From Bloomberg News – May 19, 2011

By Yuji Okada, Tsuyoshi Inajima and Shunichi Ozasa

A radiation alarm went off at Tokyo Electric Power Co.’s Fukushima nuclear power plant before the tsunami hit on March 11, suggesting that contrary to earlier assumptions the reactors were damaged by the earthquake that spawned the wall of water.

A monitoring post on the perimeter of the plant about 1.5 kilometers (1 mile) from the No. 1 reactor went off at 3:29 p.m., minutes before the station was overwhelmed by the tsunami that knocked out backup power that kept reactor cooling systems running, according to documents supplied by the company. The monitor was set to go off at high levels of radiation, an official said.

“We are still investigating whether the monitoring post was working properly,” said Teruaki Kobayashi, the company’s head of nuclear facility management. “There is a possibility that radiation leaked before the tsunami arrived.” Kobayashi said he didn’t have the exact radiation reading that would trigger the sensor.

Officials at the company, known as Tepco, had earlier said the plant stood up to the magnitude-9 quake and was crippled by the tsunami that followed, causing the world’s worst nuclear crisis since Chernobyl in 1986. The early radiation alarm has implications for other reactors in Japan, one of the most earthquake prone countries in the world, because safety upgrades ordered by the government since March 11 have focused on the threat from tsunamis.

Earthquake Risk

Many scientists have considered the possibility of damage to Fukushima reactors from the quake, said Tetsuo Ito, head of the Atomic Energy Research Institute at Kinki University in western Japan. “Utilities should reinforce safety measures at nuclear power plants, particularly ones housing old reactors like the Fukushima station.”

The company’s shares fell 8 percent today to 358 yen. They’ve fallen 83 percent since the disaster. The cost of protecting the Tepco’s debt from default rose to a record today, according to data provider CMA.

Tepco this week released thousands of pages of documents that highlight the chaos in the early hours of the disaster as workers frantically tried to prevent meltdowns in three of six reactors at Fukushima. They included pictures of whiteboards with scribbled notes of times and events.

Among the documents, the pressure and water level inside of No. 1 reactor inner vessel fluctuated after the earthquake hit at 2:46 p.m. Most of the readings for the No. 1 reactor go blank a little after 3:30 p.m. when the waves swamped the plant.

Venting Attempts

The company is still verifying the accuracy of the data, Takeo Iwamoto, a spokesman for the utility, said. Tepco submitted the documents to the Nuclear and Industrial Safety Agency on May 16 after the watchdog requested them, Iwamoto said. The files were released to the media to increase transparency, he said.

The documents show that a little after 9 a.m. on March 12, workers at the No. 1 reactor started trying to vent steam and gas as pressure in the reactor exceeded design specifications. The vent was partly opened manually at about 9:15 a.m. and attempts to get it fully opened were abandoned about 15 minutes later due to high radiation levels.

Workers in the control room then opened it by remote control, only for it to keep closing, according to the documents. A build up of hydrogen gas in the reactor building then caused an explosion that blew out part of the structure at 3:36 p.m. the same day.

Attempts to vent gas at the No. 2 and No. 3 reactors probably also failed and the pressure inside exceeded design levels for their containment vessels, the records show. Gauges in these buildings, which later were damaged by hydrogen explosions, also failed.

Instrument Blindness

Reading radiation and pressure levels was the only way to establish whether venting succeeded, Kobayashi said.

On May 15, or more than two months after the disaster at the Fukushima Dai-Ichi plant, Tepco said conditions were worse than expected in reactor No. 1 when it found all uranium fuel rods had melted.

Two workers entered the Fukushima the No. 3 reactor building to check radiation levels yesterday, the first time they’ve been in since March 14, spokesman Takeo Iwamoto said by telephone.

Yesterday it sent four workers into reactor No. 2 for the first time since March 14 to measure radiation levels and assess whether work can be done to fix gauges that will show the condition of the core.

Beside radiation leaks into the atmosphere forcing about 50,000 families near the plant to evacuate, more than 10 million liters (2.6 million gallons) of radiation-contaminated water have leaked or been released into the sea.

Millions of liters of radiated water have also filled basements and trenches at the station from leaking reactor vessels and piping.

Japan’s government in April raised the severity rating of the Fukushima crisis to the highest on an international scale, the same level as the Chernobyl disaster. The station, which has experienced hundreds of aftershocks since March 11, may release more radiation than Chernobyl before the crisis is contained, Tepco officials have said.

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From Time Magazine’s Ecocentric Blog – May 16, 2011

by Eben Harrell

The China Syndrome refers to a scenario in which a molten nuclear
reactor core could could fission its way through its containment vessel,
melt through the basement of the power plant and down into the earth.
While a molten reactor core wouldn’t burn “all the way through to China”
it could enter the soil and water table and cause huge contamination in
the crops and drinking water around the power plant. It’s a nightmare
scenario,the stuff of movies. And it might just have happened at Fukushima.

Last week, plant operator Tepco sent engineers in to recalibrate
water level gauges in reactor number 1. They made an alarming discovery:
virtually all the fuel in the core had melted down. That means that the
zirconium alloy tubes that hold the uranium fuel and the fuel itself
lies in a clump—either at the bottom of the pressure vessel, or in the
basement below or possibly even outside the containment building.
Engineers don’t know for sure, though current temperature readings
suggest that fission inside the reactor core has definitely ceased for
good (i.e. there will be no further melting).

Anecdotal evidence doesn’t bode well for how far the fuel melted:
Tepco has been pumping thousands of tons of water onto reactor 1 to try
to cool it—yet the water level in the containment vessel is too low to
run an emergency cooling system. That means the water is escaping
somewhere on a course cut by molten fuel–probably into the basement of
the reactor building, though it’s also possible it melted through
everything into the earth.

Many experts say a full-blown China syndrome is unlikely in large
part because the fuel from the type of reactors at Fukushima is designed
in such a way that it probably won’t sustain “recriticality” once
meltdown occurs. What’s more,  boron, which slows nuclear reactions, was
pumped into the cooling water of the reactor after the initial accident
to prevent the core from going “critical” again.

But assuming a worst case scenario hasn’t occurred, having so much
highly radioactive water sloshing around the basement is going to make
cleanup even more difficult. Tepco says it will come up with a new plan
to stabilize the reactor by Tuesday—and their main task will be to find a
way to suck up the water and store it while simultaneously ensuring the
reactor core remains cool. It’s unclear how this will be achieved, but
according to press reports, a giant water-storage barge – a Megafloat –
has been dispatched to Fukushima as a possible storage site for
contaminated water, and will arrive at the end of the month.

Tepco also said that it has started preparatory work for the
construction of a cover for unit 1’s reactor building, which had its
roof blown off by a hydrogen explosion on March 12.  The cover is to be
built as a temporary measure to prevent the release of radioactive
substances until further measures can be put in place, Nature News reported.

Meanwhile, around 5,000 residents in two towns, Kawamata and Iitate,
some 30 km from the power plant—well beyond the the 20 km exclusion
zone–were evacuated on Monday. More evacuations are expected in the
coming days as Tepco continues to struggle with the crisis. Around 
3,400 cows, 31,500 pigs and 630,000 chickens will soon be slaughtered
inside the Fukushima exclusion zone as feeding them has proven to be
impossible.

It’s difficult to say for sure just how bad things are at the plant
itself—high radioactive levels mean that engineers can’t get close to
the reactor cores themselves and can only make inferences, deductions
and guesses about the extent of the damage. As Alexis Madrigal of the Atlantic has
pointed out, we’ve faced this uncertainty—and troubling surprises—
before. Eight months after the Three Mile Island accident, “an Oak Ridge
National Laboratory scientist declared, ‘Little, if any, fuel melting
occurred, even though the reactor core was uncovered. The safety systems
functioned reliably.’ A few years later, robotic sorties into the area
revealed that half the core — not ‘little, if any’ — had melted down.”

I and TIME’s Kiev-based stringer recently published a piece for TIME from
Chernobyl in Ukraine, where clean-up efforts continue a full 25 years
after the accident. Whatever the end game at Fukushima, get your head
around this, folks: it is going to be a huge mess for a long time yet.

From the Vancouver Sun – May 13, 2011

by Julian Ryall, Daily Telegraph

One of the reactors at the crippled Fukushima Daiichi power plant did
sustain a nuclear meltdown, Japanese officials admitted for the first
time on Thursday, describing finding a pool of molten fuel at the bottom
of the reactor’s containment vessel.

Engineers from the Tokyo
Electric Power company (Tepco) entered the No. 1 reactor at the end of
last week for the first time since the March 11 tsunami and saw the top
1.5 metres or so of the core’s threemetre-long fuel rods had been
exposed to the air and melted down.

Previously, Tepco believed
that the core of the reactor was submerged in enough water to keep it
stable and that only 55 per cent of the core had been damaged. Now, the
company is worried that the molten pool of radioactive fuel may have
burned a hole through the bottom of the containment vessel, causing a
leak of highly radioactive water.

“We will have to revise our
plans,” said Junichi Matsumoto, a spokesman for Tepco. “We cannot deny
the possibility that a hole in the pressure vessel caused water to
leak.” Tepco has not clarified what other barriers there are to stop
radioactive fuel leaking if the steel containment vessel has been
breached. Greenpeace said the situation could escalate rapidly if “the
lava melts through the vessel.”

However, an initial plan to flood
the entire reactor core with water to keep its temperature from rising
has now been abandoned because it might exacerbate the leak.

Tepco
said there was enough water at the bottom of the vessel to keep both
the puddle of melted fuel and the remaining fuel rods cool. The company
added that it had sealed a leak of radioactive water from the No. 3
reactor after water was reportedly discovered to be flowing into the
ocean. A similar leak had discharged radioactive water into the sea in
April from the No. 2 reactor.

Greenpeace said significant amounts
of radioactive material had been released into the sea and that samples
of seaweed taken from as far as 60 km from the Fukushima plant had been
found to contain radiation well above legal limits. Of the 22 samples
tested, 10 were contaminated with five times the legal limit of iodine
131 and 20 times of cesium 137.

Seaweed is a huge part of the
Japanese diet and the average household eats almost three kilograms a
year. Fishermen are preparing to start this season’s harvest on May 20.
Inland from the plant, there has been a cull of livestock left inside
the 30-km mandatory exclusion zone with thousands of cows, horses and
pigs destroyed, including 260,000 chickens from the town of Minamisoma.

Fromt he Prince George Citizen – April 18, 2011

by Arthur Williams

Two B.C. organizations are calling for increased radiation testing, following the discovery of increased radiation levels

Testing done by Natural Resources
Canada and Health Canada showed slightly elevated levels of radiation in
March and April, following the disaster at the Fukushima reactor in
Japan following a massive earthquake and tsunami.

Better Radiation Testing B.C. and the
B.C. Environmental Network are calling for increased screening to ensure
British Columbians, particularly northern British Columbians, are safe.

“There is no monitoring in the northern
part of B.C. -and why?” Better Radiation Testing B.C. committee member
Rita Dawson said. “We’re concerned about the entire province, not just
the Lower Mainland and the island.”

Health Canada has conducted regular
testing in Vancouver, Victoria, Naniamo and Sydney since March. Natural
Resources Canada conducted a single test on Haida Gwaii on March 24,
which showed a radiation level of 0.73 microsieverts per day.

The average daily expose in Vancouver
in 2010 was 0.44 microsieverts. However, the average daily radiation
exposure in Halifax in 2010 was 0.80 microsieverts per day.

Fellow committee member Daniel Rubin said increased monitoring needs to be done of rainwater and at B.C.’s ports.

“I know they are testing port
facilities in Vancouver. I’m not certain… if they have the same kind
of quick scan in Prince Rupert,” he said. “The Chinese have already
refused a cargo ship already, so this is an issue. After Chernobyl they
found the major vector for radiation was their transportation system.”

The groups are calling for increased
testing of air samples across B.C., regular testing of drinking water,
spot checks of dairy products, seafood and leafy vegetables, and
increased disclosure of test results.

Researchers at the University of Southern California found rain with 181 times the normal level of radioactivity, he said.

“I’m not saying the sky is falling,”
Rubin said. “But this stuff is invisible, it’s tasteless and odourless.
The onus is on the government to do a minimum amount of spot checking
-just in case.”

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From the Daily Telegraph – April 17, 2011

by Ambrose Evans-Pritchard

A few weeks before the tsunami struck Fukushima’s uranium reactors and
shattered public faith in nuclear power, China revealed that it was
launching a rival technology to build a safer, cleaner, and ultimately
cheaper network of reactors based on thorium.

“If it begins to overheat, a little plug melts and the salts drain into a pan.
There is no need for computers, or the sort of electrical pumps that were
crippled by the tsunami. The reactor saves itself,” he said.

“They operate at atmospheric pressure so you don’t have the sort of hydrogen
explosions we’ve seen in Japan. One of these reactors would have come
through the tsunami just fine. There would have been no radiation release.”

Thorium is a silvery metal named after the Norse god of thunder. The metal has
its own “issues” but no thorium reactor could easily spin out of control in
the manner of Three Mile Island, Chernobyl, or now Fukushima.

Professor Robert Cywinksi from Huddersfield University said thorium must be
bombarded with neutrons to drive the fission process. “There is no chain
reaction. Fission dies the moment you switch off the photon beam. There are
not enough neutrons for it continue of its own accord,” he said.

Dr Cywinski, who anchors a UK-wide thorium team, said the residual heat left
behind in a crisis would be “orders of magnitude less” than in a uranium
reactor.

The earth’s crust holds 80 years of uranium at expected usage rates, he said.
Thorium is as common as lead. America has buried tons as a by-product of
rare earth metals mining. Norway has so much that Oslo is planning a
post-oil era where thorium might drive the country’s next great phase of
wealth. Even Britain has seams in Wales and in the granite cliffs of
Cornwall. Almost all the mineral is usable as fuel, compared to 0.7pc of
uranium. There is enough to power civilization for thousands of years.

I write before knowing the outcome of the Fukushima drama, but as yet none of
15,000 deaths are linked to nuclear failure. Indeed, there has never been a
verified death from nuclear power in the West in half a century. Perspective
is in order.

We cannot avoid the fact that two to three billion extra people now expect –
and will obtain – a western lifestyle. China alone plans to produce 100m
cars and buses every year by 2020.

The International Atomic Energy Agency said the world currently has 442
nuclear reactors. They generate 372 gigawatts of power, providing 14pc of
global electricity. Nuclear output must double over twenty years just to
keep pace with the rise of the China and India.

If a string of countries cancel or cut back future reactors, let alone follow
Germany’s Angela Merkel in shutting some down, they shift the strain onto
gas, oil, and coal. Since the West is also cutting solar subsidies, they can
hardly expect the solar industry to plug the gap.

BP’s disaster at Macondo should teach us not to expect too much from oil
reserves deep below the oceans, beneath layers of blinding salt. Meanwhile,
we rely uneasily on Wahabi repression to crush dissent in the Gulf and keep
Arabian crude flowing our way. So where can we turn, unless we revert to
coal and give up on the ice caps altogether? That would be courting fate.

US physicists in the late 1940s explored thorium fuel for power. It has a
higher neutron yield than uranium, a better fission rating, longer fuel
cycles, and does not require the extra cost of isotope separation.

The plans were shelved because thorium does not produce plutonium for bombs.
As a happy bonus, it can burn up plutonium and toxic waste from old
reactors, reducing radio-toxicity and acting as an eco-cleaner.

Dr Cywinski is developing an accelerator driven sub-critical reactor for
thorium, a cutting-edge project worldwide. It needs to £300m of public money
for the next phase, and £1.5bn of commercial investment to produce the first
working plant. Thereafter, economies of scale kick in fast. The idea is to
make pint-size 600MW reactors.

Yet any hope of state support seems to have died with the Coalition budget
cuts, and with it hopes that Britain could take a lead in the energy
revolution. It is understandable, of course. Funds are scarce. The UK has
already put its efforts into the next generation of uranium reactors. Yet
critics say vested interests with sunk costs in uranium technology succeeded
in chilling enthusiasm.

The same happened a decade ago to a parallel project by Nobel laureate Carlo
Rubbia at CERN (European Organization for Nuclear Research). France’s
nuclear industry killed proposals for funding from Brussels, though a French
group is now working on thorium in Grenoble.

Norway’s Aker Solution has bought Professor Rubbia’s patent. It had hoped to
build the first sub-critical reactor in the UK, but seems to be giving up on
Britain and locking up a deal to build it in China instead, where minds and
wallets are more open.

So the Chinese will soon lead on this thorium technology as well as
molten-salts. Good luck to them. They are doing Mankind a favour. We may get
through the century without tearing each other apart over scarce energy and
wrecking the planet.

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From the Seattle Times – March 18, 2011

by Sandy Doughton

The operator of Washington’s only nuclear-power plant is considering
use of the plutonium fuel that has raised special concerns about one of
Japan’s damaged nuclear reactors.

Officials at the Columbia Generating Station, on the Hanford nuclear
reservation, have been quietly discussing the use of so-called mox fuel
for at least two years — but had hoped to keep the fact out of the news.

In the case of an accident, some experts say fuel made from highly
toxic plutonium can produce more dangerous fallout than standard uranium
fuel. Plutonium fuel is also harder to control, said nuclear scientist
Arjun Makhijani, president of the Institute for Energy and Environmental
Research.

The nuclear-watchdog group Heart of America Northwest sued the
plant’s operator this week, alleging that Energy Northwest improperly
withheld information about the proposal requested under the federal
Freedom of Information Act.

Spokeswoman Rochelle Olson said Energy Northwest and Pacific
Northwest National Laboratory (PNNL) have been discussing the use of
mox, or mixed oxide fuel, but don’t know if they will conduct a
feasibility study. “We have made no decisions,” she said. “The first
priority for us is the safe operation of our nuclear-generating
station.”

Use of plutonium reactor fuel could help draw down stockpiles from
weapons production and dismantling of nuclear warheads, Olson said. And
because the country is anxious to find an application for it, plutonium
fuel could be cheaper.

No U.S. nuclear plants currently use the plutonium fuel.

This week, Japan deployed firetrucks and helicopters to dump water on
the No. 3 reactor at the Fukushima Daiichi nuclear complex, where
stored fuel rods are overheating and containment structures may have
been damaged. The reactor is the only one in the complex to use mox
fuel.

“The possibility of a very significant plutonium release and
subsequent plutonium contamination of areas around the plant … is a
very big issue at reactor 3,” said Dr. Ira Helfand, of Physicians for
Social Responsibility, an anti-nuclear group.

What it is

Even uranium fuel contains some plutonium, which is produced during
the fission process. Mox fuel, which is a mixture of uranium and
plutonium, contains a higher proportion of plutonium — between 5 and 9
percent, Makhijani said. Plutonium has a half life of 250,000 years.
Inhaling a few particles can cause lung cancer.

The National Nuclear Security Administration (NNSA) is building a
$4.8 billion plant to turn weapons-grade plutonium into fuel at the
Department of Energy’s Savannah River site in South Carolina. But so
far, few utilities have expressed interest in using it.

Hanford’s nuclear experts are experienced in handling weapons-grade
material, Olson said. “It makes sense for us to study the technology to
see if it’s feasible.”

But officials wanted to keep their studies quiet. “I assume this info
will stay between PNNL and DOE NNSA,” said a December 2009 e-mail
released last year to the environmental group Friends of the Earth under
a public records request. “Just don’t want any unexpected press
releases about burning MOX fuel in (Columbia Generating Station).”

Other documents lay out a timeline starting in 2013 with
incorporation of a few plutonium fuel elements into the reactor core.
The elements would be tested for six years, followed by a phase-up to
full operations in 2025. Even then, mox fuel would only make up 30
percent of the reactor core.

Olson said the timeline was theoretical, and is already outdated. All
cost estimates were redacted from the released documents, triggering
this week’s legal challenge.

“Nasty stuff”

Some nuclear experts question whether plutonium fuel is significantly
more dangerous than uranium fuel. In an accident, it’s the easily
dispersed isotopes like radioactive iodine and cesium that account for
most of the health effects, Makhijani said. Plutonium is heavy and
wouldn’t be widely spread.

But its toxicity is so high that even small amounts can be dangerous.
“Plutonium is nasty stuff and you don’t want it in the environment,”
Makhijani said.

Olson pointed out that the 1,150-megawatt Columbia Generating Station has never experienced a radiation release.

Commissioned in 1984, the plant produces about 9 percent of
Washington’s electricity. Energy Northwest has applied for relicensing
by the Nuclear Regulatory Commission. If granted, the new license would
be good until 2043.

Incorporating mox fuel would require a license modification, Olson said.

Because only a small amount of plutonium is left after the fuel is
burned, spent rods would not be a target for terrorists intent on making
weapons, she added.

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From Alberta Farmer Express – April 8, 2011

Canada’s sampling and testing regime for radiation from Japan’s nuclear crisis has been expanded to include domestically-produced milk from British Columbia along with food products imported from Japan.

The Canadian Food Inspection Agency emphasized in a statement Wednesday that it has yet to detect related radionuclides — atoms or atomic particles emitting radiation — at or above Health Canada’s “action levels” in any of the products it’s sampled.

The expansion of testing to include B.C. milk was described strictly as “a prudent measure (taken) out of an abundance of caution to reaffirm the safety of this dietary staple for the majority of Canadians.”

“Negligible” levels of radioactivity have been detected along North America’s West Coast, the agency said Wednesday. Radiation levels found on the West Coast are now “less than the natural levels of radiation that would be detected when it rains or snows,” CFIA said.

Four samples of domestically-produced milk from B.C. had been tested by Wednesday to verify that milk remains safe for consumption, CFIA said. All were below Health Canada action levels for “pertinent radionuclides.”

“Additional products may be assessed in the future as the situation evolves and circumstances warrant,” CFIA said.

Imports

Even before the earthquake and tsunami that hit Japan on March 11, Japanese food products made up less than 0.3 per cent of Canada’s total food imports, and imports from Japan are now at “very low” levels.

So far, CFIA said Wednesday, it has tested nine samples from Japanese food and feed imports and found all products below Health Canada’s action levels for radionuclides.

The agency’s testing approach targets the commodities that would pose the greatest potential risk to consumers, such as fresh fruits and vegetables, and also includes a broader range of other commodities, CFIA said.

If any products are found with levels above Health Canada’s action levels for radionuclides they’d be disposed of following protocols from the Canadian Nuclear Safety Commission, the agency said.

Since April 1, CFIA has blocked entry of any food or feed from Japan without acceptable documentation or test results verifying its safety, if the food or feed comes from any of 12 prefectures affected by the ongoing nuclear crisis. The Canada Border Services Agency (CBSA) now refers all shipments of food and feed from Japan to CFIA’s National Import Service Centre.

Japan is still battling to control nuclear reactors in the country’s northeast that were damaged by the quake and tsunami. Workers have recently been able to stop radioactive water leaking into the ocean from the damaged reactors, but experts have said the reactors are still far from being under control.

That said, the Reuters news service on Wednesday quoted a United Nations official as saying the reactor accident is not expected to have any serious impact on people’s health, based on the information available now.

Total diet

CFIA noted Wednesday that the federal government already collects information on normal background levels of radionuclides in food as part of Health Canada’s total diet study.

The total diet study is a survey used to estimate Canadians’ exposure to various contaminants through the food supply. The data collected provides a baseline of the normal levels of such materials in food.

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From the Vancouver Observer – April 1, 2011

by Linda Solomon

How do we know how much radiation is reaching Canada from Fukushima?
Physicians for Global Survival asked, in a press release today.  They
added that physicians for Global Survival “would like more openness from
safety regulators and government about all isotopes, honesty about
methods of measurement and regular updates about risks to vulnerable
populations.”

 “Physicians for Global Survival  is deeply
concerned about the long term health of populations exposed due to
accidental or planned releases of radioactivity from Fukushima and from
domestic power plants.”

How the US monitors radiation

“The US uses a system of RadNet monitors,” the release said, adding that:

Radiation monitors are “point source” monitors, meaning that the
radioactive element or ray must actually strike the monitor to be
measured.  They are unlikely to detect radiation as close as twenty five
feet above or beside them.  Apparently there are only about 125 of
these monitors for the entire continental United States, Hawaii and
Alaska.

Feel secure yet?

“News reports mention Iodine-131 and Cesium-137, not because they are
the only radioactive elements discharged from the stricken reactors in
Fukushima, but because they are the easiest to detect and measure,” the
report added. 

“They both give off gamma rays (like x-rays for
which technicians wear little badges) when they decay.  Iodine releases
gamma rays directly and cesium, indirectly when its short-lived decay
product, barium-137m, undergoes further decay.”

 What about Canada?

According
to reports from the Gentilly 2 reactor in Quebec, there are 48
radioactive elements identified in regular emissions and, according to
the Canadian Nuclear Safety Commission, there may be more than 225
radioactive elements produced in a fully functioning nuclear reactor. 
Aside from plutonium, news reports are silent.

 Alpha and beta
radioactivity are more difficult to measure.  RadNet measures them by 
“vacuuming” the air and passing it through a filter.  The amount on the
filter is then measured.  Sources are contradictory about amount of time
between detection, measurement and speed at which the public can be
informed. 

 Because of their poor external penetrance – alpha
particles can’t penetrate skin and beta particles don’t go much further
than a few millimeters – their danger has been discounted.  As internal
emitters, however, their damage can be extensive.  Absorbed in a human
body through eating or breathing, they can change enzymes, dislodge
ions, and upset strands of DNA.     

 Radioactive iodine-131
causes cancer by this type of mechanism.  The human body absorbs iodine
from food for the production of a thyroid hormone that is important for
normal growth, intellectual ability and daily energy – ask anyone who
has had a “low” thyroid.  While in the thyroid, radioactive iodine emits
beta particles.  Cells have genes which determine their rate of growth
and life spans.  Beta particles alter these genes and, eventually, in
those who develop cancer, turn off the “growth control” gene so that
cells grow wildly out of control producing cancer.

 Fortunately
the danger from radioactive iodine is relatively short-lived.  With a
half-life of  eight days, one tonne becomes a mere 62.5 kilograms in a
month.  The danger can be decreased but not eliminated by taking
potassium iodide tablets immediately before exposure.

Iodine-131,
however, is not the only radioactive element released from Fukushima –
or from any nuclear power plant, the group said in the news release.

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