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Original title: Fukushima nuclear wastewater diverted to the sea Expert: Pollution risk in China’s major maritime areas may be relatively low Source: China Science News
Recently, reports that the Japanese government plans to discharge the wastewater from the Fukushima nuclear power plant into the ocean starting in 2022 have sparked controversy. At a press conference on October 21, the chairman of Japan’s Atomic Energy Regulatory Commission (Regulatory Commission for short), Toyoshi Satata admitted, “This is water flowing through a damaged nuclear reactor. (We) acknowledge firmly that people will feel resistance. “He stated that it will strengthen the detection of radioactive materials in surrounding waters and publish information on the concentration of radioactive materials before and after the discharge of wastewater.
Since the 2011 earthquake and tsunami, the Tokyo Electric Power Company has collected more than 1 million tons of contaminated water from the ruins of the Fukushima nuclear power plant, and the space to store this wastewater that contains tritium has been an urgent need.
“China Science News” found in interviews and data searches that the huge volume of nuclear wastewater and the exact unknown composition of the wastewater are factors that must be carefully considered. If not handled properly, rumors will lead to “risk assessment damage.” The situation is also difficult to resolve.
This wastewater is not that wastewater
Zhang Zili, a research associate at the Chinese Academy of Sciences Institute of Electrical Engineering, told China Science Daily that wastewater discharged from a nuclear power plant operating under normal conditions can meet current discharge standards after a series of treatments.
However, considering that the Fukushima Nuclear Power Plant is in an abandoned state, the nuclear wastewater produced after its core melts is essentially different from the nuclear wastewater produced during normal operation.
“Although the reactor core is in an abandoned state, the state of the internal reagents is unknown, so the process to purify this type of cooling water is different from the general purification process,” said Zhang Zili.
If the Fukushima nuclear power plant officially discharges nuclear wastewater into the sea in 2022, the radiation in the wastewater will first go north, hit the west coast of North America and Hawaii east, and then flow to through the Philippines along the equator and finally from the Taiwan region of China. Back to Japan on the east side.
“Due to the isolation of ocean currents, the risk of radiation contamination in several important marine areas of China may be relatively low.”
Zhang Zili told China Science Daily that new procedures or treatment rules for Fukushima nuclear wastewater should be established before the official discharge.
The huge specific activity of wastewater has yet to be measured
In fact, it is one of the current common practices to discharge nuclear wastewater that meets discharge standards into the ocean.
In addition to the discharge of nuclear waste in accordance with the regulations of the International Energy Agency, the nuclear safety committees of various countries or similar organizations will supervise and review the discharge by their governments.
One of the radioactive elements in the wastewater from the Fukushima Nuclear Power Plant is tritium, which is also one of the elements that influences the possibility of discharge of wastewater into the sea.
High-level radioactive waste at nuclear power plants requires a large amount of seawater to cool down. The seawater used for cooling is activated by the released neutrons and a nuclear reaction occurs that produces tritium.
Taking the Canadian Nuclear Safety Commission as an example, the discharge activity of wastewater containing tritium has upper limits for the unit of measure and the total amount, respectively. The activity per unit mass is 106 becquerels per gram and the total activity is 109 becquerels. Your.
“China Science News” learned from the relevant nuclear science experts that a large amount of nuclear wastewater dilution and dilution and re-discharge is one of the treatment methods, but this is not feasible to some extent and belongs to ” a temporary solution, not a permanent cure. “
As far as Fukushima is concerned, the huge amount of wastewater cannot be treated in accordance with conventional operations: its existing water contaminated by radioactive substances has exceeded 1.2 million tons.
For this reason, the specific components of the wastewater to be discharged from the Fukushima nuclear power plant still need to be further verified and measured, and its specific activity still needs professional measurement and conversion.
Time is short, the task is heavy
Tritium is one of the isotopes of hydrogen and its physical half-life is 12.3 years.
The β-rays produced by it can cause external exposure to the human body, but Lan Changlin, a professor at the School of Nuclear Science and Technology at Lanzhou University, told the Chinese Journal of Science that tritium in nuclear wastewater can be absorbed. by the human body through the food chain, respiratory tract, and skin. Ingested, some of it can be converted to organically bound tritium through physical, chemical and biological effects.
“Organically bound tritium will remain in the human body for a long time due to its exchange with hydrogen in body fluids and metabolism.”
Lan Changlin said, therefore, “radiation protection must consider the impact of its biological half-drainage period.”
Among DNA macromolecules, human tissues bind to tritium and the metabolic process is very slow. Tritium can not only produce direct biological effects through the ionization of beta particles, but it can also transform the mutation mode to cause teratogenic, carcinogenic and somatic effects on the target molecules of the tissue. And genetic effects.
In 2013, Japan launched a multi-nuclide disposal facility to treat 62 types of radioactive substances in wastewater from the Fukushima nuclear power plant, but not including tritium.
According to existing technology, the means of separating tritium are complicated, expensive and time consuming.
At a press conference on the 21st, Japanese Prime Minister Yoshihide Suga stated that on the issue of nuclear wastewater treatment from TEPCO’s Fukushima Daiichi nuclear power plant, “it cannot be delayed forever.” , but a specific time or policy has not yet been set. .
As the Fukushima reactor abandonment schedule approaches, processing tasks become more urgent.
People still have many doubts about the discharge of nuclear wastewater into the sea.
Some media noted that the Tokyo Electric Power Company stated that there is no land to build new storage facilities, but there are a large number of “no-go areas” around the Fukushima Daiichi Nuclear Power Plant that are unfit for living due to to excessive levels of radiation. The Japanese side can use this vacant land to build new storage facilities. installations.
