Looking at some An-225 images, i see some radioactive signs near the nose radome. Why they are there? I'm sure it doesn't have a nuclear reactor on board or any nuclear medical equipment. The only thing that comes to mind is nuclear density gauges or something related to the radar. Does other planes also use radioactive materials for the same purpose? I've never see, read or heard of any plane using radioactive materials except for propulsion.

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Does the Antonov An-225 have an Auxiliary Power Unit (APU)?


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    $\begingroup$ You probably should highlight the symbols - I had to copy the image and zoom in to determine where the symbols are located $\endgroup$ Commented May 21, 2020 at 20:59

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"Radiation" is a broad term and does not always imply radio active isotope material. High power radar units can have adverse effects on the human body.

The power that radar systems emit varies from a few milliwatts (police traffic control radar) to many kilowatts (large space tracking radars). However, a number of factors significantly reduce human exposure to RF generated by radar systems, often by a factor of at least 100:

  • Radar systems send electromagnetic waves in pulses and not continuously. This makes the average power emitted much lower than the peak pulse power.
  • Radars are directional and the RF energy they generate is contained in beams that are very narrow and resemble the beam of a spotlight. RF levels away from the main beam fall off rapidly. In most cases, these levels are thousands of times lower than in the main beam.
  • Many radars have antennas which are continuously rotating or varying their elevation by a nodding motion, thus constantly changing the direction of the beam.
  • Areas, where dangerous human exposure may occur are normally inaccessible to unauthorized personnel.

The warnings are likely due to the emissions of the radar units in the dome.

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    $\begingroup$ Radar is non-ionising radiation which has its own hazard symbol. The trefoil symbol is specifically for ionising radiation only. $\endgroup$
    – Sanchises
    Commented May 21, 2020 at 20:46
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    $\begingroup$ @Sanchises, well, the fact is, this symbol is commonly used for strong microwave rarar radiation. At least in Russia (or Ukraine for that matter). For example, on Su-27. $\endgroup$
    – Zeus
    Commented May 22, 2020 at 0:57
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    $\begingroup$ ..which is unfortunate as the hazard profile is different:( $\endgroup$ Commented May 24, 2020 at 6:16

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