The incident at YNCC's third plant in Yeosu comes as businesses brace for greater scrutiny under a new South Korean law punishing management for incidents involving worker death.
"Currently, the third plant has not stopped production and the first and second plants are operating ... as of now there is no impact to production," a YNCC official told a briefing.
"The labour ministry is on the scene to decide whether to suspend production or shut down a plant, and I think it will be decided according to administrative measures."
The incident occurred during a leak test in a cleaning process that is a procedural operation carried out every four years, the official added.
YNCC's third naphtha cracker in Yeosu, the site of the explosion, produces 470,000 tonnes per year (TPY) of ethylene.
YNCC's first and second naphtha crackers in Yeosu produce 900,000 and about 920,000 tpy of ethylene each.
YNCC's entire capacity is 2.29 million tpy, about 1.1 per cent of global capacity, Samsung Securities analyst Cho Hyun-ryul said.
"If the impact is limited to the incident site, supply disruption will not be significant," he said.
"However, a suspension order for the entire production cannot be ruled out, as stricter rules are imposed on work sites since ... the Severe Accident Punishment Act. If so, this could affect not just 470,000 but 2.29 million tonnes."
The new South Korean law, which took effect late last month, imposes criminal punishment of one or more years of jail or fines up to 1 billion won ($A1.16 billion) for severe industrial accidents on business owners and responsible management, if they violated a duty of safety measures stipulated in the law.
10°C