reactors, Lee also said nuclear power has contributed significantly to South Korea's economic development and stressed that atomic power is "not an option but a must" for the energy-scarce nation.
Nuclear power is also the only viable alternative yet to fossil fuels, he said.
Lee also pledged to thoroughly investigate the cover-up of a February accident at South Korea's oldest nuclear reactor and corruption cases involving atomic power plant officials, saying such irregularities hurt public confidence in nuclear power.
In early February, the Gori-1 reactor in the southeastern city of Busan lost power for 12 minutes during a safety inspection, but it was found that officials at the power plant didn't report the incident to higher authorities until a month later.
Last month, at least three nuclear power plant officials were arrested for allegedly taking large amounts of money in bribes in exchange for using low-quality components for nuclear reactors.