45 percent of children in Japan’s Fukushima Prefecture were exposed to thyroid radiation: Report
Of more than 1,000 children screened for radiation exposure in Fukushima Prefecture, Japan, 45 percent have tested positive for thyroid radiation exposure, according to a statement by the Nuclear Safety Commission published today, a report said.
The survey was conducted on 1,080 children from newborns to age 15 in the cities of Iitate, Iwaki and Kawamata between March 26 and 30 following the radiation leak caused by the core meltdown in Fukushima Dai-Ichi NPP.
The amounts of exposure averaged about 0.04 microsievert per hour, the report said. “The largest exposure was 0.1 microsievert per hour, equivalent to a yearly dose of 50 millisieverts for a 1-year-old.”
Contaminated Soil
Soil samples taken at four locations in Fukushima City on June 26 were found to contain radioactive cesium of up to 46,000 becquerels per kilogram, or nearly 5.6 times the legal limit of 10,000 becquerels per kg.
In one area of the city contamination levels exceeded 931,000 becquerels per square meters.
Half-life of some radioactive elements
[NOTE: Half-life is the time taken for a radioactive substance to decay by half.]
- Cesium-134 ~ 2 years
- Cesium-137 ~ 30 years
- Iodine-131 ~ 8 days
- Plutonium-239 ~ 24,200 years
- Ruthenium-103 ~ 39 days [Ruthenium is a fission product of uranium-235.]
- Ruthenium-106 ~ 374 days
- Strontium-90 ~ 28.85 years [Strontium-90 is a product of nuclear fission and is found in large amounts in spent nuclear fuel and in radioactive waste from nuclear reactors.]
- Uranium-234 ~ 246,000 years
- Uranium-235 ~ 703.8 million years
- Uranium-238 ~ 4.468 billion years
What is a lethal dose of radiation from a single Exposure?
Studies of the 1945 atomic bombing at Hiroshima and Nagasaki show that 100 percent of victims whose bodies were exposed to 600,000 millirems (6,000 mSv) died from radiation. About 50 percent of victims who received 450,000 millirems (4,500 mSv) of radiation also died.
(Note: Rem is a unit of ionizing radiation equal to the amount that produces the same damage to humans as one roentgen of high-voltage x-rays. Source: MIT)
1 rem = 10 mSv (1 Sv = 100 rem)
Background Radiation in millirems per year (mrem/yr)
- Average background radiation (US): 300
- Higher altitudes (eg. Denver): 400
“Safe Levels” of Radiation (U.S.)
Limits above natural background radiation levels (average 300 millirems per year) and medical radiation:
- Occupation Limit: Maximum of 5,000 (the limit for a worker using radiation)
- Average Natural Background: 300
[Note: Lifetime cumulative exposure should be limited to a person’s age multiplied by 1,000 millirems, e.g., a 70-year-old person, 70,000 millirems.]
Adults
- Max single dose for an adult: 3,000
- Annual total dose: 5,000
Under 18
- Max single dose for a person aged under 18 years: 300 millirems (whole body equivalent)
- Annual total exposure: 500
Fetal Exposure
- Maximum limit for fetal exposure during gestation period: 50 millirems per month above background levels
Medical
- Single Chest X-ray (the whole body equivalent): 2 millirem
Air Travel
- Coast-to-coast US round trip flight: 12 millirems
Probability of a Nuclear Disaster by Country
The following probability figures are calculated by FIRE-EARTH on April 8, 2011
- Japan (880)³
- United States (865)
- France (855)
- Taiwan (850)
- Belgium, China, Finland, India, South Korea, United Kingdom, Ukraine, Russia, Slovakia, Czech Republic, Armenia, Slovenia, Croatia, Romania, Hungary, Bulgaria, Spain, Pakistan, Argentina, Brazil, Mexico, South Africa, Canada (810)
- Germany, Sweden, Netherlands (800)
- Switzerland (750)
Notes:
- The list represents a snapshot of events at the time of calculating the probabilities. Any forecast posted here is subject to numerous variable factors.
- Figures in the bracket represent the probability of an incident occurring out of 1,000; the forecast duration is valid for the next 50 months.
- Probability includes a significant worsening of Fukushima nuclear disaster, and future quakes forecast for Japan.
- A nuclear incident is defined as a level 5 (Accident With Wider Consequences), or worse, on the International Nuclear and Radiological Event Scale (INES). See below.
- Safety issues considered in compiling these lists include the age, number of units and capacity of nuclear reactors in each country/state, previous incidents, probability of damage from human-enhanced natural disasters, e.g., earthquakes, tsunamis, volcanic activity, hurricanes, tornadoes, storms, wildfires, flooding… ]
- The Blog’s knowledge concerning the extent to which the factors described in (3) might worsen during the forecast period greatly influences the forecast. (Last UPDATED: June 26, 2011)
Fire Earth 