Context: A recent simulation study by Japanese researchers using an ocean circulation model has affirmed that Fukushima wastewater release is safe.
Relevance of the Topic: Prelims: Key idea about Nuclear contamination; Key facts about Tritium.
Japan releases wastewater from Fukushima Nuclear Plant
- An earthquake followed by a tsunami in 2011 wrecked the Fukushima Daiichi Nuclear Power Plant in Japan, destroying its cooling system and causing reactor cores to overheat and contaminate water within the facility with highly radioactive material.
- Since the disaster, power plant company TEPCO has been pumping in water to cool down the damaged reactors' fuel rods. Every day the plants produce contaminated water which is stored in around 1,000 tanks, which are already filled to 98% of their 1.37 million-ton capacity.
- This water has been treated to remove most radioactive contaminants but still contains tritium (a radioactive isotope of hydrogen) and Carbon-14 which are difficult to separate from water.
- In 2021, Japan’s government announced plans to release over one million tonnes of contaminated water from the Fukushima nuclear plant into the Pacific ocean over the next 30 years.
Rationale to release wastewater
- There is a lack of available space for additional storage tanks, as well as due to safety risks and expense of managing the accumulating water.
- Japan states that the water has been treated and diluted before releasing it into the ocean. The water contains about 190 becquerels of tritium per litre, below the World Health Organisation drinking water limit of 10,000 becquerels per litre (Bq/L). (Becquerel is a unit of radioactivity).
Associated Concerns:
The release has raised concerns among China and South Korea, as well as environmental and anti-nuclear groups regarding its potential impact on public health (increase the risk of cancer), seafood and marine environment.
- Waste water released into the ocean off Fukushima will not be contained to waters surrounding Japan. It will be carried by ocean currents, particularly the cross-Pacific Kuroshio current, to other parts of the world.
- Marine animals that migrate great distances, phytoplankton (free-floating organisms) and microplastics can all act as Trojan horses to spread radionucleotides far away.
Findings of the latest Research by Japanese Researchers:
- Low radiation levels: As the nuclear facility is releasing tritiated water gradually, the Tritium levels (radiation level) is even lower than that due to natural and historical sources. The peaks from the routine discharge never exceed 0.002 Bq/L, which is 25x (25 times) lower than natural background radiation levels.
- Impact of Warming: Warmer oceans might shift the Kuroshio Current a little North and strengthen eastward flow, speeding up tritium dispersion in the mid-Pacific. However, Tritium concentrations will still remain three orders of magnitude below detection threshold.
Since, Tritium has a half life of around 12 years, natural decay reduces long-term risk. Even under extreme warming or a worst-case eddy transport scenario, the levels of the Tritium would remain undetectable across the wider Pacific Ocean by 2099.
About Tritium:
- Tritium is a radioactive isotope of Hydrogen with a half-life of about 12 years. Hydrogen has three isotopes:
- Protium- one proton and zero neutron
- Deuterium - one proton and one neutron
- Tritium - one proton and two neutrons
- Occurrence: Naturally occurring tritium is extremely rare on Earth. The atmosphere has only trace amounts, formed by the interaction of Nitrogen with cosmic rays. It can be produced artificially as a low-abundance byproduct in nuclear reactors.
- Uses:
- Energy source in radioluminescent lights for watches, gun sights, numerous instruments and tools.
- Radioactive tracer in a medical and scientific setting.
- Nuclear fusion fuel, along with more abundant deuterium, in tokamak reactors and hydrogen bombs.
- Concerns: Tritium is easily absorbed by the bodies of living creatures and rapidly distributed via blood.