As the worst nuclear crisis in Japan's history unfolds dramatically and replaces the initial shock and awe unleashed by last week's devastating earthquake and tsunami there, South Koreans are now turning a wary eye to their own nuclear energy policy.

Radiation leaks from damaged reactors at a crippled nuclear power plant in the Japanese province of Fukushima are believed to have affected up to 190 people in the region, and tens of thousands of residents were evacuated to avoid potential exposure to radiation.

The ongoing nuclear debacle in the neighboring country only a two-hour flight away is raising fresh questions in South Korea about safety of domestic nuclear power plants.

South Korea operates 21 nuclear reactors, which supplies around 40 percent of electricity here, and is currently searching for sites to construct more down the road. The first one was built in 1978, after South Korea had to shift its attention from thermal power to an alternative energy source after the two oil shocks of the 1970's.

The country also aims to become one of the top exporters of nuclear reactors and nuclear technology. The ambitious project of exporting 80 nuclear reactors worth 400 billion U.S. dollars by 2030 has gotten off to a propitious start, with the country signing a lucrative deal last year to build and operate four nuclear reactors in the United Arab Emirates.

President Lee Myung-bak, who happens to be a somewhat unlikely advocate of green growth, has thrown all his weight behind the nuclear drive. Nuclear energy, except for its most vocal critics, has been generally considered in South Korea as a reliable energy source that does less damage to the environment under right circumstances.

Now that the nuclear nightmare is on full display in neighboring Japan, however, those long critical of South Korea's growing reliance on atomic power are galvanized into action.

"The accident in Japan has reminded us what a delusion it is to believe there actually is such a thing as a safe nuclear power plant, and how helpless we humans are when faced with a natural disaster," progressive civic groups and environmental activists said Monday during an anti-nuclear rally in front of the government complex in downtown Seoul.

"The South Korean government must stop its policy of expanding the production of nuclear power," the activists, including those from Green Korea United, the Democratic Labor Party and Energy Justice Actions, said in a joint statement. "Stop sugarcoating the policy as (past of) green growth initiatives."

Recent research findings has repeatedly shown South Korea is by no means earthquake-free. Four reactors at the Wolsong nuclear power plant are built on active faults, rendering them especially vulnerable to potential earthquakes, environmental activist in the southern industrial city of Ulsan said in a recent statement.

With the Korean peninsula surrounded by sea on three sides, many nuclear reactors built along the coast are prone to tsunami threats, they added. "Renouncing South Korea's energy policy that depends too much on nuclear power should be the only fundamental solution to all these problems," said the activists from Ulsan, a city only 20 kilometers away from two major nuclear power plants.

Opposition lawmakers followed suit. "South Korean nuclear reactors can resist up to 6.9-magnitude earthquakes, but considering various factors including frequency of occurrence of earthquakes in northeast Asia, an earthquake-resistant design should be enhanced," Jeon Hyun-hee, spokeswoman of the main opposition Democratic Party, said Tuesday.

"The Lee Myung-bak administration should reconsider its nuclear energy policy. Safety must be the first and foremost priority," she added.

Still, the South Korean government remains unfazed, saying that the killer earthquake and tsunami that ravaged Japan has had no impact on nuclear plants here.

The government argues radiation leaks from Japan are not likely to affect South Korea. The amount of radiation detected at the country's easternmost island of Ulleung, the closest to the troubled Japanese nuclear plant, remains at a usual level. Wind direction, a key factor in deciding where and how far leaked radiation will travel, is still unlikely to bring released radiation to South Korea, according to officials.

The Korea Institute of Nuclear Safety is currently operating a 24-hour situation room to keep a closer eye on the related development.

The government, citing experts, claims superiority of South Korea's pressurized water reactors (PWR), which has separate cooling systems, to boiling water reactors (BWR) such as those at the stricken Fukushima plant.

It also cites the fact that five earthquakes of around 5.0- magnitude to hit South Korea since 1978 have left the country largely unscathed, dismissing perceived urgency of rethinking the nuclear energy landscape. The official recording of earthquake here began in 1978.

At the same time, the government project of becoming a major exporter of nuclear reactors is not likely to go down the toilet anytime soon.

President Lee pledged Monday in the United Arab Emirates that South Korea will build "world-class" nuclear reactors in the Middle Eastern country. South Korean-made reactors will be safe and efficient, he reportedly said.

And the first thing he said after returning to Seoul? "It is important that the public understands our nuclear reactors are safe," local broadcaster SBS quoted Lee as saying.