Nature‘s Great Beyond blog has been one of my favorite sources for information and analysis of the Fukushima nuclear crisis. They’ve put together a four-minute video succinctly summarizing the events to date, as well as the challenges and opportunities ahead.
Two quick updates on the current situation at Fukushima:
On Sunday, officials with the Tokyo Electric Power Co. released a 63-point strategy for final resolution of the crisis. One crucial step is removing highly radioactive water that has pooled in basements and trenches. That process has begun, but is expected to take weeks or months to complete. Officials say the water is 2 million times more radioactive than the water released into the ocean earlier this month.
Meanwhile, the Japanese government has implemented a formal ban on entry into the 20-kilometer evacuation zone around the Fukushima Dai-ichi nuclear power plant. Some residents have ignored warnings to stay away from the area.
I’ve been trying for weeks to get Dr. Ken Buesseler of Woods Hole Oceanographic Institution on Climatide for a live chat about the impacts of the Fukushima nuclear crisis on marine life, and how he studies radioactivity in the ocean. It hasn’t been in the cards. But he did make an appearance on WCAI’s The Point with Mindy Todd last week. Take a listen:
In 1986, reactor 4 at the Chernobyl nuclear power plant exploded, creating the worst nuclear accident in history. Today, Japanese officials upgraded the Fukushima crisis to a level 7 rating - matching Chernobyl.
The big news from Fukushima today is the fact that officials are upgrading the disaster from a 5 to a 7 (out of 7) on the international rating scale for nuclear accidents. Chernobyl was also a level 7 “major accident,” while Three Mile Island was rated a level 5 “accident with wider consequences.” But that may be the end of the similarities, according to Hidehiko Nishiyama, spokesman for Japan’s Nuclear and Industrial Safety Agency.
“It is quite different from Chernobyl,” said Mr. Nishiyama. “First, the amount of released radiation is about a tenth of Chernobyl,” he said, adding that while there were 29 deaths resulting from short-term exposure to high doses of radiation at Chernobyl, there were no such deaths at Fukushima.
There are fundamental differences between the two incidents. In the case of Chernobyl, a reactor actually exploded:
… a graphite fire burned uncontrolled for days, spewing out radioactive smoke that spread around the world. Fukushima, unlike Chernobyl, has a containment structure, which, even if damaged, has meant that the Japanese accident has shown “much, much, much lower” traces of far-flung radiation, Wolfgang Weiss, chair of the United Nations Scientific Committee on the Effects of Atomic Radiation, said in Vienna last week.
Geoff Brumfiel points out that the timescales of the two crises are totally different. Nearly a month after the earthquake and tsunami that crippled the Fukushima plant, steam continues to rise from the reactors, contaminated cooling water is still leaking and flooding some parts of the facility, and experts say it could take months to staunch the flow. So the total radioactivity released by Fukushima could eventually surpass Chernobyl.
And then there’s the fact that highly radioactive water has been flowing directly into the adjacent ocean, resulting in levels of radioactive iodine and cesium millions of times over the legal limit – and thousands of times higher than seen in the Black Sea after Chernobyl.
Northeastern Japan was devastated by a magnitude 9.0 earthquake and 10 meter tsunami on March 11th. Numerous aftershocks - including a magnitude 7.1 earthquake this morning - have triggered further tsunami warnings.
First things first: What follows is essentially a thought experiment, nothing more.
Following a magnitude 7.1 earthquake off the northeastern coast of Japan (the latest of many aftershocks), tsunami warnings were issued for much of the same coastline devastated by the March 11th tsunami. Warnings were for a 1 meter tsunami in Fukushima. Those warnings have now been lifted, and there have been no new reports of damage to the crippled Fukushima Dai-ichi plant. So (further) disaster seems to have been averted. Here’s where the thought experiment comes into play.
My first thought when I saw the warnings was: “Oh god, a radioactive tsunami!” Alarmist? Maybe. I sent a few feelers around Twitter to see if anyone else was thinking along the same lines, then picked up the phone and called Dr. Ken Buesseler, an oceanographer right up the road at Woods Hole Oceanographic Institution who studies radioactivity in the ocean (and, consequently, has been a very busy man the past few weeks). I ran my nightmare scenario past him: were we looking at highly radioactive seawater washing over Fukushima prefecture?
While that has obviously not come to pass, the conversation yielded some surprising insights and perspective that seemed worth sharing, despite their purely speculative and theoretical nature.
Short answer: no. First off, a 1.5-3 foot rise in water levels wouldn’t go very far in that region. And high levels of radioactivity in seawater appear to be highly localized, falling by a factor of a thousand within just 1,000 feet. Levels 19 miles offshore are a million times lower than at the point of discharge. So Buesseler reasoned that the grounds of the Fukushima Dai-ichi plant itself would be the area most likely to be over-washed with radioactive seawater.
Given how contaminated the grounds of the Fukushima Dai-ichi plant are, and the fact that a tsunami would mix highly radioactive near-shore water with offshore waters where radioactivity has been greatly diluted, Buesseler further speculated that tsunami water would actually be less radioactive than the area it would wash over. He said he would actually be more concerned about the additional radioactivity the seawater would pick up and wash back into the sea – both from the ground, and from open pits holding the most highly radioactive waste water.
Above all else, though, Buesseler said the primary concern has to be the possibility of further structural damage and/or (re)loss of power due to another large earthquake or tsunami.
Levels of radioactive iodine in seawater surrounding the crippled Fukushima Dai-ichi nuclear power plant skyrocketed late last week, reaching 7.5 million times the legal limit on Saturday. Over the weekend, plant operators announced they had found the leak allowing highly radioactive water to flow directly into the ocean. Today, the Associated Press is reporting that the leak appears to be plugged. It took a few tries; 400 gallons of sodium silicate seems to have done the trick. But officials remain cautious:
While officials have said the crack in a maintenance pit plugged early today was the only one found, they have not explicitly ruled out that radioactive water is leaking into the sea from another point.
“Right now, just because the leak has stopped, we are not relieved yet,’’ said chief Cabinet secretary Yukio Edano. “We are checking whether the leak has completely stopped, or whether there may be other leaks.’’
Experts have maintained that the vast volume of the ocean will dilute radioactive iodine to levels low enough to not cause significant ecological damage beyond the area immediately surrounding the plant. Samples taken a couple of weeks ago showed radioactivity levels 19 miles offshore were a thousand times lower than near the coast. Experts also stress that radioactive iodine is relatively short-lived and will decay to background levels within a few months.
Still, radioactive iodine can be concentrated in seaweed and fish and does pose a serious human health risk if consumed. Widespread concern about seafood contamination has prompted Japanese officials to set new safety guidelines. They also admitted that “some fish caught last week about 50 miles from the plant would have exceeded the new safety limits, which may change as circumstances do.”
The good news about the plugged leak is tempered by an warning from U.S. government engineers that troubles at the plant are likely far from over. The NY Times reports that the detailed technical assessment cites further explosions and deterioration of containment structures as possibilities. Some of the actions recommended by the U.S. engineers are underway, including attempts to remove seawater residues and inject nitrogen into containment structures to reduce the risk of hydrogen explosions.
High levels of radioactive iodine have been detected in seawater near the crippled Fukushima Dai-ichi power plant in Japan.
Since the very beginning of the nuclear crisis in Japan, it’s been clear that some portion of the radioactive material released into the atmosphere would make its way into the ocean as fallout. But there’s new evidence that radioactive elements are leaking directly into the Pacific Ocean around the Fukushima Dai-ichi power plant. Numerous media outlets are reporting that, in the past few days, radioactive iodine has been found in seawater just north of the plant at levels 1,150 times the legal limit, nearly ten times levels detected a week ago. Radioactive iodine levels in the ocean just south of the plan were found to be more than 1,850 times the legal limit. It’s still unclear what this leakage indicates in terms of damage to the nuclear reactors.
Radioactive iodine impacts
Radioactive iodine is an immediate concern for human health because it accumulates in the thymus and can increase the risk of cancer, particularly in individuals exposed at a young age. That’s why there’s so much attention being devoted to tracking contamination of spinach, milk, and drinking water supplies in Japan. However, at this point, there seems to be broad agreement among experts that the iodine released from Fukushima Dai-ichi does not pose a major threat to people outside of Japan or to marine life. Here’s why:
Iodine-131 (the official name for radioactive iodine) decays fairly quickly; it has a half-life of just 8 days, meaning that half of the radioactivity is gone after eight days. Even for large releases, radioactive iodine levels would be expected to fall to background levels within a matter of weeks to a few months.
As iodine-131 is whisked around the globe on atmospheric air currents, it quickly becomes diluted. While low levels of radioactivity from Fukushima Dai-ichi have been detected in air and rainwater around the U.S. (even here in Massachusetts), the E.P.A. stresses that levels are thousands of times below even conservative levels of concern.
That’s even truer in the ocean. Oceanographer Ken Buesseler of Woods Hole Oceanographic Institution says that radioactive material would quickly become mixed throughout the top 300 feet of the ocean, then carried around the Pacific Ocean on currents. Buesseler says that, even after Chernobyl, the Black Sea remained safe for both swimming and seafood consumption, and there were no noteworthy impacts on marine life.
The U.S. Food and Drug Administration has said that it is monitoring seafood, milk, and produce imported from Japan, but doesn’t expect contamination problems. Besides, the fishing fleet and shipping infrastructure in northeastern Japan was devastated by the earthquake and tsunami, severely limiting the availability of food products from the affected region.
One possible exception would be seaweed from the area immediately around the crippled plant. Seaweed contains high levels of iodine, so could concentrate the radioactive iodine. Again, this is a relatively short-term concern, primarily in Japan.
Radioactive cesium and plutonium
Of course, Iodine-131 is not the only radioactive material being released from the reactors at Fukushima Dai-ichi. Radioactive cesium-137 has been found in seawater near the plant, albeit at much lower levels than radioactive iodine. Cesium-137 is much longer-lived than iodine-131; it’s half-life is 30 years, so it could be around for hundreds of years, making it the greater threat to marine life. However, at this point, levels of cesium-137 in seawater around Fukushima are similar to levels seen in the Black Sea after Chernobyl where (as I mentioned above) scientists saw no serious impacts on marine life.
Questions about plutonium are also surfacing. Traces of plutonium have been found in soil samples around the nuclear power plant, and the contamination appears to have originated from the current crisis. Plutonium has a half-life of more than 24,000 years and is very dangerous if inhaled or ingested, but its radioactivity can’t penetrate skin or clothes and the levels found in the soil samples were too low to pose a human health risk. But Hidehiko Nishiyama, an official from Japan’s nuclear safety agency, has been quoted as saying that “While it’s not at a level harmful to human health, I am not optimistic. This means the containment mechanism is being breached, so I think the situation is worrisome.”
Obviously, this crisis is far from over. Normal operations have not been restored (or, alternatively, permanent containment solutions implemented) and new contamination is being discovered almost daily. Still, at this point, it appears that the environmental and human health impacts of the Fukushima Dai-ichi nuclear crisis will likely be limited to the surrounding area in Japan with by far the heaviest burden falling on plant operators.
We’re getting a better idea of how much radioactive material has entered the ocean around Japan’s crippled Fukushima Dai-ichi nuclear power plant. Bloomberg reports that damaged fuel rods have released five different kinds of radioactive material and contaminated nearby seawater:
Iodine-131 was detected at 127 times normal levels from sample water taken at 2.30pm yesterday, while caesium-134 levels were 25 times normal and caesium-137 was at 17 times normal, Tepco said on its website.
Ken Buesseler of Woods Hole Oceanographic Institution told Bloomberg that radioactivity levlels
“This time of year off the coast of Japan, they would mix with water down 100 feet to 300 feet, and be diluted by a factor of about 100. The currents there would move it to the south, just north of Tokyo, and then out to sea.”
The ocean’s vast capacity to dilute out the radioactive material means that the nuclear crisis is unlikely to impact ocean life or create a seafood safety issue. As Ken told me last week, the Black Sea remained safe for swimming and eating seafood despite Cesium-137 levels 10-20 times normal after Chernobyl. Localized contamination of seaweed with radioactive iodine could be a concern for Japanese consumers, but iodine decays rapidly and will be gone within a month.
“But my advice would be not to eat seafood caught from within the evacuation and sheltering zone,” or about 30 kilometers offshore, Camplin said in an e-mail. “Effects on wildlife in the sea are unlikely to be severe.”
The U.S. Food and Drug Administration is attempting to reassure American consumers about the safety of imported seafood, saying it is monitoring the situation closely:
Based on current information, there is no risk to the U.S. food supply. FDA is closely monitoring the situation in Japan and is working with the Japanese government and other U.S. agencies to continue to ensure that imported food remains safe.
This satellite image from March 17, 2011, shows damage to nuclear reactors at the Fukushima Dai-ichi nuclear power plant in Japan caused by a magnitude 9.0 earthquake, the resulting tsunami, and subsequent explosions and fires caused by lack of cooling.
If there’s been a saving grace in Japan’s nuclear crisis to date, it’s been the weather. With the exception of recent precipitation pulling some radioactive material down to the ground near the Fukushima Daichi plant, offshore breezes have been pushing most of the radioactive material out to sea. That could be a lifesaver (literally) for the residents of northeastern Japan. But what does it mean for the billions of creatures who inhabit the Pacific Ocean?
To answer that question, I got in touch with Dr. Ken Buesseler, a scientist at Woods Hole Oceanographic Institution who has actually used radioactivity from Chernobyl and nuclear testing in his research tracking chemical processes in the ocean. I asked him if we have a handle on what the situation in the western Pacific is right now in terms of types and levels of radioactive material. Short answer: NO.
We have no data on fallout to the Pacific Ocean, other than they have said that releases include Iodine-131 and Cesium-137… Iodine-131 has a short half-life (8 days) and is gone in a month but is of more immediate exposure concern due to its uptake in the thyroid particularly by young children. Cesium-137 has a longer 30 year half life, so that will still be around after decades.
Where in the world – and ocean – radioactive material from Japan will end up depends largely on wind and weather conditions. As Jeff Masters explained recently on Wunderblog, the high pressure system that has been driving the offshore winds has also likely kept radioactive material close to the ocean’s surface, increasing the chances that much of the material will be deposited into the Pacific rather than whisked around the world on the air currents higher in the atmosphere. Continue reading →