Radiation leak at KAERI was result of design flaws and sloppy management, regulator finds

Posted on : 2020-03-29 16:49 KST Modified on : 2020-03-29 16:49 KST
NSSC releases findings of investigation into faulty drainage system
Anti-nuclear demonstrators hold a press conference regarding a radiation leak in front of the Korea Atomic Energy Research Institute in Daejeon on Mar. 20. (Yonhap News)
Anti-nuclear demonstrators hold a press conference regarding a radiation leak in front of the Korea Atomic Energy Research Institute in Daejeon on Mar. 20. (Yonhap News)

An accidental leak of extremely low-level radioactive material that occurred at the natural evaporation facility at the Korea Atomic Energy Research Institute (KAERI) in Daejeon late last year was the result of flawed facility design and poor operations, South Korea’s nuclear regulator has found. It also discovered that radioactive waste has continued to leak over the past 30 years from the facility because of its faulty construction. KAERI is facing serious criticism for its sloppy operations over the last 30 years, not to mention its negligence of issues in facility design.

On Mar. 20, the Nuclear Safety and Security Commission (NSSC) announced that it had briefed KAERI and the Ministry of Science and ICT (MSIT) about the findings of its investigation into the radiation leak. The investigation had been launched on Jan. 21.

The fundamental cause of the radiation leak, the NSSC found, was that the drains installed for use at the facility were different from those originally approved by MSIT. A 600-liter floor drainage tank connected to external pipes had been installed in the basement of the natural evaporation facility, but that tank wasn’t part of the approved blueprints. NSSC investigators confirmed that waste had been dumped in this floor drainage tank when operations were stopped every year during the facility’s 30 years of operation, since August 1990.

Furthermore, the facility operators were unaware that the 600-liter floor drainage tank had been installed separately from the basement storage tank, which had a capacity of 860,000 liters. The operators had assumed that all the drains on the first floor were connected to the basement storage tank and that waste could therefore be poured down those drains. Every November, when operations at the facility were halted to prevent the pipes from freezing in the winter, all liquid waste was supposed to be collected in the 860,000-liter basement storage tank; but in that process, 470-480 liters of waste were poured into the floor storage tank every year after 1990, with that waste eventually leaking out of the facility.

Most of this radioactive material was absorbed by the surface of the storm drain or soil in the streams, which is why environmental surveys of radioactive levels around KAERI failed to detect anything unusual until the fourth quarter of 2019, the NSSC said. But investigators did determine that some of the 510 liters of radioactive material released by an inexperienced operator on Sept. 26, 2019, leaked outside the facility during rainfall in October and November.

Following the results of the NSSC’s investigation, MSIT plans to review what administrative measures can be taken under the Nuclear Safety Act.

Along with surveying all the facilities at KAERI that use nuclear power and radiation (there are a hundred or so) to ensure they’re in line with the building plans and permits, the NSSC has instructed KAERI to inform it of the details of its plan to carry out sweeping measures to improve facility safety. Those measures will include designating more spots at the institute to be checked for environmental radiation, updating the facility’s waste operating systems, strengthening the supervisory role of the safety management team, and hiring an outside organization to assess safety culture.

Furthermore, the NSSC plans to double the frequency of regular inspections of nuclear fuel cycle facilities, including the natural evaporation facility, and to set up a team to carry out continual on-site inspections at KAERI.

By Kim Eun-hyoung, staff reporter

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