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Controversy? 500 millisieverts per hour at No. 2 says TEPCO spokesman, 500 microsieverts says Japan nuclear agency — 100 millisieverts beyond 30 km radius says Edano

Published: March 23rd, 2011 at 1:55 pm ET
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Smoke disrupts nuke plant restoration work, radiation fears reach Tokyo, Kyodo, March 23, 2011 at 1:03 pm EDT:

… Chief Cabinet Secretary Yukio Edano unveiled estimates that people outside of a 30-kilometer radius of the plant, in which residents have been ordered to evacuate or remain indoors, could be exposed to radiation of 100 millisieverts or more, an annual dose believed to be associated with an increased risk of cancer. …

At the No. 2 reactor, workers have been unable to replace a pump to help revive its internal cooling system since Friday as high-level radiation of at least 500 millisieverts per hour was detected at its turbine building, the spokesman said.

Read the report here.

Radiation at 500 microsieverts/hr at Japan No. 2 unit, Reuters, March 23, 2011 at 12:31 pm EDT:

Radiation at the crippled Fukushima No.2 nuclear reactor was recorded at 500 microsieverts per hour on March 18, Japan’s nuclear safety agency said on Wednesday.

Read the report here.

If it were 500 microsieverts, would that be high enough to halt work at the reactor? NEWS ADVISORY: Repair work halted at reactor No. 2 — Temp rising at No. 1

Published: March 23rd, 2011 at 1:55 pm ET
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March 23rd, 2011 | Tags: , , , , | Category: Radiation Releases, Reactor No. 2, Strange
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7 comments to Controversy? 500 millisieverts per hour at No. 2 says TEPCO spokesman, 500 microsieverts says Japan nuclear agency — 100 millisieverts beyond 30 km radius says Edano

  • xdrfox
    March 24, 2011 at 2:19 am

    Radiation exposure
    Two types of radiation:
    - Ionizing – of sufficiently high energy to ionize atoms (ie to knock out an electron, leaving the atom with a positive charge)
    - may be produced by nuclear reactors, also naturally occurring;
    - can damage living tissue;
    - includes alpha particles, beta radiation, X-rays and gamma rays;
    - Non-ionizing – does not have sufficient energy to ionize atoms
    - – effects on the body not well understood;
    - Includes electromagnetic radiation, visible light, infrared, microwaves, radio waves
    Sources of ionizing radiation exposure in the environment:
    - Natural sources – cosmic rays, sunlight, low levels in food, water and the environment
    - Artificial sources – x-rays, radiological medicine, CT scans, low level exposure from nuclear power stations, air travel
    Equivalent dose (or dose equivalent)
    - This is a measure of ionizing radiation exposure that combines amount of radiation absorbed by human tissue with the medical effects of that type of radiation – allows comparison of exposure levels of different types of radiation;
    - Measured in sieverts (Sv)
    - One sievert is 1,000 millisieverts (mSv). One millisievert is 1,000 microsieverts.
    Exposure levels and their effects
    - 2mSv per year – typical background exposure from the environment
    - 2.4 mSv per year – average dose to US nuclear industry workers
    - 9 mSv per year – exposure to airline crew flying between New York and Tokyo
    - 20 mSv per year – current limit (averaged) for nuclear industry employees and uranium miners
    - 100mSv per year – lowest level at which any increase in cancer risk is clearly evident
    - 1000mSv (1 sievert) – cumulative – estimated to cause a fatal cancer many years later in 5 out of every 100 people exposed to it
    - 1,000mSv (1 sievert) – single dose – temporary radiation sickness – not fatal
    - 5,000mSv (5 sieverts) – single dose – fatal within a month to half of those who receive it
    - 10,000mSv (10 sieverts) – single dose – fatal within weeks.
    (these figures are from the World Nuclear Association and have been widely circulated – but should be treated with caution as they are in many cases estimates)


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  • Ian Gregory
    March 24, 2011 at 7:34 pm

    What are millisieverts compared to rem or rad units? To be honest to have something described as x no of millisieverts per hour does NOT help, in fact it confuses.

    Clarification would be a great help – and it’s not use saying that they are comparable to a chest X-ray or so on, most people would not know what is meant.

    Try using plan simple English language that people CAN understand instead of being un-necessarily confusing.


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  • xdrfox
    March 24, 2011 at 10:04 pm

    What’s the Difference Between Roentgen, Rad and Rem Radiation Measurements?
    CONVERSION
    http://www.stevequayle.com/ARAN/rad.conversion.html


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  • xdrfox
    March 25, 2011 at 12:04 am

    Radiation Dose Chart
    Find Your Estimated Annual Radiation Dose

    http://www.new.ans.org/pi/resources/dosechart/msv.php


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  • dragonsprayer
    March 27, 2011 at 12:41 pm

    good info!

    500 rads kills so sivert must equal around 10 rads from the fatal dosage.


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