Radioactive water has leaked out of Japan's crippled nuclear reactors and into the Pacific Ocean. Living on Earth's Bruce Gellerman talks with University of Michigan nuclear engineering professor Kimberlee Kearfott, about how the radioactive water might affect marine life.
CURWOOD: From the Jennifer and Ted Stanley Studios in Somerville, Massachusetts, this is Living on Earth. I'm Steve Curwood.
GELLERMAN: And I'm Bruce Gellerman. Despite heroic efforts by workers at the Fukushima nuclear power plant in Japan, at least one containment vessel has ruptured and radiation is spreading.
To cool the reactors and spent fuel rods, workers continue to pump and pour tons of water on the ruins. But radioactive steam has escaped into the air and radioactive water is finding its way into the ground and flowing into the Pacific Ocean. Kimberlee Kearfott is a professor of Nuclear Engineering and Radiological Sciences at the University of Michigan. Hello Professor!
KEARFOTT: Hi Bruce!
GELLERMAN: So, professor, what happens when you put radioactivity into water, into the ocean - what happens to it? What happens to the water?
KEARFOTT: What happens is very complicated. And it depends both on physics, chemistry, and biology. It won’t change the water, per se, but it gets transported around the planet in interesting and complicated ways. There’s a large current similar to the Gulf Stream called the Japan Stream, and this is a very strong current that runs from the east coast of Japan all the way to Alaska. The main Japan Current turns east well before it reaches Fukushima. Even if fish got into that stream and were carried up to Alaska, that dilution would be high.
Kimberlee Kearfott is a professor of Nuclear Engineering and Radiological Sciences at the University of Michigan. (University of Michigan)
GELLERMAN: Well you have, yeah, the old saw, “The solution to pollution is dilution.” You got the biggest diluter in the world - you got the Pacific Ocean.
KEARFOTT: That’s correct! The Pacific Ocean has about 200 billion, billion gallons of water in it. That’s a lot of water. But physics isn’t everything. There’s also a little bit of biology at play.
GELLERMAN: What would these radioactive particles do to the biota of the ocean?
KEARFOTT: Marine life can accumulate or concentrate some chemicals. An example is mercury in fish. This is a rather extreme example. Although the levels of mercury in water may be very low, they can reach significant levels in fish.
Iodine is something that’s concentrated in seaweed and shrimp. Caesium has also been found to concentrate in sea life. Strontium, which is a bone-seeking radionuclide in humans, can concentrate in the shells of seafood. So it depends on what the form is, the chemical form, but also what is going on with the food chains.
Radionuclide could get into algae. Little fish could eat the algae. Bigger fish could eat the little fish. And pretty soon you have a fair amount of radioactivity in a given organism. Generally, however, fish and other organisms are less sensitive to radiation then humans are.
The Tsukiji fish market is the biggest wholesale seafood market in the world. It has been closed or restricted since the March 11 earthquake and tsunami. (Photo: Josh Berglund)
GELLERMAN: What would happen if I ate one of those fish?
KEARFOTT: Because there would still be a lot of dilution, we would not be talking about you getting radiation sickness or radiation syndrome. Here we would have a case of lower level health effects. Those effects would include a risk of cancer and a risk of genetic defects.
We’re only talking in terms of risks, and the total risk depends upon the total amount of seafood that you eat and also how contaminated that seafood is. In general, risks are so small that we can only calculate them. We can’t go and count that there were 15 of this type of cancer caused by exposure to radiation. There are a lot of uncertainties associated with those calculations.
GELLERMAN: Could this stuff get into the groundwater and the aquifers in Japan?
KEARFOTT: Yes it could, given enough time. That’s what’s on our side with groundwater…is that there’s time to figure out where any radioactive water is, and time to attempt to intervene.
GELLERMAN: I know in Chernobyl what they did is they had coal miners dig under the reactor and then inject liquid nitrogen and froze the ground so that they would prevent the radionuclides and radioactivity from getting into the groundwater.
KEARFOTT: That is one approach. There are also new chemicals that have been developed since Chernobyl that could be laid down that would bind to the radionuclides and prevent them from moving so much in the environment.
GELLERMAN: Any advice for what the Japanese can possibly do at this point?
KEARFOTT: I’m very concerned about the people of Japan. If there are additional airborne releases, my advice would be: don’t drink rainwater. Public water supplies would be much more diluted in terms of the radionuclides in them. If someone is taking rainwater and drinking it, their risk may be much higher than that of tap water.
I’m not worried, sitting here in the United States, about my own personal safety. It’s simply not conceivable that we would have radionuclides here that would be high enough to pose a health risk to anyone in the United States.
GELELRMAN: Well, Professor Kearfott, thank you so much, I really appreciate it!
KEARFOTT: You’re very welcome, Bruce!
GELLERMAN: Kimberlee Kearfott is a professor of Nuclear Engineering and Radiological Sciences at the University of Michigan.
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