Time, distance and shielding

Radiation protection rules of thumb, frequently asked questions, hints and tips related to time, distance and shielding considerations.

  • Skyshine – radiation scattering around and over shielding

    Published: Sept 29, 2021

    Source: Ionactive Radiation Protection Resource

      Tags:
    • Skyshine
    • Radiation Shielding
    • Open top radiography
    • Radiation scatter
    • Radiation skyshine widget

    A easy to read explanation of radiation skyshine (usually x-ray or gamma ray photons, or neutrons) which can leave an open topped (or lightly shielded) enclosure at height, and reach ground level some distance away. In some cases skyshine can yield a peak ground level dose rate which is some distance away from the shielding wall. 

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  • Protection by reducing exposure time - is it always valid?

    Published: Sept 29, 2021

      Tags:
    • Ionising Radiation
    • Protection by time
    • Very high dose rates
    • High activity Co
    • HASS source
    • Pure alpha emitter
    • Po-210
    • Polonium-210
    • Cabinet x-ray systems
    • < 1 μSv/h
    • < 1 micro Sv/h

    Protection by reducing exposure time to ionising radiation is a recognised practice. However, are there occasions where this is not so valid (or not valid at all )? This guidance provides some examples to illustrate this. 

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  • Inverse Square Law - when is a source a point source?

    Published: Sept 29, 2021

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Physics is, hopefully, simple. Physicists are not

– Edward Teller -