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Sampling sea and riverbeds around Fukushima Nuclear Power plant

We have put together a valuable set of sediment samples from riverbeds, estuaries and seabed nearshore in the Tohoku region of Japan, mostly in the vicinity of the Fuksuhima Daiichi Nuclear power plant. Half of the samples have been taken before the Typhoon VongFong, the other half during the Typhoon VongFong (Oct 13th 2014 over Tohoku region).  The goal is to understand the motion of sediments from land to sea using radioactive tracers, in other words “make a map of seabed radioactivity around the Fukushima Power Plant“. Here a rough analog simulation – and here an excellent scientific paper explaining how radioactivity “travels” seasonally that we try to extend – connecting land / river to sea data. We do not have the results / measurements of Cesium of our samples yet, hopefully before the end of 2014.

Video by Philippe Couture

The instrument we use is a “Micro Rolling Trawler” that we developed that captures only a few millimeters of surface (recent) sediments. That allows us to have a “snapshot” of the seabed surface.

Sampling river and sea bed sediment with radioactive tracers from Fukushima Mapping Radioactivity in riverbeds and seabeds around Fukushima power plant Crippled Fukushima Nuclear Power Plant 20141009 Sediments Samples
Photos by Julie Nagai

All the data we collect is publicly available for free. We will study mostly Cesium. If you are interested in these samples to analyse other isotopes, we would be very happy to share with you free of charge as long as you share publicly the data / results. Please get in touch :

Many thanks to Julie Nagai, Philippe Couture, Jun Kamei, Shinya & Angela Saeki, Dr Olivier Evrard, Kenichi Kawamura, Prof Hiroshi Kainuma, Umilabo, Soness Stevens, Rohini Karen Deblaise, Dean Newcombe, Safecast Joe Moross, Prof Yoshida of Tohoku University, Christina Moorehead, Jay Klaphake, Kaori Hilton, Maria Ichizawa, Takuro Mizuta, Hiroshi Nomura, Katagiri Family, Zhiruo Gao, Yoshiko Toyama, Toby Marshall and all those who supported our efforts. You can see where we drove with Safecast bGeigieNano (Oct 7, Oct 8, Oct 13, Oct 14)  or as one big map.

More soon…

In Japan to map seabed radioactivity around Fukushima crippled power plant

Mapping Seabed Radioactivity together Participative, low cost, open source radioactivity mapping of Tohoku coast




Please download pdf here :

This is why we are in Japan. Please help us find a boat and map seabed radioactivity.

Please support us by voting for us here :


Text in English : 

The problem

The Fukushima nuclear power plant is leaking into the ocean, directly from the power plant, but also down the mountains via the rivers. We have great independent radiation maps on land by Safecast (JP), good sediment transports (rivers) maps by the CNRS (FR), and good simulation of ocean currents by NOAA (USA). A very important missing piece of the puzzle is a comprehensive map of seabed radioactivity. If we want the fisheries to re-open and swim safely in these waters, this information is crucial for everyone. 

Our idea

How to measure radioactivity on the seabed? Currently there are a few points being measured in strategic areas with Eckman bottom grab samplers. They are great machines but

  • mix surface sediment (more radioactive) and deeper sediment (less radioactive)
  • they let very thin particles sip out the jaws
  • they are quite expensive and bulky

We’re developing a rolling surface sediment sampler. A very low cost machine that you can operate at the end of a fishing rod from any boat that only captures a few millimetres of sediment surface (most recent and most radioactive). The bigger picture is to gather data and produce a map similar to Safecast on land, but for the seabed, by everyone for everyone.

How you can help

We are looking for a boat to test our idea.

Any boat. If you have a boat or know someone who can take us there, please let us know.We would love to sail along Japan east coast, for example from Iwaki to Sendai, in the legal waters of course.

The samples we collect would be time, depths and geo coded (with GPS) and made available to anyone who want to analyse and share publicly the results. We are working with SAFECAST and the French CNRS, extending their work in riverbeds into the ocean using their methods and instruments.

Dates : 2014/10/02 -10 and 2014/10/12 – 17
Money : we pay fuel, water, food so it is free for you.

Data : Public Domain

Please contact :

Cesar HARADA. French-Japanese Ocean roboticist, Former MIT Project leader, TED Senior Fellow.
Philippe COUTURE. French documentary Film maker, architect & permaculture researcher.



Text in Japanese  :

協働型 海底放射線マッピング







- 表層部分(放射性が強い部分)と深い部分(放射性が弱い)が混ざる

- 細かい物質を取りこぼす

- 高価格、かさばり運搬に不適用

わたしたちは、転動式海底表面堆積物試料採取器(rolling surface sediment sampler)を開発しています。非常に安価な機械で、どんなボートからでも、釣竿の先に取り付けて操作でき、数ミリの海底の表面の堆積物(もっとも新しく、もっとも放射性が高い)部分を測定します。最終的な目的は、誰もが自分でデータを収集し、誰でも見ることのできる、陸地の Safecast に準ずる海底のマップ作成です。






調査日時:2014年10月2日から10日、および  2014年10月12日から17日


データ:公有財産(Public Domain)


Cesar HARADA (メール 海洋ロボティックを専門とする日系フランス人。MITプロジェクトリーダーの経歴を持つTEDシニアフェロー。

Philippe COUTURE (メール: )フランス人ドキュメンタリー映画作家、建築家、パーマカルチャー研究者。


Environmental Radioactivity, an audiovisual Introduction

"Green groups fear 'most dangerous' nuclear power plant on Hong Kong's doorstep" South China Morning Post


I now teach kids at the Hong Kong Harbour School. It is the first time I have taken a long term commitment (2 years) to teach classes to the young, before I was only teaching at master level in Europe. It’s not a smaller challenge. I have to teach differently. I have to explain things from scratch with non-technical words. I have to be super articulate and clear. And more importantly it’s got to be directly relevant to them, meaningful and rewarding at every step.

They will ask questions that will keep me awake at night. They deserve answers, but more importantly, they need to develop the capacity to inquire and propose their own answers, have their own opinions and strategies to affect change to society.

Radioactivity in Hong, Safecast Map, Mac App
Map by Safecast showing radioactivity in Hong Kong with the brand new Mac (free) app. Government data here.

The topic of environmental radioactivity is timely :

For the first class, I have prepared a slideshow with many videos. I have watched many crazy and inadequate videos and these are the most informative ones. More about environmental and marine radioactivity coming soon.

Share or watch in full screen :

20130330 Cape Town, South Africa

Cape Town is a spectacular city. The mountains that surround the city. The beauty of the ocean. The powerful winds. Captured above by our wonderful media team having lots of fun at work.

Before I die, I want to ..., Cape Town, South Africa
First thing we did in Cape Town was to go and meet with Gabriella’s friend who owns a fashion shop called Unknown Union in the hip area of the city. At the entrance of the shop, we were so surprised to find the installation of a my friend Candy ChangBefore I die, I want to …” !

Every time I come across Candy’s work, it reminds me of the good times I had when I was living in New Orleans a few years back, living in the same street as Candy in the Bywater. It reminds me of my dreams, it reminds me that everyone has amazing dreams, and we’re all in this world to make them all happen…

The SAP pitch event

Protei in Cape Town, South Africa

cape town, south africa

The pitch event went very well, additionally to our “classic” pitch we added a soundtrack that was emotional and I think it really worked !I love the idea of making a music hall instead of a pitch event :) We won the SAP pitch event in Cape Town and the reward was …

A diner in a chic restaurant with all mentors and special guests

Protei wins SAP Pitch in Cape Town and diner with Unreasonable at Sea Mentors

From left to right, Kamran Elahian, Chris Shipley, Gabriella LevineRozan Ahmed, Daniel Epstein, Prince Fahad Al Saud, Cesar Harada, Matt Mullenweg, Mimi.

We were very fortunate to share the table with this group of exceptional people. Many of which were our influential mentors.

Koeberg, Africa only nuclear power plant

cape town, south africa

We spent about 2 days investigating about Koeberg, Africa one and only nuclear power plant. We rented a car, drove there twice.

Protei in Koeberg, South Africa

You may be positively surprised to hear that the levels of radioactivity that we measured around the nuclear power plant were acceptable. In fact we had higher levels in the center of Cape Town than close to the Koeberg plant. We measured levels on the beach, and in the water at about 1 meter underwater with the sensor we customised with Safecast for the Fukushima expedition. We were able to pay a little visit at the Koeberg Visitor Center and learn all about the plant and the technology they use. Many kids were also visiting. We were not allowed to approach the power plant closer than 2 kilometers. According to documentation in the plant, the cooling of the reactor causes the temperature of the sea to be significantly increased (up to 10ºC) outside the plant outake of water. It was surprising to see that the Nuclear power plant is installed in the middle of a natural reserve that is a highly secured perimeter. What it felt was that the natural reserve was more of an excuse to keep curious people and activist at a greater distance… I’m now curious about the radioactivity levels at Vaalputs in the Northern Cape where the used fuel is disposed.

The local makers

Protei in Cape Town, South Africa

Thanks to our connexion Ralph Borland that we knew from the Science Gallery back in Dublin, we were able to have a really nice insight into the maker / designer culture of Cape Town.

Protei in Cape Town, South Africa

We were introduced by Paul Mesarcik to the local designer / maker’s world.
Below Protei INC Art Collection very first acquisition !!! Who is the artist?

Protei in Cape Town, South Africa

The Cape Town University

OPENROV cape town, south africa

We were delighted to find a customised version of OpenROV at the University of Cape Town. Protei and OpenROV have shared a wonderful time at TechShop SF Summer 2012, it is super encouraging to see OpenROV in other countries, being modified and used.

Protei in South Africa

Thanks to Paul Mesarcik that studied electro-mechanics at Cape Town University, we were introduced to Dr Robyn Verrinder of the Research and Instrumentation, Departement of Electric Engineering of Cape Town University. We discussed with local researchers their their latest development in autonomous sailing robot. Above, a freshly build hull that is being compartmentalised and ballasted with fishing lead weights in the bulb. Quite a few researchers are now interested in developing autonomous sailing robots, this is the people we want to involve with Protei!

The Gangster Incubator

Protei in South Africa

We were lucky to meet Marlon Parker (Facebook) of Rlabs who introduced us to many inspiring young people in a not very inspiring neighbourhood. They explained us about their community, the hope they found, how the access to technology helped them feel empowered to look a their future, how it re-enchanted their lives.

We want to keep in touch with the RLabs.

Shuttleworth Foundation

We were lucky to meet with some people at the Shuttleworth foundation. Thumbs up for the Foundation!

Marine Transect, Moving Sushi

The stereo imaging system in action underwater
They explained us how they  sample the coral reef ecosystem using stereo-video to determine fish density, biomass, diversity and community structure along 1 500 km of the Western Australian coastline.

We were kindly introduce by Bernelle Verster of TEDxCapeTown to the amazing crew of MarineTransect & Moving Sushi Michael and Linda Markovina, Justin Beswick .

They just arrived from a 4 months journey the day before our departure from Cape Town! We had to meet!

The East African Marine Transect expedition is a not-for profit expedition that is managed and facilitated by Moving Sushi. Moving Sushi actions strong ideas by facilitating globally important marine-based scientific expeditions to explore the relationship between humanity, our marine environment, science, technology and how new knowledge is communicated and shared through open source channels.

They just completed  234 dives, were quite tired, and after sharing a quick breakfast they went back to unpack their boat.

Joe Heywood of North Sails

Our last encounter in South Africa was with Joe Heywood of North Sails. It was great sitting down with his family, sharing food and geeking about sail / rig designs. Thanks a lot for your precious advices Joe!

20130218 Vietnam, Croire ou Douter?

Saigon's friends

First thing we did in Saigon (Ho Chi Minh City, Vietnam) was to meet with my old friend Truc-Anh and his girlfriend Penelope Cadeau in a typical street cafe. Meeting with familiar people in a new city makes a new city familiar. From left to right: hand of Olimpia Meija Corliss, Matt Corliss, Truc Anh, Penelope Cadeau. I’ve known Truc-Anh for 10 years, we were together in school at the Ecole Boulle in Paris before he moved to study circus, dance, painting and now he’s doing more and more photography. Penelope is doing delicate fashion accessory under the label “La fiancée du facteur”, modelling and many other things creative. Truc-Anh is of Vietnamese origins, but it is Penelope that convinced him to come back to this booming city.

“Croire, Douter” – “Believe, Doubt” – what he calls a “GAME OF FAITH”, that may be playing with your own mind like playing with fire, an installation that was part of an impressive personal exhibition in Vietnam’s best art gallery, Galerie Quynh.
Truc Anh recommended us a scooter rental for a week with an acquaintance of him and off we went.

Natural Artificial, Artificial Natural

We enjoyed a lot scooting around Vietnam, Saigon has the highest density of motorised 2 wheelers in the world. People were kind given they were not in a hurry. Most young people spoke english, really old people spoke french and were very engaging. For Protei, we explored 2 sites in particular :

  1. One pond that used to be natural natural and sane, in the middle of the city and is getting “annihilated” by the residents. 
  2. One lake that did not exist, that was created because of a hydroelectric dam and that is now protected as a natural reserve. 

Case study 1: “Natural to Artificial”, Phường 2, Quận 4, Ho Chi Minh City, Vietnam

I was looking for an urban lake, to study how the local residents interact with their local waters, what’s the cultural and historical relationship of Vietnamese and their water. I had the intuition that Saigon, with it’s fast growing economic activity and population might have incurred a lot of stress on such urban bodies of water.  I was interested in a small pond in Phuong 2, Quan 4 and made a quick research, found historical maps of Saigon from 1815, 1920, 1975 and today 2013: it looked like the pond had been shrinking dramatically for about a century.

1815 Saigon map 1920 Saigon Map1947 Saigon Map1975 Saigon Map1975 Saigon Map2013 Saigon map 22013 Saigon map 5

I made it into a small video, I have no rights on the original images, for research purpose only.

I wanted to verify the facts, so we scooted there. It was not straight forward to find this pond as it is literally in the residents’ backyards.  We started to get lost in the maze of the narrow streets, and started feeling awkward being the only foreigners in the area with a backpack mounted with a strange sailing robot. I was growing concerned we would not find any water. By luck, a woman came to us, speaking good english with an australian accent. She was in her 30s and walking around with her young daughter. She explained us that she was born here. That the place has changed a lot. She told us that as a child she enjoyed multiple clean ponds, in which they were playing, bathing, fishing, cleaning their laundry. She said that about 20 years ago they started using detergents for cleaning, more people came to live in the area, started to throw away their garbage in the water, plastic things. Kids would not longer play in the water and the trend became worse as many people from other cities or from the countryside -transient avid population- converged to Ho Chi Minh in hope of a better future.

What we saw was a single dark, smelly, murky stream. Semi stagnant water loaded with detritus. Some slow bubbling from the bottom of the water suggested there might still be some life still in the water.

Protei in Vietnam

Matt Corliss in Phường 2, Quận 4, Ho Chi Minh City, Vietnam.

Case study 2: “Artificial to Natural”, Hồ Trị An, Dong Nai province, Vietnam

We were  looking for a large body of water to test Protei. The sea was too far, and our prototype not quite rugged enough for the scooter ride nor for the waves. We looked at a location we could go and come back by scooter the same day. The Tri An Lake was that location.  We drove about 2 hours north and arrived on the lake. It was fun testing Protei for about one hour.

Protei in Vietnam

As you may see on the picture, there was no wind at all, the only navigation that we could do was assisted by human pull with a long line.

When we approached the lake I realised that some of the river streams had been constrained and dried out. We passed some hydroelectric installations so I deducted that we were in presence of a large artificial reserve.

Tri An Reservoir (Ho Tri An), a large artificial lake fed from the forest highlands around Dalat and created by the Tri An Dam. Completed in the early 1980s with Soviet assistance, the dam and its adjoining hydroelectric station supplies the bulk of HCMC’s electric power.
Source : “Vietnam” By Nick Ray, Yu-Mei Balasingamchow.

As I was guessing this, we passed a sign saying “Natural Reserve”. We were in presence of a man-made natural reserve.

What we learnt


  1. Protei huge side force: I was amazed when pulling Protei by its most bow point, pulling from the side, it would still be sailing forward very steadily. Great news for how much we can control the machine.
  2. Urge to make transport easier with a smaller rugged unit: as the photo underneath suggests, taking Protei on a scooter is not the safest thing we have done. At time Protei would act as a wing and destabilise the ride.  
  3. Smaller unit would mean no extra ballast needed: a smaller and lighter unit would make it so much more convenient to take on the field. The weight of the battery might suffice as ballast. We had to stop on the side of the road to add stones and sand into the lowest tube of the prototype. 
  4. Need to simplify the procedure to wire and adjust the machine: as the sun was declining, we were in panic for wiring the prototype in low light. We need to make it simpler to wire and adjust the machine as it is running.
  5. The machine needs to be more agile in low wind conditions: This region seems to be notorious for its low winds, no waves and shallow waters. If we translate that into naval architecture, that means a larger sail surface (to catch more wind), a shallower but heavier ballasted keel (for shallow water, while compensating for a larger surface of sail).

Relevancy for Vietnam environmental, health and economic challenges

My goal in this article is to identify Vietnam’s challenges and see how I/we/Protei can contribute.

It does not take long searching the internet to find the plethora of water-related issues in Vietnam. A selection of quotes and issues.

Agriculture and industry pollution damage water quality and public health:

Up to 80% of diseases in Vietnam are caused by polluted water resources, said the Ministry of Natural Resources and Environment at a ceremony in Hanoi Mar. 23 to mark the World Water Day and 60th birthday of the World Meteorological Organization. Around six million Vietnamese people have contracted one of six water-related diseases over the past four years. The expenditures for cholera, typhoid, dysentery and malaria check-ups and treatment are estimated at VND400 billion ($20.9 million). Climate change and rising sea levels will affect water resources and will be challenges for Vietnam to deal with in the coming years as the Southeast Asian country is listed among fiver countries that will be the hardest hit. Up to 1,000 communes in Vietnam’s Red River and Mekong Delta regions are facing high risks of arsenic-contained water sources. Vietnam has 180 processing and industrial zones, 12,259 healthcare facilities, 72,012 enterprises, which discharge hundreds of untreated wastewater cubic meters into its rivers a day.
Source: NGO Center 2013,


It is reported that only 39% of the rural population has access to safe water and sanitation. The rural population has moved from using surface water from shallow dug wells to groundwater pumped from private tube wells. In the Northern region of Vietnam around Hanoi, there is evidence of arsenic contamination in the drinking water. About 7 million people living in this area have a severe risk of arsenic poisoning and since elevated levels of arsenic can cause cancer, neurological and skin problems, this is a serious issue.
It is without doubt that agriculture has the largest burden on water resources in Vietnam. Vietnam is one of the richest agricultural regions in the world and a top producer and consumer of rice. Currently, water used for agriculture purposes take up over 80% of total water production. Paddy rice is the primary crop that takes up a majority of the total irrigated area. Fisheries, aquaculture, industries and services also contribute to water demand increase.
Water resources are very significant, especially natural water sources in the rural areas of Vietnam as they are the sources of economic, social and cultural activities.

Image above: Geographical connection between industrial zones and protected areas in Dong Nai River Bassin.

When it comes to the Tri An Lake that we visited, it is at the heart of the economic, health and environmental future of the country as WWF program executant Jacob Fjalland explains very well. More immediate health threat may come specifically from:

Seven strains of cyanobacteria from Tri An Reservoir, a drinking water reservoir for millions of people in Southern Vietnam, were isolated, cultivated, identified and described.
Source: “Toxic cyanobacteria from Tri An Reservoir, Vietnam”, 2010, N. Thanh Son Dao, Gertrud Cronberg, Jorge Nimptsch, Do-Hong Lan-Chi, Claudia Wiegand.

Agent Orange
We saw quite a few disabled people in the streets of Saigon. Limbless, or deformed. We asked if there was a known reason to their disability. “Agent Orange” was the immediate answer. Everybody knows about it and as tourism grows in Vietnam, the victims (not the heroes) of the war are removed from touristic area, deported outside of the city or abandoned by their families to themselves.

It is only since 2012, a few months ago, that the USA has officially started taking responsibility for Agent Orange in Vietnam and started cleaning up the horror they have spread on Vietnam.  This New York Times article by Thomas Fuller dated from August 2012 narrates how the cleanup is being implemented 4 decades too late. The World Bank publishes about the topic relevant information.
This is the areas concerned. Pretty much an entire nation intentionally poisoned.
Agent Orange spray over Vietnam 1965 1971

If you are interested, I encourage you watching this 22 minutes documentary and taking action. I take action by working on deploying Protei in Vietnam to track Agent Orange. If you are interested in helping with this, if you know the appropriate water sensors, please get in touch with me.


In June 2010, Vietnam announced that it plans to build 14 nuclear reactors at eight sites in five provinces by 2030, to satisfy at least 15 GW nuclear power (i.e. 10% share) of the estimated total demand of 112 GW. An ambitious strategy to increase the nuclear share to 20-25% by 2050 has also been outlined.


Companies including Westinghouse, AtomStroyExport, Electricité de France, and China Guangdong Nuclear Power Group (CGNPC) have all been involved in discussions about supplying nuclear plants to Vietnam, and South Korea has also expressed an interest in the project. Vietnam has signed nuclear cooperation and assistance agreements with countries including Japan, France, China, South Korea, the USA and Canada.

I will spare you videos of the health effects in Chernobyl, Pripyat after the nuclear accident.
Most nuclear power plants envisioned for Vietnam are going to exposed to a medium-level Tsunami threat. Does it ring a bell? Japan engineers are now teaching their Vietnamese peers how to secure their installations being themselves incapable of  containing the aftermath of the Fukushima disaster in their home country.

Global Earthquake since 1973 and Nuclear Power Plant locations
Above is the combined map of nuclear power plants (blue dots) and Seismic activity (heatmap), made by MapTD with data from United States Geological Survey and the International Atomic Energy Agency.

As there is no nuclear power plant in Vietnam yet, it is necessary to map the radioactivity levels in the country,  establishing a baseline for future measurements, to keep the industry in check and provide reliable data to decision makers.

Is nuclear the only way to power Vietnam? If you have the shadow of a doubt, I invite you to read the very optimistic Vietnam Atomic Energy Institute website:

Read more :

Conclusion: Protei use in Vietnam

To me the whole story is an absurd plot.

  1. In the past Vietnam has been the victim of Agent Orange and is still suffering today its horrifying effects. 
  2. In the present Vietnam is developing its industry and agriculture out of control, destroying what made its health and wealth.
  3. For its future Vietnam is determined to establish the most dangerous energy producing process predominantly on its coastline that is vulnerable to tsunami.


In the city of Saigon, we have visited a natural cluster of ponds that is being destroyed by the residents.
One hour north of Saigon we have visited a man-made reservoir that is now considered a natural reserve.
What was once a natural resource has been destroyed ; a man-made resource is now labelled “natural reserve”.
How does this make sense?

As described in this article Protei could be deployed in Vietnam for a variety of applications:

  • Measurements of agricultural and industrial pollution in water, heavy metals detection
  • Study of toxic cyanobacteria in the drinking reservoir
  • Water quality monitoring for tourism in lakes and on the shore
  • Agent orange tracking in lakes to avoid further contamination
  • Radioactivity baseline mapping before installation of power plants
  • Earthquake and tsunami alert system offshore (Vietnam initiated it’s own tsunami alert system in 2011

According to the discussion we had with local entrepreneurs, bureaucracy and the process of getting permission may slow down our progress. On the other hand Vietnam has a fast growing educated population that is made of curious, hard working young minds. We have been advised to focus on educational channel and working in harmony with local authorities to build trust and capacity. Protei INC manufacturing is going to be located in the Hong Kong region, not far at all from Vietnam, so we hope to be back in the region soon.

“Croire, Douter?”, Believe or Doubt? What is the future of Vietnam? What is certain is that Vietnam, the small Asian Dragon will keep growing. What we do not know is how it will grow. Vietnamese people are admirably resilient and resourceful people. Will they destroy their country trying to make it “great”? Does sustainable growth even exist?

We may become the makers of our fate when we have ceased to pose as its prophets.
Source: Karl Popper

20130130 Protei and Safecast in Fukushima

Departure from Yoyogi

Last winter, thanks to the help of my dear friend Hiroshi Nomura and his family, Mako Mochizuki, the bicycle of Tom Nagashima and the dosimeter  from Greenpeace Japan, I cycled from Tokyo to Sendai measuring radioactivity, looking for the best location to deploy a fleet of Protei from the shoreline. This map below is my journey last year ending in TEDxTohoku.

View Tokyo -> Sendai. Radioactivity measures + pictures in a larger map.
I based my trip on the first estimate of radiation dispersion, and the most recent Safecast map.  I failed at working with Safecast, even if I was lucky to bump into Kalin on the road last year who instructed me of how to use the dosimeter and the geiger counter.

A year ago, I saw devastation on hundreds of kilometers of coastline. I met fishermen at the refugee camp that told me terrifying stories of earthquake, tsunami and radioactivity. To remind you a few facts : on 11 March 2011, a magnitude 9.03 (Mw) undersea megathrust earthquake about 70km off the coast of Japan that occurred at 14:46 JST (05:46 UTC). Tsunami waves reached heights of up to 40.5 metres (133 ft) in Miyako in Tōhoku’s Iwate Prefecture and which, in the Sendai area, travelled up to 10 km (6 mi) inland. 15,878 deaths, 6,126 injured and 2,713 people missing from the earthquake and tsunami alone. The tsunami caused nuclear accidents, primarily the level 7 meltdowns at three reactors in the Fukushima Daiichi Nuclear Power Plant complex, and the associated evacuation zones affecting hundreds of thousands of residents. The World Bank’s estimated economic cost was US$235 billion, making it the costliest natural disaster in world history.

According to the Woods Hole Institute, the Fukushima Nuclear plant accident “resulted in the largest accidental release of radiation to the environment in history” – if you want to understand how it compares to Chernobyl, please have a read at this informative poster.

I found several sites that would be good to launch a fleet of Protei from, and potentially sail around Fukushima to measure radioactivity. So I had to come back. This time with Gabriella Levine, and a Protei to test in the water, more prepared. We arranged a meeting with Joe Moross of Safecast.

Hacking a custom Geiger counter before driving all the way to Fukushima with Safecast

After a brief discussion we came to the conclusion that making underwater measurements was a research worth attempting. The other information was that water generally acts as “a shield”, and being many times denser than air, radioactivity tends to get “diluted” in the “mass of water”. So we decided to attempt measuring radioactivity on the seafloor. That would mean getting our sensor underwater, very close to the seafloor.
We ran to Akihabara with Prof Alvaro Cassineli of Tokyo University and spent most of our night hacking at the Safecast headquarters in Shibuya (picture above).


After a few hours of sleep, and before hitting the road, we stocked up some cute radioactive cake. Please have a slice :)


In the car, the co-pilot would get near-real time radioactivity informations and guide instructions to the driver from Tokyo to Fukushima, and later down from Fukushima to Kyoto trying to take yet unmapped / un-measured routes. We encountered snowy or icy road in the mountains that slowed down our progression.

Safecast Pinup on red car
Fukushima Disaster, firetruck wreck

The Safecast shiny red car took us all the way to Fukushima, where we found this wreck of a red fireman truck. Stark contrast.Fukushima ruins, after the tsunami

I knew we would come across brocken houses, but I can never get used to it…

Protei visits disaster area near Fukushima

We were everywhere reminded that nothing can resist the power of nature. “Tsunami Barrier” is an oxymoron. No matter how hard we try.

Fukushima underwater test area

We arrived in Hisanohama, which is just south of the new exclusion zone. Exact location map.

We tested Protei v10.4 in the water. The electro-mechanics are working well but it lacked ballast (weight at the bottom of the keel) : the wind flattened it on the water and careless transport later broke the mast. We’ll work on the build again soon. Because we were in Fukushima, we focused not on Protei itself but on the radioactivity sensing part.

We tested our freshly built underwater geiger counter up to 6 meter depth without leak nor damage to the sensor.


This is our kit of underwater radioactivity measurement. It fits nicely in a bag, with our ~5kg lead weight.
From left to right :


What we measured the 2013 01 30, at Hisanohama port (XY = 37.1480, 141.0029) :

  • 0.224μSv in the air in HisanoHama
  • 0.002μSv midwater (3m depth)
  • 0.09μSv at the sea bed (3cm from sensor to sea bed) (6m depth)

other measurements we made, for indication :

Experimental set up

20130130 Hisanohama underwater radioactivity measurements - Protei + Safecast

And below is a very rough draft of what Protei could provide : autonomous sensor deployment for surface, “mid-water” and seabed radioactivity measurements.

Proposition for future work

20130215 Protei proposition for surface and underwater radioactivity measurements

We haven’t done enough background research about how radioactivity in the ocean is currently studied, but  we feel that the difference in values between

  • land surface
  • water surface
  • “mid-water”
  • seabed

are significant enough to make us want to investigate the topic further in partnership with Safecast.
Hundreds of thousands of people have suffered the earthquake, tsunami and on-going nuclear crisis. We feel such research is extremely valuable for the life of people, the future of Japan and other countries equipped with nuclear equipments and waste facilities. We don’t know yet what would be the value of a map of seafloor radioactivity similar to the one the Woods Hole researchers have been developing for surface water (below). I believe these would be 2 very complementary data sets and would help us understand much better radioactivity in the oceans in general. Such Protei deployment could also be used in other “Radioactive waters” which are not necessarily consequent to nuclear accidents in Africa and the Middle east (must read article).

As we are sailing around the world, we are making radioactivity measurement everywhere we go. Maps will come :)

Safecast + Protei

A million thanks to Safecast and Tokyo University Department of Applied Physics.
We’ll be back !!!