Environment: Society: News: Hankyoreh

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Political battles are hot when reports such as Wo reported that groundwater at the site of the Wolseong nuclear power plant in Gyeongsangbuk-do was contaminated with tritium (tritium) and that Korea Hydro and Nuclear Power is in the process of confirming this and taking measures. The conservative opposition argues that it is an exaggeration and distortion of public opinion by the ruling party and environmental groups trying to divert interest in nuclear power plant investigations to radioactive leaks. Some pro-nuclear experts say that the spilled tritium has a human impact of only 6 bananas and 1 gram of anchovy. On the other hand, the ruling party and environmental groups are calling for a joint public-private investigation, arguing that the opposition to the post-nuclear policy is conducting nuclear power politics as a hostage for the safety of Gyeongju citizens. The main issues and facts were summarized.

Cover of Korea Hydro & Nuclear Power’s report on the status and action plan of groundwater tritium management in the Wolseong nuclear power plant site

On January 13th, a member of the Democratic Party’s Environment Special Committee and the National Assembly-related standing committee held a press conference at the National Assembly Communication Hall, saying, “Tritium is an artificial radioactive material produced during nuclear fission.” The expression “tritium does not exist in nature” was used in the distribution material. As this information became known, criticism came out that Democrats did not confirm the basic facts. This is because tritium also exists in nature. Tritium is not only produced by artificial fission, but also when high-energy particles from space enter the Earth and collide with the atmosphere. Microscopic amounts exist in the atmosphere and sea water. It is also present in the human body and soil.

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However, the concentration of tritium detected around the Wolseong nuclear power plant was significantly higher than the national average. Seoul National University’s Ph.D. dissertation’Application of 3H and 7Be as a Tracer of Atmospheric Water Vapor and Particles Tracking Atmospheric Water Vapor and Particles Using 3H and 7Be’ (Jeong-Seok Chae, 2019), observed at 15 national measuring stations in Korea as of 2006. Tritium averages 1.05 Bq per liter (becquerel). From 1998 to 2015, the amount of tritium detected in atmospheric water vapor around the Wolseong nuclear power plant was 100 to 1000 times higher than this. In fact, according to the KHNP tritium report, the amount of tritium in the rainwater from the groundwater piping system in the Wolseong nuclear power plant site was measured at 130-1000 Bq per liter. Originally, there were a lot of tritium around the nuclear power plant, but the Wolseong nuclear power plant is said to be particularly numerous. Baek Do-myung, a professor at Seoul National University’s Graduate School of Health, said, “The concentration of tritium measured around the Wolseong nuclear power plant is higher than that around nuclear power plants in Japan, France, and Hungary.”

<한겨레>KHNP’s report on the management status and action plan of groundwater tritium in the Wolseong nuclear power plant site previously reported byIn April last year, KHNP detected 713,000 Bq of tritium per liter in the manhole of the groundwater drainage ditch (turbine gallery) under the turbine building of Wolseong Nuclear Power Plant Unit 3 in April of last year. The ditch is not a planned route for the release of radioactive materials. 71 million becquerels is a high concentration, 17.8 times that of 40,000 becquerels per liter set by the Nuclear Safety Commission as an external emission standard. As a result of the operation of the groundwater monitoring program by KHNP, from August 2019 to May, just before the report was prepared, tritium with the highest concentration of 8610 Bq/L was detected in the groundwater under the Spent Nuclear Fuel Storage Tank (SFB) of Wolsong Unit 3. 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. The KHNP side is highly likely to have recognized the possibility of groundwater contamination by tritium as early as 2013 and at the latest in 2017. According to the KHNP report, tritium was detected in 2013 at a similar level to the recent one 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. In the observation boat (WS-2) near Unit 2, the figure once rose to 28,200 Bq/L. However, only in May of last year, Han Suwon formed a’tritium issue special team’ to respond 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.

Conservative media and conservative opposition parties argue that tritium exists in bananas and anchovies over the fact that high concentrations of tritium were found in places that should not be leaked. On the 8th, Professor Jeong Yong-hoon of KAIST’s Department of Nuclear and Quantum Engineering wrote on his Facebook page, “The amount of tritium exposure of residents living around the Wolseong nuclear power plant is at the level of eating 6 bananas or 1 gram of anchovies per year.” Potassium in bananas and anchovies releases beta rays (radioactivity) like tritium, which is compared with the exposure of tritium. The exposure to residents mentioned by Professor Jeong refers to the results of the’tritium impact assessment of residents around the Wolseong nuclear power plant’ in 2015 by a private environmental monitoring organization commissioned by Dongguk University’s Department of Preventive Medicine, Chosun University’s Department of Nuclear Engineering, and Korea Atomic Energy Research Institute. At that time, the amount of tritium produced most from the bodies of residents around the Wolseong nuclear power plant was 28.8 Bq/L. When expressed in radiation dose, it is 0.0006mSv (millisievert), which is 0.06% of the annual standard radiation dose to the public of 1mSv.

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However, it is not appropriate to compare tritium with potassium in bananas or anchovies in the same line. Potassium easily escapes from the body, but tritium is converted into carbohydrates through metabolic processes, and it is combined with tissues in the body such as DNA, which can cause damage to the body continuously. If the effect of potassium is temporary, the effect of tritium can last for a long time. Prof. Domyung Baek said in a conversation with “Unlike potassium that moves without being attached to the body, tritium can be a component of DNA or other associations in the body. If tritium is bonded to D&A and then splits, other substances other than hydrogen come to the place, causing damage.”

Of the 24 nuclear power plants in Korea, only Wolseong 1~4 in Wolseong, Gyeongju is a heavy water reactor. Heavy water reactors use natural uranium, unlike light water reactors that use enriched uranium as nuclear fuel. During operation, nuclear fuel must be replaced, and heavy water with low neutron loss is used as moderator and coolant, not ordinary water (hard water). Therefore, if radiation management is neglected, the area around the site may be contaminated with tritium. Among domestic nuclear power plants, the safety concerns of the Wolseong nuclear power plant are particularly greater. Because tritium is small, even thick iron plates penetrate through the gaps of iron atoms. For this reason, it is pointed out that the 1mm thick epoxy coating, which is currently painted for waterproofing in the spent fuel storage tank, should be replaced with a 6mm thick stainless steel plate like other nuclear power plants in Korea.

Heavy water channels are also vulnerable to earthquakes. Unlike light water reactors in which fuel rods containing nuclear fuel are vertically erected, heavy water reactors have fuel rods lying on their side. Nuclear fuel exchangers weighing 10 tons are hung on both sides of 380 fuel rods lying on their side in a state of high temperature and high pressure in the Wolseong nuclear reactor. As a result, it is more susceptible to earthquake motion. In preparation for an earthquake that will come once every 100 years, the Wolseong nuclear power plant site applied the maximum ground acceleration (the speed at which the ground moved during the earthquake) 0.1g (gravitational acceleration). However, 0.12g was measured in Wolseong during the Gyeongju earthquake in September 2016 (scale 5.8 on September 12). It has exceeded the design criteria. At the time, the maximum ground acceleration was 0.4g at the Ulsan Observatory, which was about 8 km away from the epicenter. Since then, it has been pointed out that the seismic design standards of nuclear power plants should be raised, but no clear measures have been taken for Wolseong nuclear power plants. The KHNP report shows that the concentration of tritium in the Wolseong nuclear power plant site increases after the actual earthquake in Gyeongju. Lee Jung-yoon, CEO of the Nuclear Safety Division, said, “At the time, a detailed investigation is needed on the possibility of disruption of underground structures due to earthquakes, but KHNP focuses only on monitoring and is ignoring measures to block leakage at the source.”

Wolseong Nuclear Power Plant Unit 1 in Yangnam-myeon, Gyeongju-si, Gyeongbuk. By Gyeongju/Lee Jeong-ah, staff reporter [email protected]

There is a village called Naari on the south side of the Wolseong nuclear power plant site. The distance between the town hall and the site of the nuclear power plant is only 800m. Up to 470 Bq/L of tritium was detected in a well at the border of the site closest to the village. The observation boat at the northern end of the site reached a maximum of 924 Bq/L. On the other hand, the concentration of tritium in groundwater measured last year at Bonggil-ri, a village north of the nuclear power plant, was only 8.81 Bq/L. It is difficult to rule out the possibility that high-concentration tritium, with a difference of more than 100 times, is spreading out of the site boundary through groundwater. Civic groups in the Gyeongju area demand that Naari and other nearby villages and the sea be inspected for contaminated water discharge. The cause of the outflow of tritium-contaminated water should be identified and countermeasures should be prepared for this unplanned outflow. Song Joo-hee, an activist at the Energy and Climate Bureau of the Federation of Environmental Movements, said, “A transparent and fair investigation should be conducted through a joint public-private investigation group in which various actors, not limited to the KHNP and regional interests, participate.” By Park Ki-yong and Kim Min-je, staff reporter [email protected]