Sunday, 27 March 2011

radioactivity: dosimetry + fukushima links



Measuring radioactivity can be confusing: various units coexist for different purposes. Different units allow measurement of the exposure intensity, the activity of the source, the absorbed dose and the effective biological dose. The main units in use are rem, gray, rad, sievert and becquerel. If radioactivity is compared to a rainstorm, the amount of rain falling would be measured in Becquerels, the amount of rain hitting you would be measured in grays, and how wet you get would be measured in sieverts ( This summary intends to ease understanding the values. The natural background radiation, like radon gaz and high altitude exposure with air travel shouldn't be added to the calculus in most instances or has to be stricly differentiated.

map of background radiation in Britain (source)

A war is ongoing between scientists concerning the
doses and the model of the International Commission on Radiological Protection (ICRP). One side pulls the concept of "there is no safe dose" which could put an end to nuclear electricity production as well as some medical radiations and nuclear weapons (see ECRR and ECRR Risk Model and radiation from Fukushima) because if there is no safe dose, no one can be exposed and thus cannot maintain the equipments. The nuclear industry side claims that  it's safe to produce nuclear energy.

The units used to measure ionizing radiation are rather complex. The ionizing effects of radiation are measured by units of exposure.

The roentgen (symbol R) is the amount of radiation required to liberate positive and negative charges of one electrostatic unit of charge (esu) in 1 cm³ of dry air at standard temperature and pressure (STP). It is not itself an SI unit and continued use is "strongly discouraged" by the National Institute of Standards and Technology. Its value is expressed in terms of the SI units electric charge divided by unit mass: coulomb per kilogram (C/kg).

1 R ≈ 0.258 mC/kg
1 mC/kg ≈ 3.88 R
1 R/h = 71.7 nC/kg.s
1 nC/kg.s = 0.014 R/h

Roentgen/hour (numerical equivalent)=0.12 gray (Wr=1, X-ray, gamma ray, electrons) 1 Roentgen/hour (numerical equivalent)=0.006 gray (Wr=20, alpha particles)


Old Unit: the curie (symbol Ci) is roughly the activity of 1 gram of the radium isotope 226Ra or 15g of 239Pu . New SI unit: the becquerel (symbol Bq) is defined as the activity of a quantity of radioactive material in which one nucleus decays per second .

1 Ci = 3.7×1010 Bq
1 Ci = 37 GBq
1 μCi = 37,000 Bq 1 Bq = 2.70×10−11 Ci 1 Bq =2.70×10−5 μCi
1 GBq = 0.0270 Ci
1 TBq = 27 Ci

The typical human body contains roughly 0.1 μCi (=37,000 Bq) of naturally occurring potassium-40
Activity of one ton of Uranium 238 = 0.3 Ci = 11.1 GBq
Activity one gram of plutonium 239 = 2.3 GBq

Definition of
contaminated zones after the Chernobyl disaster: 37 kBq/m2 of Cs-137 (= 1 Ci/km2)
Natural radioactiviy

Rain water: 0.3 à 1 Bq/L
River water : 0.07 Bq/L (226Ra et descendants) ; 0,07 Bq/L (40K) ; 11 Bq/L (³H)
Sea Water: 14 Bq/L (40K mainly)
Mineral Water : 1 -à 2 Bq/L (226Ra, 222Rn)
Milk: 60 Bq/L
Human body: 8,000 to 10,000 Bq



Old unit: the rad or rd (Radiation Absorbed Dose)

New SI unit: the Gray (Gy) measures the deposited energy of radiation.

1 Gy = 1 Joule of ionizing radiation per kilo of body tissue
100 rad = 1 Gy
1 rad = 0.01 Gy

A whole-body exposure to 5 or more Gy of high-energy radiation at one time usually leads to death within 14 days. Hair loss may be permanent with a single quick dose of 10 Gy.

A slow rate of an identical exposure dose has a lesser impact than a quick one.



Old unit: the rem [Roentgen (or rad) equivalent in man (or mammal)]

New unit: the Sievert (Sv) attempts to quantitatively evaluate the biological effects of ionizing radiation as opposed to the physical aspects, which are characterised by the absorbed dose, measured in gray. The equivalent dose to a tissue is found by multiplying the absorbed dose (Gy) by a "quality factor" Q, dependent upon radiation type, and by another dimensionless factor N, dependent on all other pertinent factors.N depends upon the part of the body irradiated, the time and volume over which the dose was spread, even the species of the subject. Together, Q and N constitute the radiation weighting factor, WR (1)

1 Sievert = 100 rem
1 rem = 0.01 Sv
The conversion from rad and Gy to rem and Sv, depends of the level of Linear Energy Transfer (LET), a measure of the energy transferred to material as an ionizing particle travels through it (2). The biological effects of alpha particles and neutrons (high LET radiation) are in general much greater than the effects of beta particles and gamma rays (low LET radiation) of the same energy. The Radiation Weighting Factor wR is introduced to take account of the different biological effectiveness of alpha and beta particles, neutrons, X and gamma rays. (TORCH)

For alpha particles and neutrons (which have a HIGH LET):
"Roughly" (I don't want to detail everything here this post is long enough already)
1 rad = 20 rem and 1 Gy = 20 Sv

For beta particles, gamma rays and X-rays (which have a LOW LET)1 rad = 1 rem, 1 Gy = 1 Sv

The international limit for radiation exposure for member of the public is 1 mSv per year, for nuclear workers it is 20 mSv per year, averaged over five years, with a limit of 50 mSv in any one year,[198] however for workers performing emergency services EPA guidance on dose limits is 100 mSv/y when "protecting valuable property" and 250 mSv/y when the activity is "life saving or protection of large populations." The limit to certain parts of the body can reach 500 Sv/y.

1 milliSievert per year ≈ 0.11 microSievert per hour

The ICRP sets the admissible risk for the public at 1mSv / year which corresponds to 5 radio-induced cancers per 100,000 population.

European Committee on Radiation Risk (see ECRR and ECRR Risk Model and radiation from Fukushima) recommends that the total maximum permissible annual dose limit to members of the public involving releases of anthropogenic isotopes or natural isotopes delivered in a novel fashion should be kept below 0.1mSv (nuclear workers should be 2mSv) as calculated using the ECRR model.

The ICRP cancer risk coefficient is about 0.05 per Sievert and that of the ECRR is 0.1 per Sievert. (ECRR)

It is complicated to convert Bq in Sv, (see links below and table 2 ECRR, p.253 Table A1 ECRR and compare the dose coeficient rate Sv/Bq).
To eat 80,000 Bq of wildboar meat (= 2 kg in certain occurences in Bavaria [TORCH]), corresponds to 1 mSv.

Telco in Japan has hiked the radiation exposure limit for its workers at the plant from 100 millisieverts per shift to 150 millisieverts.

Exposure (unprotected) begins to be lethal at 2 Sv/y. Vomiting and hair loss occur at 70 rem and 75 rem respectively, while exposure to 400 rem can mean possible death in two months. (WSJ)

Exposure limits in France:

Medical Scanner: lowest estimates 0.05 mSv ( local), 25 mSv (head), 150 mSv (whole body) according to Wikipedia. The Wall Street Journal says a computer tomography scans, which emit roughly 1,500 microsieverts of radiation, or a full set of dental X-rays, about 400 microsieverts.

The CRIIRAD assesses that in France, 5 to 10,000 people die each year of medical irradiations. (Trait d'union , Criirad, n°6, decembre 1997).


1950-1970: The total radioactivity caused by atomic weapons in the world: +/- 30,000,000 Sv
Chernobyl: 600.000 Sv




Dose is meaningless
Cerrie Majority report says

..... There are important concerns with respect to the heterogeneity of dose delivery within tissues and cells from short-range charged particle emissions, the extent to which current models adequately represent such interactions with biological targets, and the specification of target cells at risk. Indeed, the actual concepts of absorbed dose become questionable, and sometimes meaningless, when considering interactions at the cellular and molecular levels.(CERRIE Majority Report Chapter 2.1 paragraph 11).

In other words, where hot or warm particles or Plutonium or Uranium are located in body tissue
or where sequentially decaying radionuclides like Strontium 90 are organically bound (e.g. to DNA) “dose” means nothing.
This is massively significant. Official radiation risk agencies universally quantify risk in terms of dose. If it means nothing the agencies know nothing and can give no valid advice.Their public reassurances fall to the ground. They can no longer compare nuclear industry discharges with the 2 millisieverts we get every year from natural radiation, or the cosmic rays you’d receive flying to Tenerife for a holiday.Dose is meaningless ... emerging consensus



Russia, Belarus and Ukraine received the highest amounts of fallout while former Yugoslavia, Finland, Sweden, Bulgaria, Norway, Rumania, Germany, Austria and Poland each received more than one petabecquerel (10E15 Bq or one million billion becquerels) of caesium-137, a very large amount of radioactivity.

In the particular case of thyroid cancer, there is evidence that the risk is directly proportional to dose, down to doses as low as 10 mSv

CRIIRAD maintains that as a result of the Chernobyl accident there are still ‘accumulation points’ above 1 500 metres altitude across the entire alpine arc where the soil presents such high levels of radioactivity that it must be considered low‑ to medium‑level radioactive waste(1). In some places in France, CRIIRAD has taken caesium 137 soil contamination readings of over 500 000 Becquerels per kilo...(question of MEP Marco Cappato to the European Commission)

Restrictions on Food Still in Place In many countries

Restriction orders remain in place on the production, transportation and
consumption of food still contaminated by Chernobyl fallout: 22% of the surface of Belarus and 6% of Ukraine have been contaminated with levels of Cs-137 superior to 40,000 Bq/m2

In the United Kingdom restrictions remain in place on 374 farms covering 750 km2 and 200,000 sheep.
In parts of Sweden and Finland, as regards stock animals, including reindeer, in natural and near-natural environments.
In certain regions of Germany, Austria, Italy, Sweden, Finland, Lithuania and Poland wild game (including boar and deer), wild mushrooms, berries and carnivore fish from lakes reach levels of several thousand Bq per kg of caesium-137.
In Germany, caesium-137 levels in wild boar muscle reached 40,000 Bq/kg. The average level is 6,800 Bq/kg, more than ten times the EU limit of 600 Bq/kg.

Cotterill et al (2001) reported an increasing incidence of thyroid cancer in the North of England, particularly Cumbria one of the two areas in the UK receiving the heaviest fallout. They pointed out that iodine-131 concentrations in rainwater were as high as 784 Bq/litre and in goat’s milk as high as 1,040 Bq/litre. These concentrations are higher than the EC’s Community Food Intervention Levels shown in table 4.2.(TORCH)

Food contamination limits in Europe (2004)

 ..............................................................................................Cs-134 Cs-137 ....Cs-134 Cs-137
CEE/EU .....................internal production ...........(import) ...... [during a radiological emergency]

dairy products:
..........................................370 Bq................ (600 Bq/kg)...... [1,000 Bq/l]
milk and baby food: ................................
370 Bq/l ...............(370 Bq/l)...... ...[400 Bq/l]
fruits and veg. :
........................................600 Bq/kg............ (600 Bq/kg)...... [other food: 1,250 Bq/kg] 
other products: ........................................600 Bq/kg............ (600 Bq/kg) .......[liquids 1,000Bq/l other products 600 Bq/kg]...............................................................................................................................[condiments 12,500 Bq/l]

dairies 1
Bq/kg id.
baby food 20
Bq/kg id.
other 80
Bq/kg id

dairies 150
Bq/kg id.
baby food 500
Bq/kg id.
other 2,000
Bq/kg id
dairies 75
Bq/kg id.
baby food 125
Bq/kg id.
other 750
Bq/kg id

bread and potatoes 20 Bq/kg
milk: 100 Bq/l
meat: 200 Bq/kg

The above map results for France and Corsica are fake. (see question by MEP Marco Cappato to the European Commission). The Atlas of Caesium Deposition on Europe after the Chernobyl Accident is available online.
Full Version (English and Russian)

Compared with other nuclear events: The Chernobyl explosion put 200 / 400 times more radioactive material into the Earth's atmosphere than the atomic bomb dropped on Hiroshima; atomic weapons tests conducted in the 1950s and 1960s all together are estimated to have put some 100 to 1,000 times more radioactive material into the atmosphere than the Chernobyl accident. (source IAEA)

Chernobyl and the Nevada test site.
The overwhelming attention the media paid to Chernobyl nuclear incident can be contrasted with the virtual media blackout on the nuclear contamination of the American Southwest from more than four decades of the above-the-ground testing of the nuclear bombs on the Nevada Test Site. The fallout clouds from these over 400 nuclear explosions floated across the American Southwest.
Comparisons of radiation level released at Chernobyl with radiation level of the Hiroshima bomb vary substantially, a reasonable estimate is that the Chernobyl radioactive release was equivalent to ten Hiroshima atomic bombs.[200 to 400 times see below].
The aftermath of these nuclear explosions is described by Carole Gallagher (1993, Massachusetts Institute of Technology Press) in her book American Ground Zero. Carole Gallagher spent several years interviewing people who live in Nevada, Utah and Arizona, including Native Americans, farmers, ranchers, professors, housewives, soldiers and artists. What they had in common were leukemia, brain tumors, birth defects, sterility, miscarriages, thyroid cancers ...

WHO is submitted to IAEA censorship

As stated in our letter of 24 March 2007 (attached), the Agreement (WHA 12-40 signed on 28 May 1959) between WHO and the IAEA, prohibits the international health authority from undertakingactivities prejudicial to the interests of the IAEA. WHO thereby loses its freedom and its authority to control and coordinate matters relating to radiation and health. The terms of this Agreement run counter to the constitutional obligations of WHO.

Early in 1990, WHO was invited by the Soviet Ministry of Health to set up an international aid
programme. According to the chronological memorandum issued by Dr Nakajima (Director-General of WHO at the time) during the conference that he convened in Geneva, 20 – 23 November 1995, the international project was undertaken and completed by the IAEA in May 1991. Hence, it was the IAEA, rather than WHO, that provided the information and other aspects of the assistance requested by the Ministry of Health of the USSR.

Oliver Tickell
28 May 2009

...the scientific case against the agreement is building up, most recently when the European Committee on Radiation Risk (ECRR) called for its abandonment at its conference earlier this month in Lesvos, Greece.
At the conference, research was presented indicating that as many as a million children across Europe and Asia may have died in the womb as a result of radiation from Chernobyl, as well as hundreds of thousands of others exposed to radiation fallout, backing up earlier findings published by the ECRR in Chernobyl 20 Years On: Health Effects of the Chernobyl Accident. Delegates heard that the standard risk models for radiation risk published by the International Committee on Radiological Protection (ICRP), and accepted by WHO, underestimate the health impacts of low levels of internal radiation by between 100 and 1,000 times – consistent with the ECRR's own 2003 model of radiological risk (The Health Effects of Ionising Radiation Exposure at Low Doses and Low Dose Rates for Radiation Protection Purposes: Regulators' Edition). According to Chris Busby, the ECRR's scientific secretary and visiting professor at the University of Ulster's school of biomedical sciences:
"The subordination of the WHO to IAEA is a key part of the systematic falsification of nuclear risk which has been under way ever since Hiroshima, the agreement creates an unacceptable conflict of interest in which the UN organisation concerned with promoting our health has been made subservient to those whose main interest is the expansion of nuclear power. Dissolving the WHO-IAEA agreement is a necessary first step to restoring the WHO's independence to research the true health impacts of ionising radiation and publish its findings."


useful links:

2010 Recommendations of the European Committee on Radiation Risk (ECRR)

map of Japan in english

updated map of japanese nuclear power plants

Guidance for Radiation Accident Management

Rapid internal external dose magnitude estimation

Radiations: definitions

Types of radiation exposure

Japan Times emergency assistance in english, resources for foreigners residing in Japan

BBC Edited Guide Radioactivity

BBC EG The measurement of radioactivity


Online unit converter

Activity Conversions

Beta Emitter Dose-Rate <--> Activity Calculations

Gamma Emitter Point Source Dose-Rate <-to-> Activity and Shielding Calculations (In Air)

ALARA Calculations (Time, Distance and Shielding)

WISE uranium calculator

About Geiger counter

Detecting radioactivity

NEWS SITES in english and french

CRIIRAD France fr

The Low Level Radiation Campaign (LLRC)

Fukushima Green Action Japan en

Nuclear information and resource service en

Peak of oil

European Committee on Radiation Risk

ECRR Risk Model and radiation from Fukushima


Kyodo news agency en

Nikkei en

Jiji Press en (via Google News)


The Manichi Daily News en

The Japan Times en

Yomiuri Shimbun en

The Asahi Shimbun en


World Information Service on Energy (WISE)

Green Action Japan en

Greenpeace Fukushima

Exposure limits in France:

International Nuclear and radiological Event Scale ( INES )

map of Japan with significant radioactivity measurments

winds observations for south Tohuku

12 days wind forecast Japan

Global Jetstream Wind
Atlas of Caesium Deposition on Europe after the Chernobyl Accident online.
Full Version (English and Russian)

Live and archived radioactivity

Fuel rod fires plume map
15 march

Northen hemisphere radioactive plume map
15-18 march

USA radioactivity Counts Per Minute (CPM): 60 CPM = 1 Bq

Atlas of Caesium Deposition on Europe after the Chernobyl Accident online.
Full Version (English and Russian)

BibliographyContamination radioactives: Atlas France et Europe, CRIIRAD and André Paris, Editions Yves Michel, 2002, ISBN 2913492150.
(1) Atlas of Caesium Deposition on Europe after the Chernobyl Accident, Eur 16733, Luxembourg, Office for Official Publications of the European Communities, 1998, ISBN 92-828-3140-X (PDF)
Full Version (English and Russian)
THE OTHER REPORT ON CHERNOBYL (TORCH) , Ian Fairlie, PhD, UK. David Sumner, DPhil, UK, Prof. Angelina Nyagu, Ukraine Berlin, Brussels, Kiev, April 2006 COMMISSIONED BY Rebecca Harms, MEP, Greens/EFA in the European Parliament WITH THE SUPPORT OF The Altner Combecher Foundation
Radioprotection 2003, Vol. 38, No 4, pp. 529-542, ‘The Chernobyl fallout in France, critical review measurement-results obtained at that time and lessons learned for crisis management’, Ph. Renaud and D. Louvat (PDF)

2010 Recommendations of the European Committee on Radiation Risk, The Health Effects of Exposure to Low Doses of Ionising Radiation, Chris Busby, with Rosalie Bertell, Inge Schmitz Feuerhake Molly Scott Cato and Alexey Yablokov, Green Audit Press, Castle Cottage, Aberystwyth, SY23 1DZ, United Kingdom 2010 (PDF)

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Alexandre de Perlinghi


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