Story highlights The shutdown will put an "unprecedented" strain on power supply, authorities say

The two reactors are halted because they are using unverified parts

The government says there is no risk of a radiation leak from the parts in question

Nuclear power is under increased scrutiny worldwide after the Japanese crisis

South Korea said Monday that it had shut down operations at two nuclear reactors after discovering that they were using parts supplied with forged quality certificates.

Halting the reactors to replace the parts will result in "an unprecedented level" of strain on the nation's power supply as it heads into the winter months, the Ministry of Knowledge Economy said in a statement.

The controversy over the products used in the Korean reactors comes amid increased scrutiny of nuclear power worldwide following the crisis at the Fukushima Daiichi nuclear plant in Japan during the aftermath of the earthquake and tsunami that hit the country in March 2011.

The unverified parts in South Korea are products like fuses and power switches that don't pose a risk of causing a radiation leak, authorities said.

The plant operator, Korean Hydro & Nuclear Power Co., found that eight suppliers had sold it a total of 7,682 items with forged quality certificates between 2003 and 2012, according to the government. The total value of the products was around 820 million won, or $750,000.

The vast majority of those parts that were put into use went to two reactors at the Yonggwang Nuclear Power Plant in the southwest of the country, the government said. Those are the two reactors that are being shut down until at least the end of the year in order to replace all the unverified items.

The two reactors account for about 5% of South Korea's national power supply, according to the government. Their suspension will significantly reduce the amount of energy supply that South Korea holds in reserve each day during January and February.

Temperatures in areas of South Korea regularly drop well below freezing in the winter months.

The government has called on relevant agencies to enact measures this month to counteract the expected pressure on the power supply from the shutdown of the reactors.