Fukushima FAQ

general FAQ in development

Fukushima Daiichi Nuclear Reactor

What is the Fukushima Daiichi Nuclear Power Plant?

The Fukushima Daiichi nuclear power plant experienced a partial core meltdown in 2011 as a result of tsunami waters that reached 15 meters high (49 feet), pouring in over the reactor’s facility walls after a 9.0+ magnitude earthquake in the Pacific. The seawater that overwhelmed the Daiichi nuclear power plant took out the necessary power supplies to cool the reactors, causing partial meltdowns in three of the six reactors. In contrast to the Daiichi plant, which had been operated by the Tokyo Electric Power Company (TEPCO), a similar coastal plant – the Onagawa Nuclear Power Station operated by the Tohoku Electric Power Company – further north and closer to the epicenter, was instead able to act as a safe haven for locals needing power and shelter. The events at Fukushima have resulted in an ongoing environmental and public health crisis.

What are the radioactive concerns from Fukushima?

Radioactive fuel was once responsible for heating water into steam, generating electricity from spinning turbines at the nuclear power plant. Once the integrity of the containment of these radioactive materials was breached due to uncontrolled heating in the core, contamination erupted over several days in multiple explosive events. The Japanese government established an evacuation zone surrounding the plant, as the risks of contamination spreading in the air and through seawater were yet to be determined. Sea water was initially used to cool the melted-down radioactive material, which bored holes into the ground beneath the reactor housing units. Over the next decade, TEPCO and the Japanese government have since been responsible for containing the radioactive material, including water that has been used to cool the still heat-and-radiation-producing fuel.

The wastewater at Fukushima is produced when naturally occurring rain and groundwater, as well as coolant water, combine with man-made highly radioactive nuclear fuel containing materials, called corium, buried at the nuclear plant. Normal reactor operations have radiation concerns to a smaller degree on significantly shorter time scales; spent fuel rods are cooled in massive pools and under typical conditions do not release contaminants to the degree seen at Fukushima. The partial meltdown in Japan resulted in an open system, where water can enter naturally from the ground and rain, and then exit full of radioactive material into the environment. Its containment is physically managed with underground barriers, but the remaining radioactive core material must be consistently cooled to maintain its level of radioactivity and heat production until the waste can be managed and disposed of. The International Atomic Energy Agency (IAEA), is a global regulatory authority overseeing the long term waste management plan.


What is ALPS Treated Water?

Coolant water used in all nuclear reactors is irradiated, which creates tritium as well as some activated corroded metal in the structure materials which is collected in the water. The direct exposure of water to hot corium, a sometimes lava-like nuclear-fuel-containing material, greatly increases the presence of tritium and other radioactive material. The extensive contamination present at Fukushima necessitated the development and use of the Advanced Liquid Processing System (ALPS) treatment. ALPS water is treated in an extensive series of water purification stages to reduce the concentration of radionuclides in the wastewater to levels acceptable by the IAEA, for disposal into the ocean, monitored by the IAEA. ALPs treated water also has other nuclear contaminants, discussed later in the FAQ.

Before the controversial decision to release ALPS water into the ocean was reached, the Japanese government made efforts to store the treated wastewater in now over a thousand 1000 ton tanks, resulting in millions of gallons stored on land. The limited space and ongoing need for cooling are limiting factors, the IAEA has determined the level of treatment and purification processes sufficient for disposal into the ocean. The risk was determined to be lower for ALPS water dispersed in the ocean than for the potential of ALPS water and its contaminants spilling onto Japanese soil and soaking deep into the groundwater.



What have been the radiation impacts from Fukushima?

The primary impacts from radiation from Fukushima are local. For Japanese people, many that once lived in the surrounding region are hesitant to return home. Evacuation orders have been or are being lifted in Futaba, Okuma, and Namie, but citizens still do not flock back. Working fishermen cannot engage in trade with neighboring China as a result of international radiation concerns banning procurement of Japanese fish. Deaths directly contributed to radioactive release from Fukushima are difficult to track, as many workers and residents sue for compensation as a result of evacuation orders, illnesses and cancers, and suicides. There has been one reported worker death due to radiation from exposure during the Fukushima Daiichi incident, though he and many of the workers were very likely heavy smokers, and no non-worker deaths attributed to radiation as of 2024. The Japanese government has assumed responsibility and accountability for the costs of the nuclear materials clean-up, and TEPCO has been committed to take care of all sickness and death of workers at Fukushima Daiichi. They will pay for any cancer deaths of the thousands of workers.



How does the dose from Fukushima’s wastewater compare to the natural background dose?

The oceanic radiation release from Fukushima poses international concerns against the tritium and other radionuclides present in ALPS water. According to dose estimates, the human exposure dose from the treated water discharge is approximately 1/70,000 to 1/5,000 of natural radiation exposure, fractions of the background dose which averages around 2.1 mSv/year (“mili-Sievert”, a dose measuring unit of radioactive energy absorbed per gram of material) in the rest of Japan. The release into the ocean is expected to have minimal additional, if any, biological and environmental health effects, with exposure doses considered to be negligible fractional additions to the background doses. The activity of the releases remains well below IAEA imposed dose limits; the dose from tritium and the present additional radionuclides is estimated between 0.0000062 mSv/yr and 0.000032 mSv/yr, compared to typical ranges of global background exposures of between 2-4 mSv/yr.

Is tritium naturally occurring, and where else is it found?

Tritium is a naturally occurring radioactive isotope. It is a form of hydrogen with two additional neutrons in its nucleus, making it a heavier and radioactive (unstable) variant of the hydrogen atom. When cosmic background radiation, ionizing electromagnetic waves that originated in space, hits gasses in our upper atmosphere, a nuclear reaction takes place which produces gaseous tritium. That tritium becomes a part of the air and makes up some amount of the hydrogen in water, H2O. Tritium has a natural abundance of 10^-18, contributing only 10s of Becquerels (radioactive decays per second) from inside our body naturally as we consume water. While tritium is naturally present in trace amounts in the environment, its concentration is measurably increased by human activities, particularly nuclear power generation and weapons testing.

After ALPs treatment, tritium from Fukushima is released into the ocean at levels 1/7th that of the maximum concentration recommended by the World Health Organization (WHO) for drinking water.


The table above links to a comprehensive report published by the Canadian Nuclear Safety Commission (CNSC) in January 2008. It outlines the regulatory framework, research findings, and international comparisons related to tritium levels in drinking water. While tritium is naturally occurring, the focus on its release from Fukushima highlights the complex considerations involved in managing radioactive contaminants resulting from human activities.

Is water naturally radioactive?

Water is naturally radioactive due to gaseous tritium making its way into the water cycle. Trace elements and radioisotopes occur in the environment as a result of radioactive decay chains from uranium and thorium in rock. The aforementioned tritium adds additional dose to water as it picks up trace elements throughout its terrestrial life. Some radioactive isotopes have half-lives of billions of years, so we perpetually detect some concentrations of them dating back to before the formation of Earth. We have co-evolved alongside the presence of radioactive elements and radioactive water, it is as natural as anything else on Earth is.

Is Tritium release unique to Fukushima? How does the tritium release from Fukushima compare to other sources of tritium?

The tritium releases at Fukushima are orders of magnitude smaller than this collection of reported releases at other nuclear power plant and operating facilities. Tritiated water is a regular release in the typical operations of nuclear systems.

What makes tritium unique in the context of radioactive contamination?

The tritium release from Fukushima presents a unique challenge in the realm of radioactive contamination. What sets tritium apart in the realm of radioactive contamination is its dual nature as both a naturally occurring element and a byproduct of human activities. Managing its release entails a delicate balance between determining its natural presence and mitigation of potential environmental impacts from too-elevated levels of contamination. Tritium in water cannot be easily filtered out.

Man-made tritium removal is also uniquely challenging because, as a heavier form of hydrogen, is chemically indistinguishable from other forms of water, it is chemically the same H in H2O whether in the form of tritium or hydrogen. The oceanic tritium releases at Fukushima are diluted away from the Japanese coast as it moves into the deep ocean, maintaining a low level of added radiation concentrated at the release site, dispersing further into the ocean.


Is tritium the only radioactive material in the water that is being released?

Irradiated nuclear material travels into millions of gallons of water as they come in contact beneath the nuclear power plant. The contaminated water is pumped to fill storage containers near the Fukushima facility for treatment. ALPS treated water has additional trace quantities of radionuclides. An IAEA report  detected a majority of “134Cs, 137Cs, 60Co, 125Sb, 106Ru, 90Sr, 129I, plus tritium, 14C and 99Tc,” which is not all of the contaminate. This shortened list was compiled after removal of isotopes with exceedingly short half-lives or activities below 1 Bq in the samples measured. Ingestion of some isotopes of iodine, strontium, selenium, and plutonium pose larger risks than that of tritium, but are stated to be in negligible concentrations.

The IAEA methodology sampled water from several tanks, and determined the highest dose impacts to be from three pathways of exposure: ingestion of local seafood that lived in a marine environment with radioisotopes presence, ingestion of seawater while swimming, and seaspray on the skin. The dose estimates of the water releases consider the presence of the additional non-tritium radionuclides. The highest impacted group is considered to be high seafood intake Japanese locals who live near the region of waste water releases, as they experience the largest concentration of radionuclides off their coast.

How does the dose from the Fukushima water releases compare to the dose we are exposed to naturally, particularly considering other radioactive elements like K-40?

In assessing the dose from the Fukushima water releases, it’s crucial to contextualize it with our natural background radiation exposure. One key element in this comparison is potassium-40 (K-40), a naturally occurring radioactive isotope present in our environment. K-40 is present in bananas, with a natural abundance of .0117%, far less than 1% of all potassium in nature. If a single banana is considered to have a half gram of potassium. We maintain our bodies’ required level of potassium and other essential nutrients through our diet, which include radioactive isotopes. For instance, a single banana may have an activity of about 15 Bq, and when consumed will contain a dose of .1 uSv. A micro Sievert is 1 million times smaller than a Sievert, .1 uSv is 2,000 times smaller than the average background dose of Japan.

The average healthy person in the U.S. receives about 3.6 mSv of dose per year from various sources, with 82% of this exposure coming from natural sources. Radon, a colorless gas and a natural product of radioisotopes in the Earth, contributes significantly to this exposure. Additionally, cosmic rays ( the cause of natural tritium), radioactive materials in the food chain, and terrestrial sources, play roles in our natural radiation exposure. The most significant additional source of exposure is through medical imaging, which can contribute as much as an additional 2-3 mSv depending on individual medical needs. 3.6 mSv falls within the 2-4 mSv level of global natural background doses. The additional dose locally released at Fukushima is estimated to be 1/5000 of the average background dose in Japan, 2.1 mSv, with some variation.

What ongoing monitoring is being done?

Radwatch plans to include a page with live-updating measurements of the ALPS water release, stay tuned!