Environment: Society: News: Hankyoreh

There is a tsunami evacuation sign on the beach in front of the 1st Wolseong nuclear power plant in Gyeongju, Gyeongsangbuk-do. By Gyeongju/Lee Jeong-ah, staff reporter [email protected]

The fact that the groundwater at the site of the Wolseong nuclear power plant in Gyeongju was extensively contaminated with tritium (tritium), a radioactive material, was revealed by Korea Hydro & Nuclear Power’s own investigation. It has been confirmed that KHNP reported that underground piping and spent nuclear fuel storage tanks were the main sources of tritium contained in groundwater, and was pursuing measures such as facility replacement and repair. Tritium is Controversy over contaminated water at the Fukushima nuclear power plant accidentIt is a radioactive material that causes internal exposure in the human body and is known to cause genetic mutation. The release of radioactive material by a route not specified by nuclear power plants is not permitted under the nuclear law. The possibility that the tritium, which was confirmed to be leaked this time, was detected at a high concentration in the groundwater observation well installed at the boundary of the nuclear power plant site, and spread to the outside of the nuclear power plant cannot be excluded. Nevertheless, KHNP and the Nuclear Safety Committee did not apply the’public disclosure’ rule, saying, “All of the observation boats are located inside the nuclear power plant area and cannot be regarded as’emission to the environment’, which is an external leak under the Nuclear Act.” It is also not aware of the size of the spill. According to the report of KHNP’s’Groundwater Tritium Management Status and Action Plan’ of the Wolseong Nuclear Power Plant site obtained on the 23rd, KHNP reported 71 per liter of water standing in the manhole of the groundwater drainage ditch (turbine gallery) under the turbine building of Wolseong Nuclear Power Plant Unit 3 in April last year. Only 3,000 Bq (Becquerel) of tritium was detected. The ditch is not a path for radioactive material discharge. The 710,000 becquerel is a high concentration of 17.8 times the management standard (40,000 Bq/L) set for dischargeable drainage channels set by the Nuclear Safety Commission. As a result of operating the groundwater monitoring program by KHNP, tritium with the highest concentration of 8610 Bq/L was detected in the groundwater under the Spent Nuclear Fuel Storage Tank (SFB) of Wolseong Unit 3 from August last year to May, just before the report was written. During the same period, up to 26,000 Bq/L of tritium was produced from the groundwater under the spent nuclear fuel storage tank of Unit 2, and up to 39700 Bq/L of the groundwater under the spent nuclear fuel storage of Unit 1. ‘Unplanned release’ that does not go through planned exhaust and drainage from nuclear power plants is a violation of the operational technical guidelines under the Nuclear Act, regardless of concentration. This is because surveillance and management are not performed, so it is impossible to assess the impact on the environment and residents around the nuclear power plant. It is highly likely that Wolseong Nuclear Power Plant recognized the possibility of groundwater contamination by tritium as early as 2013 and at the latest in 2017. According to the KHNP report, in 2013, tritium was detected at similar levels as recently in some observation boats, including the groundwater observation well (SP-5) installed near Wolseong Unit 3. At that time, researchers at KHNP’s Central Research Institute raised the need to respond by investigating cases of groundwater contamination caused by the unplanned discharge of nuclear power plants abroad. From the beginning of 2017, concentrations have risen significantly in some observation wells near structures with high risk of groundwater contamination. On the observation boat (WS-2) near Unit 2, it once climbed to 28,200 Bq/L. However, only in May of last year, Han Suwon formed a special team for tritium issues and started responding in earnest. It is difficult to avoid pointing out that the original security committee has not yet established standards for reporting and management of unplanned releases, so it is a prolonged response. In this regard, KHNP admits the existence of the report, but maintains the official position that “no unplanned leak has been confirmed so far.” He said, “Because of the nature of heavy water reactors, the concentration of tritium in the nuclear power plant site is relatively high compared to the surrounding area, but no leakage has been confirmed to date.” As a countermeasure against groundwater pollution caused by tritium, KHNP replaces underground pipes and installs spent nuclear fuel storage tanks, wastewater storage tanks (SRT), liquid waste tanks (LWT), etc. that collect resins that adsorb and remove radioactive substances from cooling water. Measures to inspect and repair have been promoted. This measure means that these facilities are viewed as sources of groundwater discharge for tritium. These facilities are like a swimming pool installed underground, and are structured with waterproof treatment inside a concrete tank that is over 1m thick. It is inevitably more susceptible to damage from aging than other nuclear power plants installed with metal materials.

The location of the main groundwater observation network within the Wolseong nuclear power plant site where tritium was detected. Display in Google Earth

Experts who reviewed the KHNP report say that tritium should not only leak out as a damaged part of the facility, but also pay attention to the possibility of seeping through the facility. This is because tritium, unlike gamma nuclides such as cesium or technisium, is particularly small and penetrates through the gaps of iron atoms even on thick iron plates. In fact, in nuclear fusion research using deuterium and tritium as fuels, preventing contamination of the reactor metal through this process has become one of the main tasks. On the premise of anonymity, one nuclear power plant expert said, “If it comes out through a crack, large gamma nuclides should be detected.” In view of it, we have no choice but to suspect leakage by infiltration.” As pointed out, if tritium is seeping through infiltration, it is not easy to solve the problem. Another nuclear power plant expert said, “It is impossible to fundamentally prevent the emission of tritium while leaving the structure of the old nuclear power plant saturated with tritium for a long time. If a problem is identified through an investigation at the level of digging and dismantling the reservoir, The waterproof epoxy coating needs to be replaced with a stainless steel plate.” Although cost is also an issue, it is a difficult measure to apply while the nuclear power plant is operating. Tritium has exceeded the limit of the U.S. Atomic Energy Regulatory Commission (NRC) (740Bq/L) (740 Bq/L) and up to 1320 Bq/L in all five groundwater observation wells installed at the northwest boundary of the nuclear power plant site of Units 1 and 2 since 2013, when KHNP started the investigation. Was detected. The site boundary observation boat (SP-11) about 450m north of the spent nuclear fuel storage tank of Unit 1 also produced a maximum of 924 Bq/L. It is a high concentration of more than 100 times the highest concentration of 8.81 Bq/L among groundwater measured at Bonggil-ri, Yangbuk-myeon, Gyeongju-si near the nuclear power plant during last year’s environmental radiation investigation by Kyungpook National University’s Radiation Science Research Center. Local denuclearization movement groups, which encountered the results of the detection of high concentration of tritium in the observation well at the boundary of the nuclear power plant, are demanding countermeasures, saying that it is clear that tritium contamination may have spread outside the site boundary considering the mobility of groundwater. Lee Sang-hong, executive chairman of the Post-Nuclear Gyeongju Citizens’ Joint Action Committee, said, “It is easy to check whether it has spread outside the nuclear power plant by installing a groundwater observation well outside the boundary area where tritium was detected, but the KHNP and the ROK were not released to the environment (outside) without such efforts. It is not convincing to conclude that it is not,” he said. “We will have to check whether the environment is released as soon as possible and take measures such as pollution control.” Senior reporter Kim Jeong-soo [email protected]