CBC Interview about contaminated water releases from the Fukushima Daiichi Nuclear Power Plant

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Tuesday August 29, 2023 · 3:30 PM PDT

2023/08/29 · 15:30

A surfer wades into the ocean waves in Tofino, B.C. (Shutterstock / EB Adventure Photo) — A surfer wades into the ocean waves in Tofino, B.C. (Shutterstock / EB Adventure Phot0)

On Wednesday at 9:30 p.m. PT, Japan initiated the release of radioactive water from a nuclear power plant managed by Tokyo Electric Power Company (TEPCO), more than a decade after the facility sustained catastrophic damage.

On March 11, 2011, the Fukushima Daiichi plant was devastated by a massive magnitude 9.0 earthquake that triggered powerful tsunami waves, resulting in the meltdowns of three of its reactors. This incident stands as one of the most severe nuclear catastrophes in world history.

Having received approval from the Japanese government two years ago and after being given the green light by the UN's International Atomic Energy Agency last month, the discharge of radioactive water marks a critical phase in the decommissioning of the Fukushima Daiichi plant, a process that also involves the extraction of molten fuel destroyed by tsunamis, according to TEPCO.

The plant operator has indicated it will release the water in small quantities, with a number of safety checks in place. The initial release totalling 7,800 cubic metres (equivalent to about three Olympic-sized swimming pools), will occur over a span of approximately 17 days.

Passing of Joy Thompson (Joieau)

MarineChemist

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Monday January 09, 2023 · 11:00 AM PST

2023/01/09 · 11:00

Hello DK community. It has come to my attention that our community member Joy Thompson (Joieau) passed away in November 2022 following a heart attack. Joy worked as a radiation monitoring technician at the Three Mile Island nuclear power plant near Falmouth Pennsylvania following the meltdown there in 1979. Joieau was a very active member of our community and a staunch critic of the nuclear power industry and anti-nuclear weapons proliferation activist. While we did not see eye to eye on environmental radioactivity monitoring and risk assessment I valued her opinion and, although we never met in person, will miss her contributions to this community. There is a very well written retrospective about Joy and her partner Randall by environmental reporter Sue Sturgis that can be found here.

Condolences to her family and friends.

Radioactivity in fish and shellfish samples from the west coast of Canada after Fukushima (2011-18)

MarineChemist

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Monday June 13, 2022 · 10:20 AM PDT

2022/06/13 · 10:20

Map of fish samples collected from 2014 to 2018 through the InFORM project

The purpose of this post is to bring the public up to date on monitoring efforts of a research program into the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on environmental and public health here in North America. This post is part of an ongoing series summarizing work carried out by the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project which I led from 2014-2022. Radioactive contamination of the Pacific Ocean following the FDNPP accident raised public concern about seafood safety, particularly in coastal Indigenous communities in British Columbia where I live. To address this, InFORM along with Health Canada, Department of Fisheries and Oceans Canada and First Nations partners have collected and analyzed a total of 621 samples of commonly consumed salmon, ground fish, and shellfish from the Canadian west coast from 2011 to 2018. We examined the activities of cesium radioisotopes (¹³⁴Cs half-life ~2 years and ¹³⁷Cs half-life ~30 years) that were released in relatively large quantities from the Fukushima Dai-ichi Nuclear Power Plant (FDNNP) disaster in 2011 and would be most likely to pose radiological health concerns for human consumers of marine animals. Through careful analysis to determine the amount of radioactive isotopes in the seafood we have been able to carry out a health impact assessment. I wish to thank the following First Nations from British Columbia, Canada, for their generous donation of fish: Tr’ondëk Hwëch’in, Selkirk, Champagne and Aishihik, Taku River Tlingit, Tahltan, Nisga’a, Wet’suwet’en, Wuikinuxv, ‘Namgis, Hupacasath, Syilix, and Vuntut Gwich’in. I also thank Kayla Mohns and Brenna Collicutt of the Hakai Institute for assistance with the collection of shellfish samples. These results have recently been published in the peer-reviewed scientific literature in the Journal of Environmental Radioactivity and can be accessed here.

Highlights of the paper and key findings:

the vast majority of fish and shellfish did not have detectable levels of ¹³⁷Cs or ¹³⁴Cs where the minimum detectable level was 0.7 — 1.0 Bq kg^-1 fresh weight for 6 hours of analysis by counting with a sensitive gamma emission spectrometer
19 fish that had detectable levels of ¹³⁷Cs were freeze dried and recounted for 336 hours and found to have an average ¹³⁷Cs content of 0.29±0.02 Bq kg^-1 fw
2 of these 19 fish had detectable levels of ¹³⁴Cs, the short-lived isotope, which showed clearly that fallout from the FDNPP was present in these particular fish. Given that the ratio of ¹³⁷Cs:¹³⁴Cs in the releases from the FDNPP was 1:1 we determined that the contribution of contamination in these fish from the nuclear accident was 49% and 24% respectively with the majority of caesium contamination coming from other sources like nuclear weapons testing and the Chernobyl disaster in the 20^thcentury
38 shellfish showed no contamination from FDNPP in either their shells or meat
8 years of measurements showed that radioactivity in fish was dominated by naturally occurring radioisotopes and that levels of human-made radioisotopes remained small in the Pacific off North American following the FDNPP disaster
upper bounds for ingested doses of ionizing radiation from ¹³⁷Cs was determined to be ~0.26 micro-Sieverts per year and far below the annual effective dose of 2400 micro-Sieverts from exposure to other sources of radiation
we conclude that fish and shellfish from the Canadian west coast are not a radiological health concern despite the FDNPP accident of 2011

MarineChemist

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Monday March 01, 2021 · 4:51 PM PST

2021/03/01 · 16:51

The purpose of this post is to draw attention to an upcoming event marking 10 years since the Fukushima Daiichi Nuclear Power Plant (FDNPP) meltdowns and presenting the results of research into how the disaster has affected ocean health. This post is part of an ongoing series dedicated to reporting on scientific research into the environmental and public health implications of the FDNPP meltdowns.

One of the largest recorded earthquakes in history and a remarkable tsunami on March 11, 2011 lead to the initial and ongoing releases of radioactive materials from the FDNPP.

On March 4th the research community will look back at what we’ve learned over the past 10 years during two virtual panels, both at 7:30 pm, one timed for Tokyo with the second for the U.S. East Coast, using simultaneous translation at the Tokyo event for Japanese and English speakers.

I encourage anyone interested here to register for these free panel events at the following link.

https://cmer.whoi.edu/10-years-of-study-and-insight/

The panels will be moderated by PBS science correspondent Miles O’Brien, with keynote introductions by Atsuko Toko Fish (Tokyo event) and Caroline Kennedy (US event). The panel of four experts- J. Kanda (Tokyo U. Marine Sci & Tech), K. Buesseler (WHOI, USA), S. Charmasson (IRSN, France), A. Brown (Safecast, Japan)- will review events that occurred, explore the fate of the radioactive contaminants in the ocean, the consequences for marine life and human consumers of seafood, and finally explore communication of these events to the public. The presentations and panel discussion will be moderated with the general public in mind and will be of interest to policy-makers, industry leaders, and the research community. It will also include time for questions from the audience.

Finally, during the week of March 4-11, we will host a virtual poster session accompanied by short audio presentations in English and Japanese with the option to leave your questions for the poster authors.

Together, the keynotes, panels, and poster session will offer a fitting memorial of events in 2011 and will also provide an informative and accessible summation of work that occurred over the past decade as a result.

I highly encourage those of you with interest in how the FDNPP meltdowns affected public and environmental health to attend.

MarineChemist

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Monday March 11, 2019 · 5:00 AM PDT

2019/03/11 · 05:00

no image description available — Summary infographic for the Fukushima InFORM project including our measurements in North America, Japanese measurements, historical data and safety guidelines.

I am writing this post is to bring the public up to date on monitoring efforts of my research program into the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on environmental and public health here in North America. This post is part of an ongoing series summarizing work carried out by the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project. Eight years since the peak in releases to the environment our project continues to measure radioisotopes released from the FDNPP that have the potential to present radiological health risks to living things. InFORM makes measurements of levels in seawater and common marine organisms as consumption of seafood is one of the most likely ways that residents of North America could be exposed to Fukushima derived contamination. We have found that:

Maximum contamination levels in seawater from Fukushima measured in waters offshore (~1500 km) and onshore British Columbia are now known to be about 8 to 10-fold lower than levels present in the North Pacific during the height of atmospheric nuclear weapons testing in the 1950’s and 1960’s. These levels are roughly 1000-fold below the maximum allowable drinking water standards for these isotopes.
Levels in Pacific salmon returning to North America have not changed in a statistically significant way since before the disaster and are lower than peak levels measured in the 1960’s.
As was reported in 2015 in this comprehensive study by Health Canada and backed up by measurements made by the international scientific community the release of radioisotopes from Fukushima will have no measurable impact on the health of the marine ecosystem in the northeast Pacific nor on public health in North America.

Eight years after this disaster it is important to remember those lost in the tsunami and those still displaced from their homes and communities struggling to recover.

MarineChemist

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Thursday December 06, 2018 · 11:34 AM PST

2018/12/06 · 11:34

Earl Marriott Secondary School sampling for InFORM at Bamfield Nov. 2018 — Students from Earl Marriott Secondary School collecting the Nov. 2018 seawater sample for InFORM at Bamfield Marine Science Centre, Bamfield, British Columbia, Canada.

The purpose of this post is to provide readers with a brief update on our citizen science sampling program that is monitoring seawater concentrations of contamination derived from Fukushima Daiichi Nuclear Power Plant (FDNPP) meltdowns. This post is part of an ongoing effort to provide scientifically sound information regarding the environmental and public health impact of the disaster and to combat misinformation commonly found online. Coastal sampling is carried out by our volunteers at 16 locations up and down the coast of British Columbia to complement offshore sampling in the north Pacific and Arctic Oceans by scientists working from research vessels. Results of samples collected up until May 2018 indicate the following:

Levels inshore continue to increase as the bulk of contamination released from FDNPP in March-April 2011 arrive at the coast
Seawater contamination levels are ~8-10-fold lower than those measured here at the height of atmospheric nuclear weapons testing between 1958-1963 last century
Levels measured now do not approach levels known to represent a significant health risk to marine organisms or human beings
Given that release rates of radiologically significant isotopes from the FDNPP site are very small compared to rates at the height of the disaster in March-April 2011, levels of contamination and risk are unlikely to increase in the future

Since 2014 the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project has been monitoring levels of radioactive contamination in seawater and marine organisms to conduct a thorough assessment of the risk presented by the FDNPP disaster for the marine and public health in Canada. An important part of this project is the work of citizen scientist volunteers that collect seawater (20 liters or ~5 gallons) for us each month at various locations along the British Columbia coast and send it back to our labs for analysis. You can read about how these samples are collected and analyzed here. Samples are analyzed for Cesium-137 (¹³⁷Cs, half-life ~30 years), and Cesium-134 (¹³⁴Cs, half-life ~2 years). These isotopes are useful because they are relatively easy to measure, were released in relatively large quantities from the FDNPP, and because the short half life of ¹³⁴Cs serves as a fingerprint of the disaster as all other human sources of this artificial isotope have decayed away from the environment.

LaxKw'alaams_Dec2017.jpg — Students of the Coastal Tsimshian Academy collecting seawater for InFORM in Dec. 2017.

Locations where samples are collected are indicated on the map below:

Coastal monitoring stations where citizen scientists sample seawater each month for the InFORM project.

The following figures summarize our most recent results and compare the concentration of ¹³⁷Cs in coastal versus offshore seawater over the last number of years.

Concentration of 137-Cs (Bq m^-3) in seawater collected at all coastal stations from Oct. 2014 to May 2018. Grey solid line indicates the monthly average of all stations, dashed white line indicates a linear increase and dashed black line indicates the maximum levels of contamination measured offshore (~1500 kilometers) in the northeast Pacific. The 10,000 Bq m^-3 Health Canada action level for drinking water is shown in red.

Contamination levels continue to show a significant amount of regional variability where communities on the west coast of Vancouver Island and on Haida Gwaii in the North with more exposure to the open ocean having relatively higher ¹³⁷Cs levels compared with communities nearer the mainland in the Salish Sea. This is consistent with the contaminated water arriving in the northeast Pacific due to transport by the North Pacific Current and spreading toward the coast. The general trend along the coast is that ¹³⁷Cs is increasing over time which is to be expected as the plume of contaminated water arrives. On the right panel above you can see that while offshore contamination levels have stabilized and started to drop the coastal waters are increasing toward the maximum values seen offshore. These levels (<10 Bq cubic meter of seawater) offshore and at the coast are so low as to be an insignificant threat to the health of marine organisms or human beings who rely on the ocean for food and recreation. Indeed, this contamination is so small relative to the ionizing radiation emitted by naturally occurring isotopes that are always present in seawater, that without incredibly sensitive equipment these levels are not measurable (e.g. with a geiger counter). Given that levels offshore have reached a peak that is well below levels known to cause harm to living things we do not expect any measurable risk along the coast of British Columbia in the future.

The InFORM program is funded to continue our monitoring efforts into 2019 and I will continue to report these results as they become available.

Megan Ives of Sandspit, Haida Gwaii collecting the November 2018 sample for InFORM.

Update: Fukushima Derived Contamination in Pacific Surface Water Up Until 2017

MarineChemist

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Friday October 26, 2018 · 4:27 PM PDT

2018/10/26 · 16:27

Northeast subarctic Pacific from the deck of the Canadian Coast Guard Ship J.P. Tully in September 2018

The purpose of this post is to summarize a recently published, peer-reviewed study that documents levels of Fukushima derived contamination in surface waters of the Pacific Ocean. This post is part of an ongoing series aimed at communicating scientifically derived information about the impact of the disaster on marine environmental and public health. Michio Aoyama and colleagues measured the activity of Cesium-137 (¹³⁷Cs, half life ~30 years) and Cesium-134 (¹³⁴Cs, half life ~ 2 years) in seawater collected from the western Pacific Ocean including waters off the coast of Fukushima Prefecture from 2011-2017. They found the following:

Contamination decreased dramatically and rapidly in waters offshore of the Fukushima Daiichi Nuclear Power Plant (FDNPP) from maximum values of ~3000 Becquerel per cubic meter (Bq m^-3) of seawater in 2011 to values in 2015-16 of ~2-3 Bq m^-3. This precipitous decline is consistent with the ongoing but relatively low rates of release of radionuclides from the site compared to the bulk of contamination that was released in March-April 2011.
Levels of ¹³⁷Cs close to FDNPP now are similar to levels of contamination present there before the disaster occurred (1.5-2 Bq m^-3) owing to atmospheric nuclear weapons testing in the middle of the 20^th century.
Levels in the western Pacific were around 1-7 Bq m^-3 in 2011-2012 but stabilized at lower values in 2017.

Levels being measured in nearshore and offshore waters in the western Pacific near to Japan do not approach levels known to represent a credible risk for ocean or public health. These results in the western Pacific are consistent with what the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project is finding in the eastern Pacific off of North America.

Aoyama and others recently published their study in the Journal of Environmental Radioactivity. The collected and analyzed surface seawater for the presence of radiocesium isotopes between 2011 and 2017 in waters of the western Pacific in the following locations:

Boundaries of areas (boxes) sampled by Aoyama et al. (2018) in the western and central Pacific Ocean.

The activity of ¹³⁷Cs and ¹³⁴Cs in Bq m^-3 with time that they found are summarized in the following figure:

1-s2.0-S0265931X17307750-gr2_lrg.jpg — Long term trends (2011-2017) in radiocesium activity in boxes defined in the first figure. Solid blue squares are ¹³⁷Cs activity concentration and open red circles represent ¹³⁴Cs.

The researchers found that in Box 2 (closest to the FDNPP) contamination in surface waters offshore were highest in early 2011 coincident with the largest releases from the site in March-April of that year when the vast majority of radionuclides were released to the atmosphere and directly to the ocean. Values dropped dramatically so that by 2014-2016 levels were ~3 Bq m^-3 and similar to levels of contamination measured before the disaster occurred owing to nuclear weapons testing that occurred in the 1950s-60s. Note that the concentrations of ¹³⁴Cs diminish relative to ¹³⁷Cs, and the red symbols on the figure diverge from the blue symbols, because ¹³⁴Cs has an ~2 year half life and is decaying away from the environment much more rapidly. Indeed, it is becoming increasingly challenging analytically to detect Fukushima ¹³⁴Cs in environmental samples. Contamination farther offshore in Boxes 4-6 indicate that maximum levels of contamination from Fukushima approached by did not exceed 200 Bq m^-3 in 2011 and are now ~2-3 Bq m^-3.

Based on best estimates of how much radiocesium was released from FDNPP in March-April 2011 the authors used a model of the water circulation and mixing in the Pacific to predict the levels and movement of Fukushima ¹³⁴Csin the Pacific from April 2012 until October 2016. The results of the modeling study are summarized in the following figure:

1-s2.0-S0265931X17307750-gr3b_lrg.jpg — Horizontal distribution of ¹³⁴Cs from Fukushima for the period April 2012 to October 2016. Open circles represent observations/measurements of ¹³⁴Cs while shading reflects model results.

What the model and observations indicate is that the bulk of contamination from the site went into the Pacific Ocean in 2011 and that rates of release from the site after that time are very small in comparison. Most of the Fukushima contamination is now in the eastern Pacific near to North America and that levels in behind the main body of contamination are difficult to detect. Similarly, the lack of appreciable ¹³⁴Csand ¹³⁴Cs/¹³⁷Cs activity ratios close to FDNPP indicate that there is little evidence for ongoing fission in the reactors at the site as is commonly speculated by those with little scientific training. The levels the scientific community is measuring close to FDNPP and those expected and measured in waters close to North America do not represent a significant risk to the marine ecosystem or public health.

The Fukushima InFORM project will continue its monitoring activities in the eastern Pacific until Spring 2019.

Monitoring Fukushima Contamination in Pacific Salmon and Soil in British Columbia

MarineChemist

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Sunday March 11, 2018 · 3:54 PM PDT

2018/03/11 · 15:54

Sockeye salmon, Oncorhynchus nerka, also called red salmon, showing the distorted jawline that occurs prior to spawning. — Sockeye Salmon as photographed by Eiko Jones in Campbell River British Columbia

Seven years on, since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, it is useful to start to bring together information from scientific studies of the impact of the contamination on the North American environment and its people. I recently wrote to communicate the most recent results of the Integrated Fukushima Ocean Radionuclide (InFORM) project. This post summarizes a recently published, peer-reviewed paper by colleagues lead by Dr. Krzyzstof Starosta of Simon Fraser University in BC working in parallel to InFORM. The open access paper was published in the Canadian Journal of Chemistry and was recently recognized with the “Best Paper Award” by the journal. They studied the concentrations of anthropogenic radioisotopes (¹³⁴Cs half-life ~2 years, ¹³⁷Cs half-life ~30 years) and naturally occurring radioisotope ⁴⁰K (half-life 1.25 billion years) in Pacific salmon (sockeye, chum and chinook) and in soil and roof debris collected in southern British Columbia to determine the local impact of the FDNPP accident. Their results were as follows:

¹³⁴Cs (a fingerprint of Fukushima contamination) was not detected in any of the salmon samples
¹³⁷Cs was not detected in sockeye or chum salmon but was detected in all chinook with an average level of ~0.2 Bq kg^-1
annual dose from artificial radionuclides to a human consumer of chinook salmon was estimated to be ~1/300 of the dose owing to naturally occurring isotopes in the fish and ~1/30,000 of the annual dose experienced for all other natural sources by the average Canadian
Most soil samples contained ¹³⁴Cs and ¹³⁷Cs which was delivered to the region by atmospheric transport shortly after the disaster
Levels of Fukushima radioisotopes in soil did not approach levels known to be harmful to living organisms

Consistent with other monitoring in the area the results of the study indicate that given the trace levels of contamination present the impact of the FDNPP accident on ecosystem and public health in North America will be insignificant.

MarineChemist

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Thursday March 08, 2018 · 8:42 PM PST

2018/03/08 · 20:42

aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzA1NS83MzYvb3JpZ2luYWwvZnVrdXNoaW1hLWRhaWljaGktbnVjbGVhci1wbGFudC5qcGc_.jpeg — The Fukushima Daiichi Nuclear Power Plant (FDNPP) and surroundings before the tragic events of March 11, 2011

The purpose of this post is to bring the community up to date on monitoring efforts aimed at understanding the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on environmental and public health. This post is part of an ongoing series and will focus on North American monitoring, summarizing work carried out by the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project. Seven years since the peak in releases to the environment our project continues to measure environmental levels of radioisotopes that could represent a radiological health risk to living things. InFORM makes measurements of levels in seawater and common marine organisms as consumption of seafood is one of the most likely ways that residents of North America could be exposed to Fukushima derived contamination. Maximum contamination levels in seawater from Fukushima measured in waters offshore and onshore British Columbia and in the Arctic Ocean are about 8 to 10-fold lower than levels present in the North Pacific during the height of atmospheric nuclear weapons testing in the 1950’s and 1960’s. These levels are roughly 1000-fold below the maximum allowable drinking water standards for these isotopes. Levels in marine organisms have not changed significantly since before the disaster. As was reported in 2015 in this comprehensive study by Health Canada and backed up by measurements made by the international scientific community the release of radioisotopes from Fukushima will have no measurable impact on the health of the marine ecosystem in the northeast Pacific nor on public health in North America.

MarineChemist

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Monday December 18, 2017 · 11:41 AM PST

2017/12/18 · 11:41

This post is based on a more detailed post by Dr. Jonathan Kellogg on the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project website. It contributes to an ongoing effort to provide scientifically derived evidence to determine Fukushima’s impact on environmental and public health. After extended testing of select 2016 salmon samples the Fukushima-fingerprint isotope was found in single fish. The maximum level of contamination observed in this sample (¹³⁴Cs, 0.07 Bq kg^-1; ¹³⁷Cs, 0.51 Bq kg^-1) is over 1,700 times lower than the Health Canada Action Level (1,000 Bq kg^-1) and does not represent a significant health risk for either the fish in question or consumers of Pacific salmon including human beings. The InFORM project continues its monitoring of seawater and marine biota for signs of Fukushima derived contamination to assess the potential impact on the marine ecosystem and public health. Results are reported as they are generated here.

MarineChemist

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Tuesday September 26, 2017 · 5:01 PM PDT

2017/09/26 · 17:01

This undated picture released by North Korea's official Korean Central News Agency (KCNA) on September 3, 2017 shows North Korean leader Kim Jong-Un (C) looking at a metal casing with two bulges at an undisclosed location..North Korea has developed a hydrogen bomb which can be loaded into the country's new intercontinental ballistic missile, the official Korean Central News Agency claimed on September 3. Questions remain over whether nuclear-armed Pyongyang has successfully miniaturised its weapons, and whether it has a working H-bomb, but KCNA said that leader Kim Jong-Un had inspected such a device at the Nuclear Weapons Institute. / AFP PHOTO / KCNA VIA KNS / STR / South Korea OUT / REPUBLIC OF KOREA OUT ---EDITORS NOTE--- RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO/KCNA VIA KNS" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS.THIS PICTURE WAS MADE AVAILABLE BY A THIRD PARTY. AFP CAN NOT INDEPENDENTLY VERIFY THE AUTHENTICITY, LOCATION, DATE AND CONTENT OF THIS IMAGE. THIS PHOTO IS DISTRIBUTED EXACTLY AS RECEIVED BY AFP. / (Photo credit should read STR/AFP/Getty Images) — If North Korea possesses a thermonuclear device and detonates it in the low atmosphere how much radioactive fallout can we expect?

The purpose of this post is to conduct a thought experiment to arrive at (I hope) a useful estimate of how much radioactive contamination might occur if North Korea detonates a thermonuclear weapon in the lower atmosphere over the North Pacific Ocean. There are a significant number of unknowns, not the least of which is the fundamental uncertainty as to whether the rogue nation has successfully tested a Teller-Ulam style thermonuclear weapon or not. I explain my assumptions and compare the resulting global release of radioisotopes that represent a radiological health concern from such a test to the amounts recently released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) disaster, the Chernobyl disaster and aggregate atmospheric weapons testing in the last century. I invite comments and an accounting of the approach used here and how it might be improved. The estimates represent a worst case scenario I think as there are serious questions as to whether the North Koreans possess thermonuclear weapons similar to those tested by other countries in the past and whether or not they could deliver a weapon similar in yield to their most recent underground test to the atmosphere. I find that a North Korean test over the Pacific would likely release:

similar amounts of ⁹⁰Sr but much lower ¹³⁷Cs as the Fukushima Daiichi nuclear disaster to the environment
more ¹³¹I than Fukushima but 2-3 fold less than Chernobyl
release up to 2000-fold more Pu globally than did Fukushima but 10-100 fold less than Chernobyl

The health consequences of these releases are beyond the scope of this post but would depend on (among other things) the height that the weapon was detonated in the atmosphere, the location of the detonation over the Pacific and atmospheric circulation that would all dictate where the isotopes would be deposited. The deposition distribution would determine the dose experienced by living organisms through external and internal pathways.

MarineChemist

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Wednesday September 06, 2017 · 11:26 AM PDT

2017/09/06 · 11:26

Proposed migration routes of Pacific marine-life from the western to eastern part of the ocean basin.

The purpose of this post is to report on a recently published, peer-reviewed study that investigated the levels of Fukushima derived contamination in migratory Pacific predators. The post is part of an ongoing effort to inform interested members of the public what the scientific community is finding about the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) disaster on environmental and human health. Madigan and colleagues looked for radiocesium (¹³⁴Cs, half life ~ 2 years; ¹³⁷Cs, half life ~30 years) in a variety of large, predatory organisms in the North Pacific Ocean between 2012 and 2015. Their results were as follows:

Fukushima derived ¹³⁴Cs could not be detected in any of the organisms with the exception of a single olive ridley sea turtle with trace levels (0.1 Bq kg^-1 dry weight)
Levels of ¹³⁷Cs varied in the organisms but were generally unchanged compared with levels measured in organisms prior to the FDNPP disaster (pre-2011)
Levels of ¹³⁷Cs were roughly 10 to 100-fold lower in the organisms than levels of naturally occurring Potassium-40 (⁴⁰K)
Neither the levels of radiocesium or ⁴⁰K approach levels known to represent a significant health risk to the animal or human consumers

These direct measurements of contamination levels in marine predators suggest that assuming that Pacific organisms will accumulate detectable FDNPP contamination is unwise. Similarly, anxiety and speculation about the dangers of radiocesium bioaccumulation in the face of such data seems unfounded.

Between 2012 and 2015 a total of 91 different organisms from a variety of predatory marine groups were sampled and analyzed for the presence of radiocesium contamination and naturally occurring⁴⁰K. The human made isotope ¹³⁴Cs, with its relatively short ~2 year half life, serves as a fingerprint of FDNPP contamination as all other human sources are sufficiently distant in the past to have completely decayed away in the environment. Organisms sampled and their radioisotope content are reported in the following table:

With the exception of a single olive ridley sea turtle no detectable (<0.1 Bq kg^-1 dry weight) trace of FDNPP ¹³⁴Cs contamination was found. Levels of ¹³⁷Cs found in the organisms were similar to levels measured pre-Fukushima. In addition, the ¹³⁷Cs levels were less than 0.2% of US FDA levels of concern (370 Bq kg^-1 wet weight) and less than 0.05% of US FDA derived intervention levels (1200 Bq kg^-1 wet weight). Simply stated levels in these organisms would have to be >1600-fold higher to be designated unfit for market. The levels and ionizing radiation dose to consumers from naturally occurring ⁴⁰K dwarfed those from FDNPP radiocesium. Radiocesium derived ionizing radiation doses were <1% of those from ⁴⁰K. Neither the doses from ⁴⁰K or cesium isotopes approached, even remotely, those known to affect the health of the organisms or consumers of these organisms.

These results are consistent with those of the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project which is assessing the impact of the FDNPP disaster on the health of Canadian marine systems and public. Ongoing, scientifically rigorous, monitoring of the marine environment provides the best evidence with which to gauge the risk that the FDNPP meltdowns represent for marine and public health here in North America.

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CBC Interview about contaminated water releases from the Fukushima Daiichi Nuclear Power Plant

Passing of Joy Thompson (Joieau)

Radioactivity in fish and shellfish samples from the west coast of Canada after Fukushima (2011-18)

Fukushima 10 Years On: Free, public, virtual conference on scientific research into ocean impacts

Insignificant Environmental and Public Health Risk from Fukushima in North America 8 Years On

Update: Citizen Scientists' Continued Efforts to Monitor Fukushima Derived Contamination in Canada

Update: Fukushima Derived Contamination in Pacific Surface Water Up Until 2017

Monitoring Fukushima Contamination in Pacific Salmon and Soil in British Columbia

Update on Fukushima Monitoring Activities in North America: 7 Years On

Extraordinary Measures: Solitary Pacific Salmon Found With Detectable Fukushima Contamination (2016)

North Korean Atmospheric Thermonuclear Test: How much contamination can we expect?

How much Fukushima contamination is there in migratory Pacific fish?