Wednesday, March 16, 2011

Radiation exposure and the effects on human health

A look at what could happen to people who are exposed to radiation in the Japanese nuclear crisis.


As engineers have fought to avert a meltdown at the earthquake- and tsunami-crippled Fukushima No. 1 (Daiichi) power plant, nuclear authorities have reported that spikes of radiation have escaped from the facility at levels that can be dangerous to human health. Authorities have evacuated more than 170,000 people within 12 miles of the plant and have warned those within 20 miles to stay indoors and close off ventilation systems. They have also issued iodine tablets to those who have remained in the area and those at evacuation centers. At least 200 people have been exposed to radiation. Here's a look at the potential radiation exposures and effects on human health.

Is all radiation harmful?
No. There are two types of radiation: non-ionizing and ionizing. Non-ionizing radiation includes infrared radiation, radio waves, cellphone radiation and the radiation we use to cook food in a microwave. Such radiation does not break chemical bonds. If it is very intense, it can heat up tissues; otherwise, it does not have significant effects. It is not believed to cause cancer.
Ionizing radiation is much more dangerous because it does break chemical bonds and thus does cause cancer. Examples of this kind of radiation include X-rays, gamma rays and the alpha or beta particles emitted by radioactive elements as they decay.

What happens when someone is exposed to ionizing radiation?
That depends on how long you are exposed. The initial symptoms are identical to those suffered by a person undergoing radiation therapy for cancer. The first signs include nausea and fatigue, then vomiting. After that comes hair loss and diarrhea. For radiotherapy for tumors, the exposure generally stops after that point and the symptoms are controlled. But with heavier exposure, the next stage is generally destruction of the intestinal lining and worse diarrhea and dehydration, then central nervous system damage. After that comes loss of consciousness and, inevitably, death.

How does radiation released from nuclear plants compare with a nuclear bomb?
A nuclear explosion produces two types of radiation that has lethal effects. The blast itself produces X-rays and gamma rays that irradiate anyone near the site, usually with a lethal or near-lethal dose of radiation. Most of the 166,000 Japanese who died at Hiroshima in the first four months after the atomic bombing suffered from this type of radiation, which killed them directly or aggravated other injuries suffered in the blast.
It also produces clouds of radioactive ash that includes cesium-137, iodine-131, radioactive strontium and a host of other long-lived byproducts of the explosion — known collectively as fallout. This material can collect on skin and clothing, where it can emit radiation that pierces the skin. More important, it can accumulate in food, milk, water and other products that are ingested. It is not clear how many Hiroshima residents died of cancer from this source, but some estimates put it at more than 100,000.
Fukushima is not emitting gamma or X-irradiation. Most of the radioactivity is in the form of radiocesium and radioiodine, which are byproducts of the fission of uranium in the fuel rods.

What makes cesium-137 and iodine-131 dangerous?
Iodine-131 is absorbed preferentially in the thyroid gland, where it can cause tumors. It has a half-life of eight days and is most dangerous to children because it damages rapidly dividing cells. The problem can be substantially ameliorated by taking tablets of ordinary iodine, which bind to the thyroid and prevent the radioactive iodine from binding.

Cesium-137, which has a half-life of 30 years, is more serious. It is a salt that acts like potassium and goes everywhere in the body. It is absorbed into soft tissues, causing sarcomas. It contaminates food, water and milk and gets into the body when those things are ingested. Contamination with cesium-137 is one of the main reasons large areas of land had to be abandoned in the wake of the Chernobyl disaster in 1986.

How much exposure is enough to make someone sick?
The biological risk of exposure to radiation is measured in sieverts, or Sv. An exposure of 500,000 microsieverts, or µSv, can lead to nausea and fatigue within hours. A dose of 750,000 µSv causes hair loss within two or three weeks, and a dose of 1 million µSv will cause hemorrhage. Death usually occurs at a dose of 4 million µSv.
In terms of long-term effects, experts estimate that if 10,000 people were each exposed to 10,000 µSv of ionizing radiation in small doses over a lifetime, about five or six more people in the group would die of cancer than would be expected without the radiation exposure.
What were the health consequences of Chernobyl and Three Mile Island?
In the case of Chernobyl, United Nations reports have estimated that fewer than 50 people had died of causes directly related to radiation exposure. Most were rescue workers who had received high radiation doses; 28 died within the first few months. As many as 4,000 people are expected to eventually die of radiation-related causes. A 2005 report said about 4,000 thyroid cancers were directly related to radiation exposure, mostly in people who were children or adolescents at the time of the disaster and drank milk highly contaminated with radioactive iodine. At least nine died.

To track the health fallout of the 1979 Three Mile Island disaster, the Pennsylvania Department of Health kept a registry of more than 30,000 people who lived within five miles of the site at the time. Finding little evidence of significantly changed cancer rates, it discontinued the database in 1997.

So how much radiation have people in Japan been exposed to? How risky is it?
The levels of exposure are unclear. Radiation levels were reported to have jumped to about 400,000 µSv per hour inside the Fukushima plant after an explosion Tuesday, although the levels subsided rapidly. Sustained exposure to this level of radiation would be extremely hazardous. Levels outside the plant would have been substantially lower.

Civilians who have been exposed to radiation have been treated by simply getting their clothes washed and being given showers because the exposure has been so minimal.
Workers in the plant will receive the highest exposure, but they are outfitted with full protective gear, wear radiation badges and work for shifts of only an hour or two at a time. According to news reports, radiation levels in Tokyo have been 10 times normal, which is still very low.

Times staff writers Thomas H. Maugh II and Amina Khan contributed to this report.

Tuesday, March 15, 2011

Nuclear reactor explosion, not nuclear explosion

It is not skilful engineering or clever reactor design that precludes a nuclear explosion at a nuclear power plant, it is the laws of physics.

The materials in a nuclear reactor core and the uranium enrichment level make impossible a nuclear explosion of the type for which nuclear weapons are designed. Despite this, repeatedly we have heard talk of nuclear explosions in the media from observers, pundits, anti-nuclear activists and journalists.

An explosion at a nuclear reactor is not a nuclear explosion and can never be. Power plant grade uranium contains the fissile form of uranium, the uranium-235 isotope, at just a few percent, the majority is non-fissile U238. Compare that to weapons grade uranium which has to contain 80% or more of U235. Moreover, a nuclear weapon requires that a critical mass of the radioactive material be forced together quickly in a relatively small volume. This cannot happen in a nuclear plant, the low concentration of fissile U235 means it can never reach an explosively critical mass of fissile material but there is also no process that could force it together into a small volume quickly, anyway.

The same applies to the mixed oxide type reactor that use plutonium oxide and uranium oxide. It should be noted that plutonium is generated by the normal operation of a uranium-using power plant, although again it is the wrong ratio of isotopes for a nuclear weapon.

Essentially, the fuel concentration in a power plant is far too low to build the high-energy neutron stream needed to cause an explosive chain reaction. As to nucleear meltdown. The term nuclear meltdown is laden with China Syndrome style drama, but it does not lead to a nuclear explosion; a lot of heat is produced, and the nuclear fuel melts (happens at about 2700 Celsius). That’s it. Moreover, the melting process leads to less fissile material being in close contact when it spreads and melts through the floor of the reactor and the rock beneath. Incidentally, the hypothetical limit on depth the molten fuel could penetrate is about 15-20 metres, not the Earth’s core. Inevitably, the chain reaction that generates the heat slows of its own accord.

None of this is to say that what has happened in Japan is any less of a tragedy, it is just that phrases like nuclear meltdown and nuclear explosion used in this context in no way help, they spread fear, give tabloid headline writers scaremongering fodder, and are being hijacked repeatedly for personal agendas. Conventional explosions do occur, as we’ve learned this week from tragic events in Japan. But, these are not nuclear explosions. There is a risk of particles of radioactive material entering the atmosphere or the ocean, but this does not amount to the impact of an actual nuclear explosion.
New Scientist has a useful summary of what is happening at the Fukushima nuclear power plant in Japan following the Sendai earthquake and subsequent devastating tsunami.


Monday, March 14, 2011

Apple fans line up to buy first batch of iPad 2s

The updated version of Apple Inc.'s iPad tablet computer went on sale Friday afternoon, and was greeted by the now-familiar lines of buyers outside Apple stores.

The Cupertino company opened online sales of the iPad 2 at 4 a.m. local time, well before they became available in East Coast stores at 5 p.m. They were set to go on sale nationwide at the same hour, local time.
Apple fans, as usual, were eager to get their hands on the device as they waited at the company's Apple's Fifth Avenue store in New York. The line of customers, including some who traveled from Japan and Russia, snaked through the street-level plaza above the subterranean store while bystanders gawked at the crowd.
Employees cheered from inside the store as iPad buyers entered. Alex Shumilov, a customer who traveled from Moscow to snag two iPads, emerged first, beaming while holding one tablet in each hand. The trendy device won't go on sale outside the U.S. for another two weeks.

When the original version of the iPad debuted 11 months ago, Apple said it sold more than 300,000 in the first day. It ended up selling more than 15 million in the first nine months, including 7.3 million to holiday shoppers in the October-December quarter.

The new iPad model comes with several improvements over the original version but the same price tag - $499 to $829, depending on storage space and whether they can connect to the Internet over a cellular network. Analysts believe the improvement would make it more difficult for rivals to break Apple's hold on the emerging market for tablet computers.

The iPad 2 looks much like the first iPad, only with a sleeker, lighter body and a curved back. Among changes is the inclusion of cameras for videoconferencing, one on the front and one on the back.
With the original iPad, Apple proved there is a large market for a tablet that's less than a laptop and more than a smart phone, yet performs many of the same tasks. Competitors including Dell Inc. and Samsung Electronics Co. have been trying to lure consumers with smaller tablets, without much success. In February, Motorola Mobility Inc.'s Xoom went on sale with a new version of Google Inc.'s Android software designed especially for tablets.

Underscoring the importance of the iPad to the world's most valuable technology company, Apple CEO Steve Jobs emerged from a medical leave earlier this month to unveil the new version to bloggers and Apple enthusiasts. Jobs, 56, announced in January that he would take his third leave of absence in seven years to focus on his health. During that time, he has survived a rare but curable form of pancreatic cancer and undergone a liver transplant.

After its U.S. launch Friday, the iPad 2 goes on sale March 25 in 26 other markets, including Mexico, New Zealand, Spain and other European countries.

Refugees in Ishinomaki

Seeking Warmth: People who are isolated at an area in Ishinomaki, northern Japan sit around a fire and wait for rescue Sunday following Friday's massive earthquake and the ensuing tsunami. (AP Photo/Tokyo Shimbun, Koki Azechi)

Save Energy, Sony Turn off Final Fantasy Server

The earthquake and tsunami that struck Japan, making the Sony Online Entertainment decided to shut down the server MMO (Online Multiplayer Masive) for Final Fantasy XIV, Final Fantasy XI and PlayOnline service game for a while.

But Final Fantasy fans should not worry, because this service will return to normal. Sony's decision to disable its MMO server is the contribution the company is in Japan's recovery efforts after the earthquake and tsunami.

"Due to the earthquake which shook eastern Japan on March 11, 2011, the electric company in Japan called on all companies save as much energy to spare, anticipating a lack of supply of power,"wrote the Sony in his blog.

Sony suspend service for two MMO Final Fantasy and PlayOnline, began yesterday at three in the morning local time.

Not mentioned clearly, how long the server will be offline. However, Sony promised to update the additional information immediately after the server re-turned.

"Sony plans to make the server offline at least one week, but it could be much longer. There will be no charge to gamers for the server in offline state," added Sony.

Apart from two MMO Final Fantasy, other services that helped shut down a server offline for are:

Friend List Plus
FINAL FANTASY XI Linkshell Community Beta Version
PlayOnline Friend List Application
Community Site Registration Link: Owner Menu
PlayOnline Password Recovery
PlayOnline Account Cancellation
All activities requiring the confirmation of personal information

But their official website will remain online, as well as Final Fantasy XIV Lodestone site, forum games and support center official Square Enix, as the developer of Final Fantasy.

Japan, a country known for the advancement of this technology, also became the central gathering of world-class gaming company. Luckily, the most part, spared from severe damage caused by the earthquake and tsunami last Friday.

Based on reports from local media, gaming companies located in the vicinity of Tokyo such as Nintendo, Sega and Konami are not affected by the quake.

U.S. Parliament Urges Nuclear Termination

Nuclear emergencies that occur in Japan raises fears the United States. U.S. lawmakers called on the U.S. government to temporarily stop nuclear development in the country.

"I have been a loyal supporter of nuclear power because it is domesktik, ours and it's clean," said the influential Senator Joseph Lieberman told CBS television stations as reported by the AFP news agency on Monday (3/14/2011).

"Even so I think we should calmly and quickly to stop it until we can absorb what has happened in Japan as a result of the earthquake and tsunami," said Lieberman who became chairman of the Senate Homeland Security Committee U.S..

Appended Lieberman, the experts then have to see what else needed to be met from the power plants of new nuclear power we are building.

President Barack Obama wants to increase nuclear power as part of U.S. efforts to reduce country's dependence on foreign oil and coal.

The Obama administration has allocated U.S. $ 18.5 billion to spur the development of nuclear. A few months ago, a U.S. official revealed, his administration is committed to re-launch nuclear power industry as an important key to bringing the country into a clean energy economy.

Sunday, March 13, 2011

Facebook alternative Communications in Japan

Disruption of communication access via telephone in Japan made ​​it difficult finding information about family or friends in areas hit by disaster. There wits, residents there use up to stay connected.

As performed Duane Cavalier man from Detroit with the original Japanese wife, Maho Cavalier. They could finally find each other their respective news via Facebook.

Reported Windorstar and quoted on Sunday (03/13/2011), when an earthquake happens, Maho was in Tokyo while her husband Cavalier in Saitama, a region outside the capital of Japan.

Mentioned Maho, a large earthquake is indeed not to make Tokyo badly damaged. But all the facilities and infrastructure automatically die. Cell phone can not be used to communicate, as well as the office phone. Luckily, the Internet is still active and he also access up through his iPhone.

"When checking up Cavalier, apparently he did the same thing. My husband lived in Saitama all night," he said.

He mentioned, up to be the only way to communicate between them both and many other Japanese citizens who do the same. Besides Facebook, many are utilizing Twitter.

"It's the only way, then we continue to use it," he said.

Nuclear Radiation Victims in Japan Increased To 19 People

The number of people who tested positive for the nuclear radiation at the Fukushima nuclear power plants increased to 19 people. This number increased from 3 cases found on Saturday.

They are exposed to radiation at this time was taken to a nearby hospital. Thus was launched, Sunday (13/03/2011).

Fukushima nuclear power plant operator that is Tokyo Electric Power (TEPCO) nuclear safety agency has notified Japan that the radiation level at the Fukushima No. 1 nuclear reactor has exceeded the limit.

Radiation levels allowed is 500 micro Sievert. While radiation in Fukushima has reached 882 micro Sievert.

Fukushima nuclear power plant also states, reactor number 3 in the center of power it has lost the use of refrigeration. This is the sixth reactor at Fukushima No. 1 plant and the No. 2 who lost the use of cooling after a devastating earthquake and tsunami struck Japan on Friday.