Japanese Government and media reporting about "millisieverts" prompted me to ask wtf is a 'millisievert?' of myself.
- My ongoing ignorance giving me some cause for concern.
For example, I read today that a radiation exposure of 100 mSv (millisieverts=mSv) per year can cause cancer, and that 400 mSv per hour are being recorded at the Fukushima Daiichi nuclear plant. Gibberish to me, and possibly rendering even the dubious journalism/reporting on Japan's radiation 'problem' obtuse, opaque, and meaningless gibberish to many others who are more conversant with the traditional Western units of measurement.
- Also, the words "obtuse, opaque and meaningless" made me think of the Fwench.
In the anglophile world (at least in the US and Australia at present) we STILL use 'curies, rads, roentgen and rem' as units of radiation measurement, BUT......
those oh-so-continental Fwench and the "metric" crowd have a 'new' (at least to me 'new') metric system of 'grays' and 'sieverts' to replace 'rads' and 'rems' [I must admit here I still find it easier to 'think' in terms of yards and gallons than I do in meters and liters].
Called the "Systeme' International" I completely blame the Fwench for this "metric' nonsense re: radiation measurement!
OK, so I still 'think' in terms of 'rads' for example.
>100 rads=radiation sickness
>250 rads=hemopoietic failure
>250-450 rads=LD (lethal dose) for 50% of the population
So, WHAT do millisieverts (mSv) mean exactly? I've attached the scan of a printout of mSv exposure levels. Skipping the details and the MEGO (my eyes glaze over):
>1,000 mSv=radiation sickness and 4,500 mSv=LD
That puts the above reporting of 100 mSv and 400 mSv into perspective THIS dumkopf can unnerstand.
- Gee, thanks MEDIA and thanks FWENCH for making this so clear!!!! Love 'ya!
Wednesday, 16 March 2011
Radiation biology, "news" and the Fwench.............from Rico
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2 comments:
Hope this helps. And if anyone in Australia is still using Rads send them to the bottom of the class! Even so, mph, gallons (Imperial of course) feet and inches make more sense in everyday use than metric.
When ionizing radiation interacts with the human body, it gives its energy to the body tissues. The amount of energy absorbed per unit weight of the organ or tissue is called absorbed dose and is expressed in units of gray (Gy). One gray dose is equivalent to one joule radiation energy absorbed per kilogram of organ or tissue weight. Rad is the old and still used unit of absorbed dose. One gray is equivalent to 100 rads.
1 Gy = 100 rads
Equal doses of all types of ionizing radiation are NOT equally harmful. Alpha particles produce greater harm than do beta particles, gamma rays and x rays for a given absorbed dose. To account for this difference, radiation dose is expressed as equivalent dose in units of sievert (Sv). The dose in Sv is equal to "absorbed dose" multiplied by a "radiation weighting factor"
Type and energy range
Radiation weighting factor, WR
Gamma rays and x rays 1
Beta particles 1
Neutrons, energy
< 10 keV 5
> 10 keV to 100 keV 10
> 100 keV to 2 MeV 20
> 2 MeV to 20 MeV 10
> 20 MeV 5
Alpha particles 20
Equivalent dose is often referred to simply as "dose" in every day use of radiation terminology. The old unit of "dose equivalent" or "dose" was rem.
Dose in Sv = Absorbed Dose in Gy x radiation weighting factor (WR)
Dose in rem = Dose in rad x QF
1 Sv = 100 rem
1 rem = 10 mSv (millisievert = one thousandth of a sievert)
1 Gy air dose equivalent to 0.7 Sv tissue dose (UNSEAR 1988 Report p.57)
1 R (roentgen) exposure is approximately equivalent to 10 mSv tissue dose
What effects do different doses of radiation have on people?
One sievert is a large dose. The recommended TLV is average annual dose of 0.05 Sv (50 mSv).
The effects of being exposed to large doses of radiation at one time (acute exposure) vary with the dose. Here are some examples:
10 Sv - Risk of death within days or weeks
1 Sv - Risk of cancer later in life (5 in 100)
100 mSv - Risk of cancer later in life (5 in 1000)
50 mSv - TLV for annual dose for radiation workers in any one year
20 mSv - TLV for annual average dose, averaged over five years
What are the limits of exposure to radiation?
The Threshold Limit Values (TLVs) published by the ACGIH (American Conference of Governmental Industrial Hygienists) are used in many jurisdictions occupational exposure limits or guidelines:
20 mSv - TLV for average annual dose for radiation workers, averaged over five years
1 mSv - Recommended annual dose limit for general public (ICRP - International Commission on Radiological Protection).
This is a great read and a great article.
I have gone through and checked all the links from the article.
In anticipation of when the information is hid from US the public, I saved the links.
[ BREAKING: EU Energy Chief Says Possible Catastrophic Events In Next Hours ]
http://www.zerohedge.com/article/eu-energy-chief-says-possible-catastrophic-events-next-hours
I thought I would put in a link. because as someone has stated before, they lie to us. They also with hold information.
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