This Is the Blog That No One Reads...

Sunday, March 27, 2011

1 Mil radiation spike was an error, just 1K

The big news today was a severely high level of radioactivity in reactor 2 at Fukushima, but I have just come across an flash saying that is now reported to have been a mistaken reading. Again, Tepco undermines our confidence.

[Tepco] had said radiation levels reached 10 million times higher than
normal in the cooling system but because the level was so high the
worker taking the reading had to evacuate before confirming it with a
second reading.

A spokesman for Japan's nuclear watchdog, Hidehiko Nishiyama,
said the level of radiation in puddles near reactor two was confirmed
at 1,000 millisieverts an hour.

Saturday, March 26, 2011

Radiation Exposure in Daily Life

from http://eq.wide.ad.jp/110315houshasen_en.html

Sv (sievert) = constant of biological effects of radiation* x Gy (Gray)

(*) X-Ray, γ-Ray = 1

<b>250,000 µSv/year</b>
	 Maximum permitted for staff working in emergency cases (new guideline) 
<b>100,000 µSv/year</b>
	 Maximum permitted for staff working in emergency cases 
<b>50,000 µSv/year</b>
	 Maximum permitted for Radiation workers and management workers (Policeman and Firemen)
<b>10,000 µSv/year</b>
	Guarapari Beach, Brazil
<b>6,900 µSv/tomography</b>
	Chest X-Ray computed tomography (ont time)
<b>2,400 µSv/year</b>
	Natural Radiation per person/year (World Average)
		Space  0.39
		Food 0.29
		Earth 0.48
		Radon (in air) 1.26
<b>1,000 µSv/year</b>
	Regular public space (except medical area)
<b>600 µSv/radiograph</b>
	Abdominal X-Ray for health checkup (one time)
<b>400 µSv/year</b>
	Domestic Natural Radiation variation (Gifu - Kanagawa)
<b>200 µSv/roundtrip</b>
	Tokyo - New York Flight (radiation varies depending on the flight attitude)
<b>50 µSv/radiograph</b>
	Chest X-Ray for health checkup (one time)
<b>50 µSv/year</b>
	Nuclear Power Plant area (Light Water Reactor) (estimated value)
<b>22 µSv/year</b>
	Evaluation of radioactive emission from nuclear reprocessing plant
<b>10 µSv/year</b>
	Clearance Level (estimated value)

morning update

via cnn--Tests showed that levels of radioactive iodine in seawater just offshore
of the embattled Fukushima Daiichi nuclear plant are more than 1,250
times higher than normal, Japan's nuclear and industrial safety agency
said Saturday.Its potential effect on Japan's fishing industry -- even if consumers
stay away, for simple fear of contamination -- remains a major concern.
So, too, is the fact that authorities have yet to pinpoint the exact
source of the radiation, and thus to determine if it's stopped.

via nature -- Core of reactor 3 possibly breached. Japan's Nuclear and Industrial Safety Agency today said this was highly likely, NHK TV reported,
and that the highly-contaminated water at the plant seems likely to
have come from the core, not spent fuel ponds. Reactor 3 is where three
workers were injured yesterday by exposure to high levels of radiation,
when water overtopped their boots while wading through floodwater - now
known to be highly contaminated - in a basement floor.

Reactor 3 also is the only reactor at the plant to use plutonium as
part of a mixed oxide fuel with uranium, increasing the hazards of
leaked radiation. The mix of radionuclides found in the water and published today
by TEPCO, the plant operator, are novel compared to other escapes over
the past two weeks (see image). Fission products so far detected in
escaped radiation have been volatiles such as Cs-137 and I-131 released
during ventings to reduce reactor pressure. The new mix contains
elements that are not volatile, and so must have leaked from broken fuel
rods into the water.
Highly contaminated water pool found today at reactor 1, and pools of contaminated water also found at reactors 2 and 4, Kyodo news reports.
The water in underground parts of the buildings is thought to have come
from either the cores or spent fuel pools – reactor 4 contained no fuel
at the time of the accident, and its fuel rods were being stored in the
pools.

Evacuation zones around plant extended. People
living in the 10km radius beyond the current 20 km evacuation zone, were
today encouraged by the government to leave voluntarily.
TEPCO, the plant operator, is starting to switch from
seawater to freshwater to cool the reactors as salt crusts on the rods
were hampering flow. The New York Times had an interesting piece earlier this week on the risk of salt crusts resulting in fuel melt.

Japan's science ministry has started posting data from radiation monitoring of coastal waters.
The first samples from 30 km off-shore had surface seawater
concentrations of 24.9 to 76.8 Bq/l of I-131, and 11.2 to 24.1 Bq/l of
Cs-137. For a discussion of what these units mean, see here, and here.

A dilute radioactive cloud has already crossed much of the Northern Hemisphere.
Austria's weather service, the Central Institute for Meteorology and
Geodynamics in Vienna, reported today that 24 radionuclide detecting
stations worldwide run by the Comprehensive Nuclear-Test-Ban Treaty
Organization are now detecting Fukushima fallout as far away as Western
Europe. See report in English here, and the maps here.

Since the Fukushima accident, the CTBTO network, designed to pick up
nuclear tests, has also proven itself to be the key (and indeed unique)
system for detecting worldwide fallout from nuclear accidents, as it emphasized tonight. For my recent article on its role here see "Radiation data from Japanese disaster starts to filter out." Meanwhile, the German Federal Office for Radiation Protection has followed Austria's lead in making its findings from the CTBTO's classified data public.

another explanation of sieverts from nature.

The Latest Word...literally!

Latest update : Oxford English Dictionary

Latest update
March 2011

The latest update of the OED, published on 24 March 2011, revises more than 1,900 entries and adds new words from across the dictionary. The OED's chief editor, John Simpson, provides some observations on the revisions in this update, while Graeme Diamond and Katherine Martin comment on some of the most interesting new words in the batch. A full list of new words can be found below.

mind controlled movement in handicapped person

BrainGate neural interface system reaches 1,000-day performance milestone

“...after 1,000 days a woman who has no functional use of her limbs and is unable to speak can reliably control a cursor on a computer screen using only the intended movement of her hand ...

The woman...performed two “point-and-click” tasks each day by thinking about moving the cursor with her hand. In both tasks she averaged greater than 90 percent accuracy. Some on-screen targets were as small as the effective area of a Microsoft Word menu icon."

Friday, March 25, 2011

more on common knowledge

puzzle red hat, blue hat

Muddy Children and Common Knowledge

Interesting article on common knowledge and a simple form of the red hat problem.

But does he know that I know that he knows?
From No Right to Believe by Ezra Resnick

Five children have been playing together, and three of them have gotten mud on their foreheads. Each child can see mud on others but not on himself. When the children come home, their father says that at least one of them has mud on his forehead; he then asks if anyone can deduce whether there is mud on his own forehead. The children look around, but no one answers. So the father asks again: Does anyone know whether he has mud on his own forehead? Silence. The father then repeats his question a third time, at which point all three dirty children immediately step forward and proclaim that their foreheads must be muddy.