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Fukushima update: local contamination of power plant area under scrutiny

Here’s a very brief update on events as of tonight at the Fukushima Daichii power plant in Japan. Overall, "the situation remains very serious," the International Atomic Energy Agency (IAEA) reiterated at a briefing today.

To recap briefly on past events; concerns focus on reactors 1 to 3, all of whose cores seem to clearly have undergone meltdowns to greater-or-lesser extents, and which have already released radioactive material during venting to the atmosphere — carried out to release pressure in the containment vessels. Electricity supplies have not yet been established to their permanent coolant systems, so emergency injection of water using temporary pumps is still being relied upon. At reactor 4, concerns are different — the reactor’s core had been transferred to a cooling pond during reactor maintenance at the time the quake and tsunami hit, leaving the core’s fuel rods — lacking a containment vessel — exposed directly to the air when water levels in the pool fell and fuel rods overheated; water injection has since stabilized the pool.

There have been few new developments today in the status of these 4 reactors, but here are quick summaries of some other related developments. Many of these are related to local pollution around the site, resulting both from the accidents themselves and from collateral damage resulting from the desperate efforts to cool the reactors, and prevent full-scale meltdowns.

First reported groundwater contamination:

Kyodo News are tonight reporting

that the first groundwater contamination at the Fukushima power plant has been detected. It cites levels 10,000 times the legal limits. This is just a heads up; more later when I get some data. The risk of groundwater contamination has been high on people’s minds since the discovery last weekend of large volumes of highly radioactive water — some of it extremely radioactive — in the basements of the plant’s reactors, and in large trenches outside of the reactors — see my article in Nature this week, for more on this, and more quantitative data — Radioactivity spreads in Japan.

Seawater contamination: The key point here seems to be that whereas much of the initial offshore radioactive pollution was caused by deposition from the large atmospheric plumes of radioactivity released, local marine pollution now seems to be being continually fed from near shore local release emanating from the plant’s discharge channels. The IAEA reported tonight that:

“The latest analyses in seawater 330 m south of the discharge point of NPP Units 1-4, and 30 m north of the discharge point of Units 5-6 were made available for 29 March. In particular readings of 130 000 Bq/l of I-131, 32 000 Bq/l of Cs-137 and 31 000 Bq/l of Cs-134 were reported near Units 1 – 4.”

These are almost double figures reported by IAEA earlier this week: that radioactivity levels near the plant’s discharge pipes were increasing, with 74,000 Bq l−1 of iodine-131 and 12,000 Bq l−1 of caesium-134 and caesium-137 combined. Recommended maximum coastal discharges from nuclear power plants are typically lower than 4,000 Bq l−1.

As I’ve pointed out before, marine readings can vary widely depending on currents and discharge rates; what’s worrying though most of all is not the variation in the readings but that high levels of radioactive discharges from the plant to the sea are continuing unabated. The IAEA has a French group from Toulouse, Sirocco, doing modelling of where that marine radioactivity might go, but it’s results so far seem fairly preliminary.

Japan is already busy dealing with the after-effects of a huge quake and tsunami, and now a nuclear disaster, and although IAEA and other international agencies are on the job, I’m still a bit surprised at how little we are hearing of any organized international academic efforts to urgently bring top academic scientific expertise to bear on helping plan and execute such essential monitoring work at sea and on land, as well as the many other epidemiological and other studies that could inform efforts — if you are a scientist involved in such, do get in touch with me at

And the data coming out, while fairly transparent on the whole — by past nuclear industry standards — are often disparate, poorly organized, incomplete, in multiple units lacking context or explanation, and in clumsy formats such as pdfs that make independent machine-readable data analysis difficult — in Web terms, the ways in which data are generally being made available publicly in response to this crisis look much like the 1990’s Web, rather than the 21st century Web of web services and real-time mapping. Data may not seem an immediate priority, given the scale and urgency of the crisis, but clearer information and data would without any doubt help alleviate the obvious confusion that is currently being experienced by many, not surprisingly concerned, Japanese, and others, as to the ongoing consequences of this nuclear accident, and also spur scientific analyses by the broader research community worldwide. Public and scientific data dissemination is an essential part of emergency planning, but so far the authorities involved, including IAEA, are falling short of what’s needed.

ISIS report slams data collection at Fukushima-Daichii plant: The Institute for Science and International Security, a fairly well-respected body in nuclear nonproliferation work has tonight released a Preliminary Assessment of Accident Sequences and Potential Atmospheric Radiation Releases. I found its painstaking analysis of radiation readings from the plant itself, and their shortcomings, a useful new analysis.

Other snippets from today’s IAEA briefing:

Radiation measurements in Tokyo: “Two IAEA teams are currently monitoring radiation levels and radioactivity in the environment in Japan. On 30 March, one team made gamma dose-rate measurements in the Tokyo region at 7 locations. Gamma-dose rates measured ranged from 0.03 to 0.28 microsievert per hour, which is within or slightly above the background.”

Food: “Since our briefing of yesterday, significant data related to food contamination has been submitted by the Japanese Ministry of Health, Labour and Welfare. Seventy-six samples were taken from 28-30 March, and reported on 30 March. Analytical results for 51 of the 76 samples for various vegetables, fruit (strawberry), seafood (sardines), and unprocessed raw milk in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Niigata, Saitama, and Yamagata), indicated that iodine-131, caesium-134 and caesium-137 were either not detected or were below the regulation values set by the Japanese authorities. However, it was reported that analytical results in Fukushima prefecture for the remaining 25 of the 76 samples for broccoli, cabbage, rapeseed, spinach and other leafy vegetables, indicated that iodine-131 and/or caesium-134 and caesium-137 exceeded the regulation values set by the Japanese authorities.”

Drinking water: "Most of the previously imposed recommendations for restrictions on drinking have been lifted. As of 28 March, recommendations for restrictions based on I-131 concentration remain in place in four villages of in the Fukushima prefecture, in three of these villages, restrictions continue to apply for infants only.”

For full coverage of the Fukushima disaster, go to Nature’s news special.


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