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expert reaction to IAEA safety review and report on Japan’s plans to release treated water into the sea

The International Atomic Energy Agency (IAEA) have stated that their report finds Japan’s plans to release treated water stored at the Fukushima Daiichi nuclear power station into the sea consistent with International Safety Standards.


The Society for Radiological Protection, said:

“The IAEA has issued a comprehensive assessment of plans to begin discharging treated water to sea from the Advanced Liquid Processing Plant (ALPS) at Fukushima. They concluded that plans “are consistent with international standards” and that discharges will have “a negligible radiological impact on people and the environment.”

“The discharged water will contain tritium, a radioactive isotope of hydrogen, in the form of water (called HTO); all other radionuclides are almost completely removed by processing, but HTO remains in the water.

“The IAEA verdict is entirely justifiable as the discharges of tritiated water will be similar to those from Fukushima before the accident in 2011. They are also substantially less than routine discharges from some other nuclear installations, including Sellafield in Cumbria and Cap La Hague in France. Before discharge, the water will be further diluted to contain less than 1500 becquerels (Bq) of tritium per litre of water, less than the drinking water standard of the World Health Organisation – and hence considered safe to drink at that concentration. But, of course, the discharged HTO will also be massively diluted in the ocean.

“The IAEA report contains estimates of radiation doses to the most exposed individual, based on conservative assumptions about how they might ingest HTO. These doses are less than 0.01 microsieverts; that’s 100,000 times less than the dose limit for members of the public.

“As concluded by IAEA, there should be no concerns that these operations could in any way affect human health or the environment.”


Dr Mark Foreman, Associate Professor of Nuclear Chemistry / Industrial Materials Recycling, Chalmers University of Technology, Sweden, said:

“The ALPS process is a process which is able to remove the vast majority of the radioactivity from the waste water produced at the Fukushima site.  Before the water reaches the ALPS plant it has already been treated to remove cesium and strontium in either the KURION or SARRY plant.  The KURION plant uses zeolite (Herschelite) to remove strontium, cesium and some other radioisotopes from the water.  The SARRY plant uses similar chemistry to lower the radioactivity level of the water.  The water from these two plants is processed with a membrane technology of a type which is used to make drinking water from sea water.  The fresh water from this membrane plant is reused at the nuclear site while the rejected water which has a higher salt content is sent through the ALPS plant.

“In the ALPS plant a series of different solids are used to purify the water, after the ALPS process the radioactivity level in the water is much lower.  The tritium content of the water which will be released will be low, the Japanese have chosen to limit their releases to 1500 Bq per litre.  To put this in context the US limit for drinking water is 740 Bq per litre.  In 2010 the world health organization had a guideline of 10000 Bq of tritium per litre of drinking water.  So based on the US drinking water limit the water being discharged into the sea is close to that US limit.

“The projected radiation dose to members of the public from the discharge of the ALPs treated water is in the range of 0.002 to 0.030 microSv per year.  The limit for the general public for occupational radiation exposure is 1000 microSv per year.  Thus the projected dose to the general public will be very low.  By making the discharges into the sea it is likely that the risk of a large release of radioactivity from the Fukushima site will be lowered.  I reason that in the event that a tank of more highly radioactive water starts to leak the fact that there will be additional space in the tank farm as a result of the sea discharges will increase the ability of the workers to manage the problem.

“The releases of three key radioisotopes have been compared with what is naturally already in the environment, these are tritium (3H), carbon-14 (14C) and iodine-129 (129I).  The releases of these radionuclides from the ALPs treated water will not greatly increase the amount of these radionuclides in the sea.

“The global inventory of tritium, carbon-14 and iodine-129 are 2000, 1 and 0.001 PBq.  Each year the plant will release no more than 0.022 PBq tritium, the plan is to release 0.000002 PBq (2 GBq) of carbon-14 and less than 1 GBq of iodine-129 (0.03 to 0.3 GBq).  These radioactive releases will not make the world’s sea water become much more radioactive.

“For an adult who eats a lot of sea food calculations have been made for three different tanks of treated water based on the release of the water into the sea.  The doses to the member of the public from the discharges will be low.  They will be in the range of 0.0062 to 0.032 microSv per year.  To put this radiation dose in perspective a simple dental X-ray gives you a radiation dose of about 5 microSv, while a mammogram used in breast cancer screening gives you a dose of about 200 to 300 microSv.

“In Sweden the average member of the public gets a dose of about 2500 microSv per year from natural radiation sources (cosmic rays 300 microSv, natural radon gas in buildings 200 microSv, gamma rays from rocks / soil 600 microSv , potassium in people’s bodies 200 microSv and other natural radioisotopes in food and drink 200 microSv) and medical radiation uses).  The total annual radiation dose to a non smoker is about 2400 microSv per year.

“The background is lower in Japan by a factor of about ten at 330 microSv per year.

“Modern science holds the view that a radiation dose of 1000000 microSv (1 Sv) will increase your chance of developing cancer by 5 %, so if the lifetime chance of developing cancer is 30 % then a person who has had a dose of 1 Sv will have a 35 % chance of developing a cancer.  Note that radiation induced cancers are not worse, more painful or harder to treat than the same type of cancer which was caused by another reason.  For example if you develop lung cancer as a result of radiation it will be clinically the same as if it was due to some other cause.

“The radiation doses which it is expected that the general public will get as a result of the discharge to sea will be very unlikely to induce cancer in the people living in Japan.”


Prof Robin Grimes, Steele Chair of Energy Materials, Imperial College London, said:

“The IAEA have taken time and due care and attention in preparing this report, commensurate with the somewhat unique situation.  They have made it clear they will continue to monitor the release.  Independent verification is always to be welcomed.  However, the concentration of tritium, the remaining radionuclide in the water to be discharged, is very low and well below levels of any environmental concern.  The state of the tritium is important – in this case it is a component of water molecules (tritiated water) but not bound to more complex compounds.  There is no established mechanism for tritiated water bioaccumulation so discharge will further dilute these low levels of tritium enormously.  It will be interesting to see if any increase in tritium in the discharge area is even detectable over natural tritium generated by cosmic ray processes.  Certainly the concentration of tritium will be well below levels of naturally occurring radionuclides although comparing the environmental impact of different radionuclides is quite a challenge!”


Prof Gerry Thomas, former Professor of Molecular Pathology, Imperial College London, said:

“The announcement that the Japanese authorities have given permission for the release of contaminated water into the Pacific Ocean has sparked concerns both inside and outside of Japan.

“The entire process of the clean up of the water has been closely monitored by the relevant authorities inside (the NRA) and outside of Japan (the IAEA).  The latest IAEA report released today (one of many detailed reports) clearly states that the release of the stored, contaminated water is consistent with the relevant, very conservative, international standards.

“Given the above, are the concerns expressed inside and outside Japan valid?  Personally, I don’t believe so, and here is why.

“Firstly, we have to recognise that the water we drink and that circulates in our oceans is not pure.  Small amounts of radionuclide are present in drinking water, and the exact amounts can vary in different regions of the earth, depending on the composition of the soil and rock strata through which the water passes.  These include a radioactive isotope of hydrogen (tritium – 3H), a radioactive isotope of carbon, (14C), both of which are produced by the interaction of cosmic rays with elements in our atmosphere.  Radioactive potassium (40K) as well as uranium is also present in small amounts as a result of the Earth’s geology.  All of these isotopes can also be found in small amounts in the human body – we effectively co-exist with them throughout our lives.

“Secondly, it is true that man made processes also give rise to radionuclides that could contaminate our water sources.  The World Health Organisation therefore provides guidance for levels of radioactivity in drinking water.  This is set at 10,000 Bq/L, which is a very precautionary level, as there is increasing evidence that these low levels of radionuclides have no detrimental effect on our health, or affect the other creatures that inhabit our planet.  One of the side effects of the Chernobyl accident has been to produce an exclusion zone where nature flourishes, despite the radioactive contamination, simply because humans do not live there anymore.  I would submit that this provides evidence that humans are more of a risk to nature than low levels of radioactivity.

“So, is the water released from Fukushima going to pose a risk to us or to other creatures that share this Earth with us?  The water from Fukushima is being released into an extremely large body of water, the Pacific Ocean.  Anything released from the site will therefore be massively diluted.  The Japanese authorities have stated that they will dilute the water that is stored in the tanks to an activity of 1500 Bq/L before it is introduced to the ocean.  Prior to release it will therefore be at a level well below what is deemed by the WHO as a safe level for drinking water.  The radioactivity will be due almost exclusively to tritium, the only radionuclide that physically cannot be removed from the water, because it is a constituent part, being an isotope of hydrogen.

“Is this a risk to the food chain and therefore potentially to us?  There are a number of the physical and biological properties of tritium that make the answer to this question a resounding “no!”  The health effects of radiation, just like all toxins, show a relationship between dose to which our bodies are exposed and the magnitude of effect.  Put simply, a low dose of radiation is correlated with a low health effect, and once you get to very low levels, it becomes very difficult to show any health effect at all.  Identifying what is due to radiation becomes like looking for the needle in the haystack because the other factors that affect our health (diet, lifestyle etc) have a much greater influence on our health.

“Radiation dose is determined by physics, biology and chemistry.  There are a number of factors that mean exposure to tritium results in a very low dose of radiation.  Its long physical half life, (12 years) relative to its short biological half life (10 days) for tritiated water, or 40 days for organically bound tritium, means that only a small amount of radiation is released while the radionuclide transits through the body.  In addition, the low energy of its beta-radiation (-5.7 keV) which means that penetration within the body is only a few microns and therefore does little damage.

“Health effects are dependent on dose of radiation to individual tissues.  For health effects to be observed, tritium would need to be ingested or inhaled in large quantities.  Drinking 2 litres of water that was contaminated at the highest level permissible by the WHO every day for a year would result in a dose of 0.1 mSv, roughly equivalent to two weeks of natural background radiation in many countries.  Given that the level of tritium to be released is 1,500 Bq/L (1/40th of the legally permissible levels) and will be further diluted by seawater on release, doses will be several levels of magnitude lower.  Even if you were to attempt to drink excessive amounts of the salty waters of the Pacific Ocean the dose to your tissues would be insignificant.

“Some people have claimed that tritium bioaccumulates in the food chain, but there is no scientific evidence to prove this.  The Japanese authorities have carried out extensive modelling that shows that marine organisms would be exposed to less than 1/10000 of the lowest limit of the amount of radioactivity specified in the internationally agreed regulations.

“Finally, the water released will be a drop in the ocean, both in terms of volume and radioactivity.  There is no evidence that these extremely low levels of radioisotopes have a detrimental health effect.  Other substances that we willingly ingest, such as alcohol and fatty and sugary food stuffs, have a relatively large detrimental effect on our health, but are subject to much less stringent regulation and produce much less concern to the population.  Should we perhaps consider adopting the same precautionary approach to those factors?”


Prof Jim Smith, Professor of Environmental Science, University of Portsmouth, said:

“The IAEA confirmed today that the planned discharge of – still slightly radioactive – treated wastewater from the Fukushima power plant to the Pacific Ocean is in line with current international practice for such water.  The IAEA reported that the plans and processes put in place for the discharge were fit for purpose.  The Japanese methods of analysis of the wastewater prior to discharge has been evaluated by three IAEA labs as well as a number of independent laboratories worldwide.  This inter-comparison exercise found that the methods used by the Japanese were accurate.

“The planned discharge of treated wastewater containing tritium has been happening (often in much greater amounts than planned at Fukushima) at nuclear sites worldwide for many decades.  There is no evidence that such discharges cause significant damage to marine ecosystems or significant radiation doses to seafood consumers.  There is understandable concern amongst Fukushima’s fishing community about the effects this new wastewater discharge will have on the perceived quality of their produce.  Concerns about risk from seafood caught off the coast of Japan, or risk to people bathing in the sea have no basis in scientific evidence.  As long as the discharge is carried out as planned, radiation doses to people will be vanishingly small – more than a thousand times less than doses we all get from natural radiation every year.  Those who claim major risks from the wastewater discharge – without any basis in scientific evidence – should consider the negative impact of their claims on the communities affected by the Fukushima disaster.

“The IAEA has committed to continue the oversight and evaluation of the wastewater discharge process if and when it begins and for the decades-long discharge process.”

Previous comment from Prof Jim Smith on this topic, from 26 June:



IAEA press release:

IAEA report:



Declared interests

The Society for Radiological Protection: The Society for Radiological Protection is the principal independent professional body for radiation protection in the UK.

Dr Mark Foreman: “I have worked for years on advanced nuclear reprocessing, normally funded by the European Union.  I have also worked on reactor / radiation safety funded by the Swedish Radiation Protection authority (SSM) and APRI (A body funded by utility companies).  I have also worked on nuclear waste chemistry funded by both SSM and the Swedish Nuclear Waste disposal company (SKB).  I have had some training from a nuclear power using utility company, I have had the training needed to work in reactor buildings in a safe manner.”

Prof Robin Grimes: “No interests.”

Prof Gerry Thomas: “Over many years of academic life, I declare the following interests:

A member of the UK’s Committee on Radioactive Waste Disposal from 2019-2022.

Received funding from TEPCO for one visit (out of approximately 20) to Japan (can’t remember the exact date – probably around 2013).

I have worked with numerous colleagues in Japan since 2000 on research topics related to radiation, none of which have involved joint research funding.

Received funding from the Sasakawa Health Foundation of Japan for the Chernobyl Tissue Bank from 1998-2019.

Have spoken at several nuclear industry symposia, but have not received honoraria.

Have worked as an academic advisor to the IAEA on reports for Chernobyl and Fukushima.

Have advised Greens for Nuclear, but received no financial support.”

Prof Jim Smith: “I did a small (< £5k) project for Japan Atomic Energy Agency about 10 years ago and had a NERC grant 2012-2017 which was part-funded by the Nuclear Decommissioning Authority.  I don’t currently do consultancy work or have any nuclear industry links.”

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