The design of a South Korean-developed nuclear reactor has passed a preliminary review by the U.S. nuclear watchdog, officials said Wednesday, raising hopes for final approval that would pave the way for exports to the United States and elsewhere.

The U.S. Nuclear Regulatory Commission will now conduct a full examination of the APR1400 reactor to determine whether to certify its design, South Korea's state power operator, Korea Hydro & Nuclear Power, said in a statement.

APR1400 is a next-generation reactor model that South Korea developed for 10 years from 1992. Compared with the previous Korean-developed reactor, OPR1000, the new model has larger capacity and longer lifespan and costs less to generate power.

In 2009, South Korea signed a contract to export the new reactors to the United Arab Emirates.

The U.S. watchdog introduced the preliminary review system for reactor design last year, and APR1400 is the first reactor model subject to the review. APR1400's passage raised the possibility of its final approval, the statement said.

The final review is expected to take about 42 months, officials said.

An NRC certificate for a reactor's design is considered something of a guarantee of its safety. Should APR1400 win the certificate, it is expected to help South Korea export the new reactor not only to the U.S., but it would also be a boon for exports to other countries, too, the company said.

Demand for nuclear reactors in the U.S. is expected to grow because the operating licenses for many reactors are scheduled to expire in the next 10 to 20 years. In exporting reactors to the U.S., an NRC certificate is considered a precondition, officials said.

"The NRC's launching of the main review (for APR1400) not only laid a foothold for expanding to the U.S. market, but also demonstrated to the world the excellence of South Korea's reactor design. It is expected to raise the brand value of the Korean nuclear reactor and breathe vitality into reactor exports," the company said in the statement.

South Korea, the world's fifth-largest nuclear power user, is seeking to become a new export powerhouse of nuclear power plants.

Following its export of a light reactor to the UAE, the first of its kind, Seoul has been aggressively tapping into the Middle East, where oil-rich countries are trying to diversify their energy sources.

During South Korean President Park Geun-hye's visit to Saudi Arabia, the two nations on Tuesday signed a memorandum of understanding to pave the way for a $2 billion project to build two mid-size commercial reactors in the kingdom, which plans to install up to 18 nuclear reactors by 2040.

Despite its expanding overseas bid, however, South Korea's nuclear industry is facing growing pressure at home over mounting safety concerns after Japan's Fukushima disaster in 2011, at a time when several aging atomic facilities are nearing their retirement.

In late February, South Korea's nuclear watchdog faced strong protest when it extended the operation of a 32-year-old nuclear reactor until 2022, the first heavy-water reactor to receive an extension of its life span.

There are 23 reactors that generate one-third of the power in South Korea. The operational licenses of six of those reactors are set to end in the next decade.