Tag Archives: Cesium

Cesium, Fukushima, Japan, Marine Life, Peer Reviewed, Strontium

Radioactive Strontium and Cesium in Fish From the Harbor at the Fukushima Dai-ichi Nuclear Plant

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By Jay T. Cullen

The purpose of this post is to report on a recent peer-reviewed study that investigated the radionuclide content of fish caught in the harbor of the Fukushima Dai-ichi Nuclear Powerplant (FDNPP) in 2012 and 2013. The post is also written in part to address questions like:

Why don’t you measure 90Sr in fish you catch off of North America?

This post is part of an ongoing series dedicated to summarizing results from scientific research into the impact of the FDNPP disaster on the environment. Fujimoto and colleagues measured the activity of Cesium-134 (134Cs half life ~2 years), Cesium-137 (137Cs half life ~30 years) and Strontium-90 (90Sr half life ~29 years) in fish collected from the FDNPP harbor and just outside the port in 2012 and 2013. Fish were most contaminated in the harbor and had radiocesium activity concentrations (in whole body without internal organs, Bq kg-1 – wet weight) that were ~200-330 times higher than measured 90Sr levels. The much lower 90Sr levels compared to radiocesium in the fish is consistent with much lower releases of 90Sr to the Pacific Ocean compared to radiocesium in the aftermath of the meltdowns at FDNPP (see here, here and here for example). The activity of radiocesium in fish diminishes dramatically with distance from the harbor and as of April-June 2015 none of the fish caught in Fukushima prefecture waters exceeded the stringent 100 Bq kg-1 Japanese safety standard. Across the Pacific, we have yet to detect Fukushima derived radiocesium in salmon and steelhead trout caught in British Columbian waters as part of the Fukushima InFORM monitoring effort. 90Sr is much more difficult and costly to analyze in environmental samples than are the cesium isotopes. The results of the Fujimoto study suggest that 90Sr from Fukushima is unlikely to be found at detectable levels in marine organisms in the northeast Pacific and that resources to monitor the impact of the disaster on our marine environment should focus on the detection of the cesium isotopes. Continue reading Radioactive Strontium and Cesium in Fish From the Harbor at the Fukushima Dai-ichi Nuclear Plant →

Monitoring, Oceanic

Sampling for Fukushima Derived Radionuclides in the Northeast Pacific and Arctic 2015

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By Jay T. Cullen

Bow of the CCGS Laurier. Great ship and crew for science operations in the Arctic.
The purpose of this short post is to update readers on the activities of the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project. This post is the most recent in a series documenting scientific research into the impact of the Fukushima Dai-ichi disaster on environmental and public health. Today the icebreaker CCGS Sir Wilfrid Laurier will leave Victoria BC bound for Dutch Harbor Alaska and then up through Bering Sea and Strait to the Arctic Ocean. On the way the InFORM project will collect surface seawater to characterize the distribution of Fukushima derived radionuclides 137-Cesium (137Cs half life ~30 years), and 134-Cesium (134Cs half life ~2 years). As in previous years this information will help to determine how well model predictions of the activities and progression of ocean borne contamination across the Pacific Ocean match with observations. This provides important information on the impact of this contamination on the health of the Pacific ecosystem and the North American public that rely on the ocean for their food, livelihood and recreation. The evolution of the contaminant plume in time and space also helps the scientific community to better understand ocean mixing which is a key parameter toward understanding the oceans role in mitigating atmospheric greenhouse gas increases and climate change. Continue reading Sampling for Fukushima Derived Radionuclides in the Northeast Pacific and Arctic 2015 →
Cesium, Fukushima, Iodine, Japan, Peer Reviewed

Status of the Spent Fuel At Fukushima Dai-ichi: How much was released to the environment?

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By Jay T. Cullen

The purpose of this post is to answer the question posed in the title by summarizing a recently published peer reviewed study in the journal Nuclear Engineering and Design. The diary is part of an ongoing effort to communicate results from scientific studies aimed at understanding the impact of the Fukushima Dai-ichi meltdowns on the environment. The paper by Jäckel compares measured and predicted activities of reactor products 134-Cesium (134Cs half life ~2 years) and 137-Cs (137Cs half life ~30 years) in the reactor cores and spent fuel to measurements in the spent fuel pools (SFPs) of Units 1, 2, 3 and 4 at the site to determine how much spent fuel radiocesium was released after the accident. The comparison indicates that only very minor damage to the spent fuel occurred during the accident and subsequent clearing work such that at most about 1% of the Cs inventory from a single bundle (in Unit 2 SFP) was released to the cooling water. The short answer to the question is that not very much of the spent fuel was released at all and the bulk of releases originated from the reactor fuel in Units 1, 2 and 3 at the time of the accident. This is consistent with the results of measurements made of Fukushima derived radionuclides in air, soil and water worldwide since March 2011. Continue reading Status of the Spent Fuel At Fukushima Dai-ichi: How much was released to the environment? →

Biota, Monitoring

Analysis of Beached Grey Whale in British Columbia for Fukushima Radioisotopes

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By Jay T. Cullen

Grey Whale being dissected on Wickaninnish Beach April 23, 2015 (The Whale Centre)

The purpose of this post is to report analyses carried out by the InFORM project on muscle and blubber samples from a grey whale (Eschrichtius robustus), that beached near Tofino, BC on April 20, 2015. The post is the most recent in a series that aims to communicate results of scientific research into the impact of the Fukushima disaster on the environment. With the cooperation of the Ucluelet Aquarium the InFORM project was able to obtain samples of the whales muscle and blubber which were analyzed for the presence of gamma emitting radioisotopes in Health Canada’s laboratories in Ottawa, ON Canada. The gamma radiation spectra were dominated by naturally occurring radioisotopes, primarily Potassium-40 (40K half life 1.25 billion years), and after 24 hours of counting no Fukushima derived Cesium-134 (134Cs half life ~ 2 years), a fingerprint of the disaster in the environment could be detected. The unfortunate demise of the grey whale is very unlikely to have been the result of acute or chronic radiation exposure owing to Fukushima derived radionuclides in seawater and the whales food. Continue reading Analysis of Beached Grey Whale in British Columbia for Fukushima Radioisotopes →