Experts refuted “Wolseong nuclear power plant exposure, standard value 6/10”

Following media reports that the Wolseong Nuclear Power Plant leaked tritium (tritium), one of the radioactive materials in excess of the standard, controversy has arisen after ruling party lawmakers demanded an investigation.

In addition, members of the Democratic Party visited Gyeongju, where Wolseong Unit 1 is located for field investigation. In response, the opposition People’s Power side said, “In addition, the Democratic Party should stop investigating the Wolseong nuclear power plant and spreading systematic fake news.”

This controversy began because of a 26-page report, “The Status of Groundwater Tritium Management and Action Plan in the Wolseong Nuclear Power Plant Site,” prepared by KHNP in June of last year. In this report, it was reported that in April 2019, the tritium radioactivity level of 713,000 becquerels (Bq) per liter was measured in the water in the manhole near Wolseong Unit 3. Tritium is a radioactive isotope of hydrogen. In its natural state, it is a form in which two neutrons are attached to’normal hydrogen’, which has one proton.

Accordingly, the Korea Atomic Energy Society Nuclear Issue and Communication Committee and the Korean Radiation Defense Association held an online press conference on the theme of’Wolseong Nuclear Power Plant Tritium, Is It Really Dangerous?’ and refuted various suspicions recently raised.

The meeting was attended by Professor Yong-Hoon Jung of the Department of Nuclear and Quantum Engineering at KAIST, Jae-Gi Lee, Director of the Research Institute for Radiation Safety and Culture, Professor Hee-Ryeong Kim of the Department of Mechanical Aerospace and Nuclear Engineering at the Ulsan Institute of Science and Technology (UNIST), and Professor Gun-Wook Kang of Seoul National University Medical School. The contents of their presentation are organized by issue.

“As a result of urinary investigation of 495 residents around Wolseong from 2014 to 2015 by requesting a specialized agency, the amount of exposure was about 0.6 microsieverts (µSv) per year, which was 6/10,000 of the legally permitted standard of 1mSv. In the second survey from November 2018 to July 2020, the exposure amount was about 0.34µSv per year, which was 3.4/10th of the legal limit. 0.6µSv is one-83th of 50µSv exposed during chest X-rays. Professor Jeong Yong-hoon said, “Compared to the exposure from food, it is the same as the amount of exposure when eating 6 bananas per year.” Sv is a unit representing the amount of radiation affecting the human body.”

“In the state of staying in the water collection well (manhole) in the drainage ditch of the turbine building of Wolseong Nuclear Power Plant Unit 3, the concentration of tritium was up to 713,000 becquerels per liter. Becquerel is the amount of radiation emitted per second. However, when diluted and released to the outside, the concentration is about 13 becquerels, which is insignificant compared to the emission standard of 40,000 becquerels. The 40,000 bacrel per liter is applied when discharging water from a nuclear power plant to the outside, and water accumulated inside the site is not applicable.”

“Tritium is a radioactive isotope that releases weak beta particles, and energy cannot penetrate the skin outside the body. When absorbed into the body, it is distributed throughout the body and discharged in urine. There are no reports of tritium-induced cancer. In animal studies, cancer has also been induced in mice exposed to more than 500 microsieverts. The exposure of residents near the Wolseong nuclear power plant is insignificant at 0.34 to 0.6 microsieverts per year.”

“Spent nuclear fuel is managed in a three-stage facility. It is composed of a storage tank on the third floor, a water shield on the second floor, and a catchment well on the first floor. Water is collected from the first floor sump, measured concentration and quantity, and sent through a drain pipe. An epoxy liner (membrane) is installed in the storage tank to prevent water leakage. At this time, the concentration of tritium is finally diluted to decrease the concentration and then discharged to the outside. The concentration of discharged water is measured separately.”

“The Korean Nuclear Safety Commission and the US Nuclear Regulatory Commission (USNRC) have an emission standard of 40,000 barrels per liter. However, the Canadian Nuclear Regulatory Commission is 7,000 barrels, and the Australian Atomic Radiation Safety Agency standard is 9000 barrels. The reason why standards differ from country to country is that the water to which the standards are applied is different. Korea and the United States are based on discharged water, and other countries (organizations) are based on drinking water or raw water from water purification plants. Also, the radiation dose target for calculating the concentration is different. Korea and the US are based on the annual allowance of 1mVs, while other countries are adopting 0.1mVs.”

“Tritium also comes from nature. It also occurs a lot in cosmic radiation entering the earth from space. The amount of tritium produced by cosmic radiation is about 0.06 exabecral (EBq) per year. 1 EBq is an amount equivalent to a 100 kilogram bacrel Artificial tritium is also found in military luminous products. Tritium is present in all of the water we encounter today.”

Daejeon = Reporter Kim Bang-hyun [email protected],kr