A local nuclear engineer who is also a UMass-Lowell professor said this week that the situation with the damaged nuclear plants on the East Coast of Japan is changing so fast it's hard to know exactly what's happening or how it will end.
"It's a dynamic situation," Dr. Gilbert Brown said Monday afternoon. He noted then that it appeared the nuclear power plants damaged by the earthquake and ensuing tsunami had been stabilized by workers on the ground pumping in seawater to cool down the radioactive fuel rods.
He said then that it appeared power company employees had stemmed a full-blown meltdown.
But all that changed Monday night, when there was a third explosion in one reactor followed by a fire at another reactor at the 40-year-old General Electric model Fukushima I Nuclear Power Station.
It appears now that the fuel rods may have experienced some melting, meaning that a meltdown is, indeed, in progress.
The question, Brown said yesterday, is how far it will go and what will happen if there is a full meltdown.
"It's still a challenge for the guys trying to keep water in the vessel and keep the containment building intact," Brown said. "It's obvious there's been a lot of fuel damaged."
In addition, varying amounts of radiation have been detected in and around the power plant, while the evacuation zone has been expanded. As of 1:30 p.m. Eastern Standard Time, Japanese government officials were ordering everyone within 12.5 miles of the plant to leave immediately, while those within 20 miles were ordered to stay indoors to reduce exposure to radiation. But many people are simply fleeing the area, according to news reports from the scene.
Low levels of radiation have been detected in Tokyo, 150 miles south of the plant, as well as at a U.S. military base south of Tokyo. Some 700 nuclear plant workers have been pulled from the site, although about 50 remained behind.
One possible, albeit worst-case scenario, would be a Three Mile Island-like disaster in which the fuel rods overheat, and turn partially or completely into a molten mass, but stay inside the containment structure.
If that happens, then it would take months if not years to clean up the site, but at least radiation would be contained.
Another worst-case scenario would be if the containment structure gives way due to overheating and a China Syndrome-like situation develops, with the radioactive molten mass sinking into the ground. In that case, it is possible that it could hit water in the ground and set off a steam explosion that could create a cloud containing radioactive elements.
In that case, it becomes important to know what kind of radiation is in the cloud.
Certain kinds, like radioactive iodine, have a half-life of just 7-8 days, Brown said, meaning anything released at the start of the crisis has already lost half of its radioactivity.
If the wind is blowing out to sea, that radioactive iodine will eventually dissipate. People can also take iodine pills to prevent the build-up of radioactive iodine in their thyroid glands, which can lead to cancer.
In the case of Chernobyl, Brown said, thousands of people were stricken with cancer because they were never told that the release of radiation infected the milk they were drinking.
"They didn't tell their own people there was an accident," he said. "It was as simple as: 'Don't drink the milk.' If they had acted proactively," fewer people would have gotten sick.
But other substances aside from radioactive iodine could be released that are more dangerous, such as cesium, which has a half-life of 30 years, Brown said.
"If that gets into environment, it lasts much longer," he said.
At that point, it also depends on how much cesium gets into the environment.
"It's all about the amounts," he said. "Because there's radiation in the environment wherever we go. You can measure it, so you know if it's a problem or not. ... It's all about magnitudes and pathways to people. It's not easy to get it out into the environment."
He added, "it could be transported out in steam or as a gas, or as particulates, in which case it could be a contamination issue."
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