The explosion took place in Hyundai Heavy Industries’ submarine under construction on Tuesday, according to a local media outlet MoneyToday.
According to the report, the explosion occurred at the submarine at HHI's plant located in Ulsan on Monday morning. The fire was suppressed in 30 minutes and there was no casualty.
The explosion reportedly took place during the process of extracting remaining gas in hydrogen tank installed in the submarine. A local submarine does not generally use nuclear energy as motive power but hydrogen fuel cells are installed in the tank instead.
"We are not able to disclose which type of submarine had the explosion accident," said the company's official, adding, "There will no problem in meeting the construction schedule."