The Mathematics of Radiation Protection

These articles and guidance look at the mathematics (maths) associated with radiation protection / health physics including half-life, inverse square law, statistics, instrumentation, famous physics equations and much more. If you like your radiation safety served with maths, then this resource section is for you!

  • Criticality and delayed neutrons

    Published: Aug 08, 2024

    Source: Dr Chris Robbins, Grallator / Ionactive radiation protection resource

      Tags:
    • Criticality
    • Critical mass
    • Delayed neutrons
    • Neutrons
    • Nuclear material
    • Fissile material
    • Neutron multiplication factor (k)
    • Fission
    • mean neutron lifetime
    • Prompt neutrons
    • Fission products
    • Eigenvalues
    • Neutron lifetime
    • Reactivity
    • Sub-critical
    • Critical
    • SuperCritical

    An article by Dr Chris Robbins of Grallator looking at the physics and mathematics of delayed neutrons in criticality scenarios.  The article demonstrates that delayed neutrons and neutron lifetime have a significant impact on the increase (or decrease) in power over orders of magnitude. The article is illustrated with screen shots from the new Ionactive criticality widget.  

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  • Radioactive source holders - Dose rate through an aperture

    Published: Apr 23, 2024

    Source: Dr Chris Robbins, Grallator / Ionactive radiation protection resource

      Tags:
    • Shielding aperture
    • Nuclear gauge
    • Nuclear density gauge
    • Radiation through an aperture
    • Whole body exposure
    • effective dose
    • Nuclear gauge accident dose rates
    • Collimated radiation
    • Inverse square law
    • Multi-phase flow meter
    • Radioactivity

    This article, and our discussions with Dr Chris Robbins of Grallator, was born from a consideration of when a radioactive source holder (such as that fitted as part of a nuclear gauge) might become detached during a radiation accident, such that the radiation from the source is exposed directly through a small aperture. This is reasonably foreseeable compared to a radioactive source which might be completely exposed (unshielded). What would the dose rates be at a certain distance from the source holder, and what % of the trunk of the body would be exposed? This article considers the maths / physics behind this situation which has been developed for Ionactive by Chris. Ionactive has then taken the results of this analysis and shown how it would apply to a real world radiation accident. 

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  • Calculate an estimate of x-ray dose rate from an x-ray tube given kV and mA

    Published: Mar 24, 2024

    Source: Dr Chris Robbins, Grallator/ Ionactive Radiation Protection Resource

      Tags:
    • X-ray
    • X-ray dose rate
    • X-ray generator
    • mA
    • kV
    • Calculate x-ray tube output
    • Formula for x-ray tube output
    • Calculate x-ray tube dose rate
    • Anode
    • Cathode
    • Bremsstrahlung x-rays
    • Characteristic X-rays
    • Tungsten target
    • Inverse square law
    • Energy Absorption
    • Mass Energy Absorption Coefficient
    • Gray (Gy)
    • NDT X-ray tube
    • Medical X-ray tube
    • Radiation Protection Adviser (RPA)

    How do you calculate an estimate of dose rate from an X-ray tube give kV and mA? In this resource we consider a 'ballpark' estimate of radiation dose rate using some physics principles, including an estimate of % bremsstrahlung from an anode target, combined with a calculation of power density and consideration of average energy absorption rate.

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  • When \( 1/d^2 \) breaks down - part 2: area source

    Published: Mar 22, 2024

    Source: Dr Chris Robbins, Grallator

      Tags:
    • 1/d2 for an area source
    • Inverse square law
    • radiation
    • radioactive area source
    • Radiation protection mathematics
    • Maths for radiation safety

    When \( 1/d^2 \) breaks down - part 2: area source. Using some mathematics to explore how the inverse square law works with a radiation area source.

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  • When \(1/d^2\) breaks down - part 1: line source

    Published: Mar 22, 2024

    Source: Dr Chris Robbins, Grallator

      Tags:
    • 1/d2 for a line source
    • Inverse square law
    • radiation
    • radioactive line source
    • Radiation protection mathematics
    • Maths for radiation safety

    When \( 1/d^2 \) breaks down - part 1: line source. Using some mathematics to explore how the inverse square law works with a radiation line source.

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  • The accumulated radiation dose when moving up to a source

    Published: Nov 27, 2023

    Source: Dr Chris Robbins, Grallator

      Tags:
    • Dr Chris Robbins
    • Grallator
    • Accumulated dose
    • Maths in radiation protection
    • Radioactive source
    • accumulated radiation exposure moving towards a source
    • Inverse square law
    • Point source

    Consider the situation where you move up to a radioactive source, perform some operations for a period of time, and then move away. What total dose will be received?

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Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less

– Marie Curie -