select search filters
roundups & rapid reactions
before the headlines
Fiona fox's blog

expert comment on release of waste water from Fukushima into the Pacific

It has been announced that the Fukushima nuclear plant will start releasing treated radioactive water into the ocean from the 24th August.

These comments accompany an SMC Briefing.


Prof Paul Leonard, Fellow of the Society for Radiological Protection and a Chartered Radiation Professional, said:

“Nuclear power stations are licensed to operate within specified limits that are based on international standards in terms of radiological risk. The proposed discharge of tritium from Fukushima is being undertaken under suitable conditions and in radiological terms, the environmental impact on the public and seafood is negligible. Appropriate seafood monitoring should continue to be undertaken to provide reassurance.”


Comment sent out by our colleagues at SMC New Zealand:

Dr David Krofcheck, Senior Lecturer in Physics, University of Auckland, said:

“The release of currently filtered cooling water containing tritium atoms from the Fukushima plant will not cause physically detrimental effects. Tritium is produced naturally as part of our normal environmental background radiation, and it travels via rain or rivers into the world’s oceans.  The water release is designed to have seven times less tritium per liter than is recommended for drinking water by the World Health Organization.  Much more tritium has been released by normally operating nuclear power plants into the North Pacific Ocean since those plants in China, South Korea, and Taiwan, were first located on coastal sites.  

“In contrast, the presence of cancer-causing nuclear fission isotopes cesium-137, strontium-90, and iodine-131 should be checked before the initial batch of water is released. These isotopes, deposited into the Fukushima waters during and shortly after the 2011 disaster, are responsible for the radioactivity in seafood, and the subsequent fishing bans.”


Prof Tom Scott, Professor of Materials and academic lead for Sellafield UK Centre of Expertise for Uranium and Reactive Metals, University of Bristol, said:

“From my viewpoint this indeed the technically correct decision.

“Other alternatives were examined, such as borehole injection, continued storage etc. but ultimately this is a situation where the actual quantity of tritium being discharged per litre of water, is incredibly low and hence the risk posed to the environment and people is incredibly low. When released into the Pacific, the tritium is further diluted into a vast body of water and would quickly get to a radioactivity level which is not discernibly different from normal sea water.  Hence, it poses very little risk and the risk itself decreases with time due to the relatively short radioactive half life (12/3 years), meaning that the amount of tritium (and hence the risk) continually reduces.

“A key point to remember is that sea water already contains small amounts of tritium. Tritium is produced naturally in small quantities in the upper atmosphere, and gets into the oceans through rainfall, with some of the atmospheric tritium also being residual from nuclear weapons testing (see 6 (

“For me, this is a classic instance where the perceived risk posed by the tritium is radically higher than the actual (or true) risk posed.  This is partly due to poor communication as well as poor education.”


Comments sent out by our colleagues at SMC Australia:

Associate Professor Tony Hooker is Director of the Centre for Radiation Research, Education and Innovation at The University of Adelaide:

“I would like to reiterate that the release of tritium from nuclear facilities into waterways has and is undertaken world-wide with no evidence of environmental or human health implications.  I welcome the news about the impending release and support Japan’s decision to commence disposal and believe they have a robust radiation management plan that has been approved by the IAEA, the Japanese NRC as well as other radiation protection agencies world-wide.

“I think with the likely comprehensive independent monitoring of the environment to occur around the release site of Fukushima, that this will hopefully alleviate some of the fear that has been generated around this issue.” 


Associate Professor Nigel Marks is a Professor in Physics & Astronomy at Curtin University:

“In a couple of days, Japan will start releasing treated wastewater from the Fukushima nuclear power plant into the Pacific Ocean. The main problem with the release is that it sounds bad. But it actually isn’t. Similar releases have occurred around the world for six decades, and nothing bad has ever happened.

“The radioactivity in the Fukushima water is almost entirely tritium, a type of hydrogen. For scale, the Pacific Ocean contains 8,400 grams of pure tritium, while Japan will release 0.06 grams of tritium every year. The minuscule amount of extra radiation won’t make the tiniest jot of difference. A lifetime’s worth of seafood caught a few kilometres from the ocean outlet has the tritium radiation equivalent of one bite of a banana.

“Opponents of the release have suggested unrealistic alternatives and mustered a range of counterarguments, but none of these withstand scientific scrutiny. In truth, almost everything is radioactive, including the Pacific Ocean, where tritium accounts for a modest 0.04% of total radioactivity. Despite the controversy, ocean release is the only practical option at Fukushima, and every conceivable step has been taken to choose the best decision that considers all factors.”


Tony Irwin is an Honorary Associate Professor at the Australian National University. He is Technical Director of SMR Nuclear Technology Pty Ltd and Chair of Engineers Australia Sydney Division Nuclear Engineering Panel:

“There is an understandable perception that all radioactive materials are always and everywhere dangerous, particularly liquid waste, but not all radioactive materials are dangerous. The Fukushima water discharge will contain only harmless tritium and is not a unique event. Nuclear power plants worldwide have routinely discharged water containing tritium for over 60 years without harm to people or the environment, most at higher levels than the 22 TBq per year planned for Fukushima.

“For comparison the Kori nuclear plant in South Korea discharged 91 TBq in 2019, more than four times the planned Fukushima discharge and the French reprocessing plant at La Hague discharged 11,400 TBq in 2018 into the English Channel, more than twelve times the total contents of all the tanks at Fukushima, again without harm to people or the environment.

“It is important that the International Atomic Energy Agency (IAEA) has carried out an independent and transparent review of the procedures and equipment for discharges and its comprehensive report issued in July 2023 confirms that the release will have a negligible radiological effect on people and the environment. The IAEA will maintain a continuous on-site presence on site to independently monitor discharges.

“More tritium is created in the atmosphere than is produced by nuclear power reactors, and it then falls as rain. Ten times more tritium falls as rain on Japan every year than will be discharged. The discharge limit for release of radioactive water at Fukushima is 1/7th of the World Health Organisation standard for drinking water. The discharge is ultra-conservative.”



Declared interests

Paul Leonard advised that the Japanese authorities have sort appropriate advice from the International Atomic Agency that has been shared with radiological environmental scientists.

David Krofcheck: “No conflict of interest.”

Tom Scott: “I am a Royal Academy of Engineering funded Professor also part-funded by the UKAEA to develop the fusion fuel cycle. The fusion fuel cycle is all about tritium (one component of fusion fuel) and hence I do lots of research on tritium.”

Nigel Marks: “Nigel has not declared any conflicts of interest. He previously worked for Australian Nuclear Science & Technology Organisation (ANSTO) and received Funding from Australian Research Council, ANSTO & Los Alamos National Laboratory on radioactive waste storage materials..”

Tony Irwin: “Tony is technical director of SMR Nuclear Technology, an independent company that advises on the siting, development and operation of safe nuclear power generation technologies.”

For all other experts, no reply to our request for DOIs was received.

in this section

filter RoundUps by year

search by tag