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Japan's radioactive food and water problems widen
Parents in Tokyo were told today to avoid preparing infant formula milk in tap water following discovery of radioactive iodine-131 at levels twice the 100-becquerel limit set for babies.
Inspectors found levels of 210 becquerels per litre in tap water from the city's Kanamachi Purification Plant, which supplies the whole of Tokyo and five other major suburbs.
But officials have said that the advice is only precautionary, and babies won't be in any danger even if they have drunk the water.
According to the Japan Times, Kazuya Kumagai at the Japanese health ministry's Water Supply Division said:
The regulated level of 100 becquerels is a level that babies can tolerate for a long time without worrying about radiation
As residents stocked up on bottled water, chief cabinet secretary Yukio Edano sought to reassure adults that tap water remains safe enough to drink, wash and bathe in. No readings have yet breached the safe level set for adults, of 300 becquerels per litre.
Meanwhile, many media outlets report that certain vegetables are now off the menu in Fukushima, the prefecture where the stricken nuclear plant is based.
Earlier today, Fukushima governor Yuhei Sato told local people for the first time to avoid eating spinach, cabbage, broccoli, cauliflower and other locally-grown leafy vegetables. Shipments of contaminated spinach and other produce had been blocked earlier this week.
Some vegetables contained high amounts of radioactive caesium-137, an isotope that takes 30 years to decay to half the original amount, which could mean a prolonged ban on produce from some local farms.
In one vegetable, called kukitachina, radiation from caesium-137 reached 82,000 becquerels per kilogram, 164 times the corresponding safe limit of 500 becquerels. To provide reassurance, Edano said that even if someone ate this kukitachina for 10 consecutive days, the amount of radioactive material consumed would be half that to which people are exposed naturally in a whole year, and would pose no future health risks.
But the radiation levels do seem to be rising. Of 35 vegetables sampled, 25 contained caesium-137 above the limit and 21 had levels of iodine-131 above the safe level of 2000 becquerels per kilogram. Local levels of caesium-137 in soil are also rising, just as they did throughout Europe after the Chernobyl nuclear accident in 1986.
One sample from the village of Iatate, 40 kilometres from the stricken plant, contained 163,000 becquerels per kilogram of soil, 1630 times higher than background levels.
Yasuyuki Muramatsu of Gakushuin University, an expert on radiation in the environment, told NHK that because it is so long-lived, the radioactive caesium could affect agricultural activity for a long time.
Work to stabilise the stricken reactor itself continues, but was disrupted earlier today when black smoke began rising from reactor unit number 3. Radiation spiked briefly immediately after, then returned to previous levels an hour later after the smoke had cleared.
http://www.newscientist.com/blogs/shortsharpscience/2011/03/japans-radioactive-food-and-wa.html
For example, natural potassium (40K) in a typical human body produces 4,000 disintegrations per second, 4 kBq of activity.
Onyx8 wrote:You do know what a Becquerel is do you?
From Wiki:For example, natural potassium (40K) in a typical human body produces 4,000 disintegrations per second, 4 kBq of activity.
How do inspectors ensure the safety of older nuclear reactors?
Japanese regulators granted a 10-year extension to an aging reactor at the Fukushima Daiichi nuclear plant despite observing damaged components, according to a report in the New York Times. Inspectors spent just three days looking around, which is apparently very brief. What do inspectors look for in a graying reactor?
Rust, cracks, and pits, among other things. Nuclear reactors have thousands of parts—valves, pumps, pipes, turbines, etc. Inspectors monitor all these bits and pieces, but the greatest concerns in older plants are the reactor vessel, which houses the core, and the containment structure, which is the last line of defense between the fissioning uranium and the public. Radiation and ordinary weathering processes can undermine these components, so inspectors have to routinely measure the thickness of their walls and check for signs of corrosion or cracks in order to ensure that the barriers remain leak-proof.
Sixty years ago, when commercial nuclear reactors were in development, engineers couldn't say for sure how long a reactor vessel might last. Its 6- to 8-inch-thick steel walls are bombarded with radiation, and go through extreme heating and cooling cycles whenever the reactor is restarted—which happens every 18 or 24 months during the refueling process. (If one of those walls becomes brittle, it's necessary to shut down the reactor permanently, since replacing a reactor vessel requires dismantling half of the plant. Researchers are experimenting with technologies to repair damaged parts of the wall, but none of these methods has been deployed in a commercial reactor.)
To test the soundness of the vessels over time, nuclear engineers keep metal samples of the same type and thickness as the vessel wall itself inside the reactor during operation. They remove them periodically and examine them for wear. The assumption is that the samples are suffering the same effects as the reactor vessel. The current consensus is that, under normal operating conditions, a vessel can last for at least 60 years.
While early nuclear scientists were acutely concerned about the reactor vessel, most had confidence in the hardiness of the containment structures. After all, the thick metal and concrete walls outside the reactor are, in theory, insulated from the harsh conditions of a nuclear reactor. They are designed to withstand earthquakes and other acts of nature, and aren't exposed to a regular barrage of radiation. By the late 1980s, however, inspectors began to notice flaws. More than one-quarter of the containment systems at the 104 nuclear reactors operating in the United States have now shown some form of degradation, which can be caused by freeze-thaw cycles, erosion, and even plant matter growing through the concrete. Unlike reactor vessels, however, it's economically feasible to repair damaged containment structures.
There are several ways to monitor a containment structure. Inspectors conduct visual examinations, either with the naked eye or a magnifying glass, in search of rust or pitting. They can apply a liquid to the wall, wipe off surface fluid, and see if any managed to penetrate. Some engineers create a magnetic field in the wall, then spread a thin layer of iron particles. If the characteristic magnetic field pattern is disrupted, it suggests the presence of cracks. Sound waves, radiography, electrical resistance, and compression tests can also indicate flaws.
In the United States, the 1954 Atomic Energy Act (PDF) initially limited nuclear plant licenses to 40 years. As the first generation of nuclear reactors approached and surpassed the middle of their 40-year lifespan, the Nuclear Regulatory Commission published procedures in 1995 to offer license extensions. Today, most expiration dates have been put off by two decades, and there's talk of extending the limits up to 80 total years of operation. The possibility has split the scientific community, largely because of potentially undetectable effects of aging.
http://www.slate.com/id/2289016/
Fukushima radioactive fallout nears Chernobyl levels
Japan's damaged nuclear plant in Fukushima has been emitting radioactive iodine and caesium at levels approaching those seen in the aftermath of the Chernobyl accident in 1986. Austrian researchers have used a worldwide network of radiation detectors – designed to spot clandestine nuclear bomb tests – to show that iodine-131 is being released at daily levels 73 per cent of those seen after the 1986 disaster. The daily amount of caesium-137 released from Fukushima Daiichi is around 60 per cent of the amount released from Chernobyl.
The difference between this accident and Chernobyl, they say, is that at Chernobyl a huge fire released large amounts of many radioactive materials, including fuel particles, in smoke. At Fukushima Daiichi, only the volatile elements, such as iodine and caesium, are bubbling off the damaged fuel. But these substances could nevertheless pose a significant health risk outside the plant.
The organisation set up to verify the Comprehensive Nuclear-Test-Ban Treaty (CTBT) has a global network of air samplers that monitor and trace the origin of around a dozen radionuclides, the radioactive elements released by atomic bomb blasts – and nuclear accidents. These measurements can be combined with wind observations to track where the radionuclides come from, and how much was released.
The level of radionuclides leaking from Fukushima Daiichi has been unclear, but the CTBT air samplers can shed some light, says Gerhard Wotawa of Austria's Central Institute for Meteorology and Geodynamics in Vienna.
Ill wind
For the first two days after the accident, the wind blew east from Fukushima towards monitoring stations on the US west coast; on the third day it blew south-west over the Japanese monitoring station at Takasaki, then swung east again. Each day, readings for iodine-131 at Sacramento in California, or at Takasaki, both suggested the same amount of iodine was coming out of Fukushima, says Wotawa: 1.2 to 1.3 × 1017 becquerels per day.
The agreement between the two "makes us confident that this is accurate", he says. So do similar readings at CTBT stations in Alaska, Hawaii and Montreal, Canada – readings at the latter, at least, show that the emissions have continued.
In the 10 days it burned, Chernobyl put out 1.76 × 1018 becquerels of iodine-131, which amounts to only 50 per cent more per day than has been calculated for Fukushima Daiichi. It is not yet clear how long emissions from the Japanese plant will continue.
Similarly, says Wotawa, caesium-137 emissions are on the same order of magnitude as at Chernobyl. The Sacramento readings suggest it has emitted 5 × 1015 becquerels of caesium-137 per day; Chernobyl put out 8.5 × 1016 in total – around 70 per cent more per day.
"This is not surprising," says Wotawa. "When the fuel is damaged there is no reason for the volatile elements not to escape," and the measured caesium and iodine are in the right ratios for the fuel used by the Fukushima Daiichi reactors. Also, the Fukushima plant has around 1760 tonnes of fresh and used nuclear fuel on site, and an unknown amount has been damaged. The Chernobyl reactor had only 180 tonnes.
The amounts being released, he says, are "entirely consistent" with the relatively low amounts of caesium and iodine being measured in soil, plants and water in Japan, because so much has blown out to sea. The amounts crossing the Pacific to places like Sacramento are vanishingly small – they were detected there because the CTBT network is designed to sniff out the tiniest traces.
Dangerous isotopes
The Chernobyl accident emitted much more radioactivity and a wider diversity of radioactive elements than Fukushima Daiichi has so far, but it was iodine and caesium that caused most of the health risk – especially outside the immediate area of the Chernobyl plant, says Malcolm Crick, secretary of a United Nations body that has just reviewed the health effects of Chernobyl. Unlike other elements, he says, they were carried far and wide by the wind...cont.
http://www.newscientist.com/article/dn20285-fukushima-radioactive-fallout-nears-chernobyl-levels.html
cherries wrote:thanks for the infoHow do inspectors ensure the safety of older nuclear reactors?
Japanese regulators granted a 10-year extension to an aging reactor at the Fukushima Daiichi nuclear plant despite observing damaged components, according to a report in the New York Times. Inspectors spent just three days looking around, which is apparently very brief. What do inspectors look for in a graying reactor?
Rust, cracks, and pits, among other things. Nuclear reactors have thousands of parts—valves, pumps, pipes, turbines, etc. Inspectors monitor all these bits and pieces, but the greatest concerns in older plants are the reactor vessel, which houses the core, and the containment structure, which is the last line of defense between the fissioning uranium and the public. Radiation and ordinary weathering processes can undermine these components, so inspectors have to routinely measure the thickness of their walls and check for signs of corrosion or cracks in order to ensure that the barriers remain leak-proof.
Sixty years ago, when commercial nuclear reactors were in development, engineers couldn't say for sure how long a reactor vessel might last. Its 6- to 8-inch-thick steel walls are bombarded with radiation, and go through extreme heating and cooling cycles whenever the reactor is restarted—which happens every 18 or 24 months during the refueling process. (If one of those walls becomes brittle, it's necessary to shut down the reactor permanently, since replacing a reactor vessel requires dismantling half of the plant. Researchers are experimenting with technologies to repair damaged parts of the wall, but none of these methods has been deployed in a commercial reactor.)
To test the soundness of the vessels over time, nuclear engineers keep metal samples of the same type and thickness as the vessel wall itself inside the reactor during operation. They remove them periodically and examine them for wear. The assumption is that the samples are suffering the same effects as the reactor vessel. The current consensus is that, under normal operating conditions, a vessel can last for at least 60 years.
While early nuclear scientists were acutely concerned about the reactor vessel, most had confidence in the hardiness of the containment structures. After all, the thick metal and concrete walls outside the reactor are, in theory, insulated from the harsh conditions of a nuclear reactor. They are designed to withstand earthquakes and other acts of nature, and aren't exposed to a regular barrage of radiation. By the late 1980s, however, inspectors began to notice flaws. More than one-quarter of the containment systems at the 104 nuclear reactors operating in the United States have now shown some form of degradation, which can be caused by freeze-thaw cycles, erosion, and even plant matter growing through the concrete. Unlike reactor vessels, however, it's economically feasible to repair damaged containment structures.
There are several ways to monitor a containment structure. Inspectors conduct visual examinations, either with the naked eye or a magnifying glass, in search of rust or pitting. They can apply a liquid to the wall, wipe off surface fluid, and see if any managed to penetrate. Some engineers create a magnetic field in the wall, then spread a thin layer of iron particles. If the characteristic magnetic field pattern is disrupted, it suggests the presence of cracks. Sound waves, radiography, electrical resistance, and compression tests can also indicate flaws.
In the United States, the 1954 Atomic Energy Act (PDF) initially limited nuclear plant licenses to 40 years. As the first generation of nuclear reactors approached and surpassed the middle of their 40-year lifespan, the Nuclear Regulatory Commission published procedures in 1995 to offer license extensions. Today, most expiration dates have been put off by two decades, and there's talk of extending the limits up to 80 total years of operation. The possibility has split the scientific community, largely because of potentially undetectable effects of aging.
http://www.slate.com/id/2289016/
cherries wrote:Fukushima radioactive fallout nears Chernobyl levels
Japan's damaged nuclear plant in Fukushima has been emitting radioactive iodine and caesium at levels approaching those seen in the aftermath of the Chernobyl accident in 1986. Austrian researchers have used a worldwide network of radiation detectors – designed to spot clandestine nuclear bomb tests – to show that iodine-131 is being released at daily levels 73 per cent of those seen after the 1986 disaster. The daily amount of caesium-137 released from Fukushima Daiichi is around 60 per cent of the amount released from Chernobyl.
The difference between this accident and Chernobyl, they say, is that at Chernobyl a huge fire released large amounts of many radioactive materials, including fuel particles, in smoke. At Fukushima Daiichi, only the volatile elements, such as iodine and caesium, are bubbling off the damaged fuel. But these substances could nevertheless pose a significant health risk outside the plant.
The organisation set up to verify the Comprehensive Nuclear-Test-Ban Treaty (CTBT) has a global network of air samplers that monitor and trace the origin of around a dozen radionuclides, the radioactive elements released by atomic bomb blasts – and nuclear accidents. These measurements can be combined with wind observations to track where the radionuclides come from, and how much was released.
The level of radionuclides leaking from Fukushima Daiichi has been unclear, but the CTBT air samplers can shed some light, says Gerhard Wotawa of Austria's Central Institute for Meteorology and Geodynamics in Vienna.
Ill wind
For the first two days after the accident, the wind blew east from Fukushima towards monitoring stations on the US west coast; on the third day it blew south-west over the Japanese monitoring station at Takasaki, then swung east again. Each day, readings for iodine-131 at Sacramento in California, or at Takasaki, both suggested the same amount of iodine was coming out of Fukushima, says Wotawa: 1.2 to 1.3 × 1017 becquerels per day.
The agreement between the two "makes us confident that this is accurate", he says. So do similar readings at CTBT stations in Alaska, Hawaii and Montreal, Canada – readings at the latter, at least, show that the emissions have continued.
In the 10 days it burned, Chernobyl put out 1.76 × 1018 becquerels of iodine-131, which amounts to only 50 per cent more per day than has been calculated for Fukushima Daiichi. It is not yet clear how long emissions from the Japanese plant will continue.
Similarly, says Wotawa, caesium-137 emissions are on the same order of magnitude as at Chernobyl. The Sacramento readings suggest it has emitted 5 × 1015 becquerels of caesium-137 per day; Chernobyl put out 8.5 × 1016 in total – around 70 per cent more per day.
"This is not surprising," says Wotawa. "When the fuel is damaged there is no reason for the volatile elements not to escape," and the measured caesium and iodine are in the right ratios for the fuel used by the Fukushima Daiichi reactors. Also, the Fukushima plant has around 1760 tonnes of fresh and used nuclear fuel on site, and an unknown amount has been damaged. The Chernobyl reactor had only 180 tonnes.
The amounts being released, he says, are "entirely consistent" with the relatively low amounts of caesium and iodine being measured in soil, plants and water in Japan, because so much has blown out to sea. The amounts crossing the Pacific to places like Sacramento are vanishingly small – they were detected there because the CTBT network is designed to sniff out the tiniest traces.
Dangerous isotopes
The Chernobyl accident emitted much more radioactivity and a wider diversity of radioactive elements than Fukushima Daiichi has so far, but it was iodine and caesium that caused most of the health risk – especially outside the immediate area of the Chernobyl plant, says Malcolm Crick, secretary of a United Nations body that has just reviewed the health effects of Chernobyl. Unlike other elements, he says, they were carried far and wide by the wind...cont.
http://www.newscientist.com/article/dn20285-fukushima-radioactive-fallout-nears-chernobyl-levels.html
Onyx8 wrote:OK, So engineers have found out that reactors were safer than they first thought and your point is?
Onyx8 wrote:
It would seem that the point you made by posting the article is that reactors are safer than they were thought to be when originally built. That is what the article says, if you're ok with that then great.
The possibility has split the scientific community, largely because of potentially undetectable effects of aging.
Onyx8 wrote:What's ironic is the people who fled Tokyo to avoid radiation actually exposed themselves to higher doses of radiation in the aircraft in which they escaped than they would have received by staying put. The fear caused them more irradiation than the reality.
source and more including:A MEDICAL PROBLEM OF VAST DIMENSIONS: Dr Helen Caldicott 25 March, 2011
As I write this on 25 March from Ottawa , two weeks since the earthquake and tsunami and the calamity that has befallen the Fukashima Nuclear Plant No 1, the situation has grown increasingly grave. Despite the heroic efforts of the “Nuclear Samurai” – the TEPCO employees who have selflessly and heroically fought to
stabilize the reactors and restore power – there are worrying signs that signal dangerous instability continues to reign. Among them, the announcement today that one of the reactor cores may have suffered a break that could have released large amounts of radiation at the plant; the widening of the exclusion zone to 30 kilometers ; and the US government ban on certain milk and vegetables from that area from importation.
In truth, as I say in this just-published CNN Opinion piece nuclear power and its deleterious effects are a medical problem of vast dimensions -- the greatest public health hazard the world will ever see.
Tragically, the “Nuclear Samurai” work for a company -- TEPCO --that has been exposed as having ignored mandatory safety checks at Fukushima ; as allowing spent fuel rods far in excess of the number that was deemed prudent to be stored on site; and as being evasive and unforthcoming about the real facts of the unfolding emergency
What we have also seen is a second tsunami of a different kind – a tidal wave of blow-back from the nuclear industry around the world, which has been rocked back on its heels by Fukushima but is now regrouping. There are claims that radiation is good for you; that nuclear power is still the only answer to global warming; and that fears about the safety of nuclear power are unwarranted and panic-stricken.
Let us be clear: there are billions and billions of dollars at stake for the nuclear industry, which has, as I’ve written earlier, managed to bamboozle governments around the world , much of the press, and many ordinary citizens into believing that nuclear power is green and clean. Nothing could be further from the truth. The industry will not walk away from that money without a fight.
Nuclear Re-Think
by Patrick Moore
PDF AR CH EN FR RUS SP
Patrick Moore, avid environmentalist and co-founder of Greenpeace, makes the
case for nuclear energy.
In the early 1970s when I helped found Greenpeace, I believed that nuclear energy was synonymous with nuclear holocaust, as did most of my compatriots. That conviction inspired Green-peace’s first voyage up the spectacular rocky northwest coast to protest the testing of US hydrogen bombs in Alaska’s Aleutian Islands.
Thirty years on, my views have changed, and the rest of the environmental movement needs to update its views, too, because nuclear energy is the only non-greenhouse-gas-emitting power source that can effectively replace fossil fuels while satisfying the world’s increasing demand for energy.
Today, 441 nuclear plants operating globally avoid the release of nearly 3 billion tonnes of CO2 emissions annually—the equivalent of the exhaust from more than 428 million cars.
My views have changed because nuclear energy is the only non-greenhouse-gas-emitting power source that can effectively replace fossil fuels while satisfying the world’s increasing demand for energy. —Patrick Moore
To reduce substantially our dependence on fossils fuels, we must work together to develop a global nuclear energy infrastructure. Nuclear energy is clean, cost-effective, reliable and safe.
In 1979 Jane Fonda and Jack Lemmon both won Oscars for their starring roles in “The China Syndrome.” In the film, a nuclear reactor meltdown threatened the survival of an entire city.
Twelve days after the blockbuster film opened, a reactor core meltdown at ThreeMile Island sent shivers of fear through the country.
At the time no one noticed Three Mile Island was a success story. The concrete containment structure did as it was designed to do: it prevented radiation from escaping into the environment. While the reactor was crippled, there was no injury or death among the public or nuclear workers.
This was the only serious accident in the history of nuclear energy generation in the United States. There hasn’t been a nuclear plant built since.
In the USA today, there are 103 nuclear reactors quietly delivering 20% of America’s electricity. About 80% of the people living within 10 miles of these plants approve of them. That high approval rating doesn’t include the plant workers who have a direct personal interest in supporting their safe, well-paying jobs. Although I don’t live near a nuclear plant, I am now squarely in their camp.
I am not alone among seasoned environmental activists and thinkers in changing my mind on the subject. James Lovelock, father of the Gaia theory and leading atmospheric scientist, believes nuclear energy is the only way to avoid catastrophic climate change.
Stewart Brand, founder of the Whole Earth Catalogue and holistic ecology thinker, says the environmental movement must embrace nuclear energy to reduce its dependence on fossil fuels. The late Bishop Hugh Montefiore, founder and director of Friends
of the Earth UK, was forced to resign when he penned a pro-nuclear article in a church newsletter. Such opinions have been met with inquisition-like excommunication from the anti-nuclear priesthood.
Below is a very brief summary of some key events of the last few days, since the previous status report:
1. There has been concern about salt accumulation in reactor vessels 1-3 (as steam evaporates the injected sea water, the salt is left behind, and if concentrations build to beyond the saturation point, it will begin to deposit and potentially insulate the fuel assemblies). However, NEI now reports the following welcome news:
Fresh water is being injected into the reactor pressure vessel at reactor 3 at Fukushima Daiichi nuclear power plant, Japan’s Nuclear and Industrial Safety Agency said.
TEPCO said that radioactive materials discovered at the reactor 3 turbine building possibly came from water from the reactor system, not the spent fuel pool. TEPCO made that statement after collecting samples of contaminated water in the reactor 3 turbine building and conducting a gamma-emitting nuclide analysis of the sample. The reactor pressure and drywell pressure at reactor 3 remained stable on Friday, leading TEPCO to believe that “the reactor pressure vessel is not seriously damaged.
Cooling efforts at Reactor 1 already had switched back to fresh water cooling. Reactor 2 is still being injected with seawater, but is expected to switch to fresh water soon.
The temperature at the bottom head of the reactor pressure vessels are now 149 C (unit 1), 104 C (unit 2) and 111 C (unit 3) — detailed data in reports below.
2. TEPCO Workers laying cables in the turbine hall of unit 3 stood in ankle-deep stagnant water and their feet were irradiated with beta rays (~180 mSv dose), with shallow burns, after ignoring their dosiometer warnings. They have since been hospitalised. Details in the reports below. 17 personnel have now received doses of >100 mSv, but none >250 mSv — the dose allowed by authorities in the current situation.
3. Water spraying continues on spent fuel ponds 2, 3 and 4, to ensure the uranium fuel rods remain covered. The temperature in unit 2 pool was recently measured at 52 C (see detailed data below).
4. On radiation: levels around the plant perimeter are relatively low and steadily decreasing. Levels of I-131 in drinking water supplies in Tokyo are now below regulated limits and restrictions have been lifted. The IAEA radiation monitoring data, at a distance of 34 to 62 km from Fukushima Daiichi, showed very low levels. To quote:
On 25th March, the IAEA radiation monitoring team made additional measurements at distances from 34 to 62 km from the Fukushima nuclear power plant. At these locations, the dose rate ranged from 0.73 to 8.8 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.07 to 0.96 Megabecquerel per square metre.
5. World Nuclear News provides a new summary: Fukushima Daiichi two weeks on. To quote:
Investigations are now underway into the unexpectedly high level of contamination in the water, particularly as the basement of the turbine building is not a recognised radiation area. One theory is that there is a leak from the reactor circuit, but pressures in the reactor vessel indicate this must be elsewhere in the loop.
Despite this disappointment, steady progress continues to be made on site. Instrumentation is being recovered at units 1, 2 and 4 and lights are on in the control rooms of units 1 and 3. Power connections have reached all the units and checks are underway before normal systems can be re-energised. The shared pond for used fuel pond has now been reconnected.
more
http://bravenewclimate.com/2011/03/26/f ... #more-4277
http://bravenewclimate.com/
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