The reactor, often referred to as the 'heart' of a nuclear power station, usually requires maintenance every 18 months. During this ...
The reactor, often referred to as the 'heart' of a nuclear power station, usually requires maintenance every 18 months. During this period, the lid is opened to replace the nuclear fuel and perform inspections. Correctly opening and closing the reactor head (lid) is essential during the maintenance process because of the potential for radioactive leaks. The technology used to tighten and loosen numerous bolts arranged closely around the 5-meter-diameter circular rim of the reactor head is considered the 'jewel' of nuclear plant maintenance. Even a slight misalignment or uneven tightening of a single bolt can significantly increase the risk of radioactive leakage.
Only three companies globally manufacture equipment based on this technology, with one being a South Korean company. Mujin Giyeon has localized the 'SST (Single Stud Tensioner)'—a device that tightens bolts individually—and the 'MST (Multi Stud Tensioner)'—a machine that tightens multiple bolts at once. A stud is a specific type of bolt used to secure the reactor lid, while a tensioner is a machine that pulls and tightly fastens the bolt. One-third of domestic nuclear power plants and the UAE's Barakah Nuclear Plant, South Korea's first exported nuclear facility, utilize this company's equipment.
Cho Sung-eun, 66, the CEO of Mujin Giyeon, met at the company's headquarters in Gwangsan District, Gwangju, on the 6th, stating, "To avoid radioactive leaks, advanced technology is required to evenly tighten 54 bolts, each measuring 2 meters, under pressure 400 times greater than that of tap water." He further mentioned, "We have localized equipment that was previously controlled by Germany, and last month, we successfully established an export route to India's nuclear power plants, surpassing German firms." The Korea International Trade Association also recognizes it as "a company that has broken into a highly challenging market." Sales increased from 16.2 billion South Korean won in 2022 to 24.6 billion won last year.
◇ From 'Mechanic' to 'Nuclear Operator'
Cho, originally from Muan, South Jeolla Province, completed his studies in mechanical engineering at Chosun University and spent 12 years working as a 'metal-cutting technician' at a company that produced lathes, a type of machine tool. In 1989, after gaining confidence in his technical skills, he chose to launch a business focused on custom parts manufacturing. He initiated sales by sending letters that read, "If your company has an issue, we can create anything for you. Even small peripheral components are welcome." During this period, he had the chance to visit the Hanbit Nuclear Plant in Yeonggwang, South Jeolla Province. Cho remarked, "This is it!" He was certain that nuclear energy would shape the future of the energy sector.
At first, he obtained contracts for small facilities, like turbine supports for nuclear power stations and debris filters required to pump seawater used for cooling. Later, he came across the SST. During that period, nearly all equipment used for tightening reactor lids was imported from Germany, and no local company had tried to produce it domestically.
He began development in 2000 but encountered numerous difficulties. Following almost three years of work, the equipment failed to gain approval from Korea Hydro & Nuclear Power. Cho looked for an opportunity overseas. He attended a German nuclear equipment fair and handed out company brochures, which resulted in a contact offering to place an OEM (original equipment manufacturing) order. Cho stated, "I convinced Korea Hydro & Nuclear Power by saying, 'The German company we've imported from is now asking us to handle their orders. Can't you trust us now? We're 20% cheaper.'" Eventually, he managed to obtain the business.
◇ Now Looking Ahead to the Future of the Nuclear Industry
Mujin Giyeon successfully adapted the MST, which involves simultaneously and uniformly tightening and loosening multiple bolts according to the SST. The MST, which requires more advanced technology, took over ten years of research to be acknowledged and secured its initial supply contract with Korea Hydro & Nuclear Power in 2021.
Cho is now concentrating on upcoming developments in the nuclear industry. The company is broadening its operations to encompass small modular reactors (SMRs), management of spent nuclear fuel, and the market for decommissioning nuclear power plants. It intends to boost investments in manufacturing casks—extremely durable special containers weighing 120 tons each for secure transportation and storage of spent nuclear fuel—and SMR parts. Mujin Giyeon is exploring partnerships with the U.S. nuclear firm NuScale Power, which is intensifying its SMR investments, and is constructing a 1,000-pyeong (about 3,300 square meters) 'SMR-specific factory' in Mokpo, South Jeolla Province.
