Technical Guidance

An animated video explaining how the Geiger-Muller tube functions - a classic radiation detector which was envisaged in 1908,  practically built in 1928, and is still a widely used detector today in 2024 (nearly 100 years later!). 

Imagine a radioactive source holder breaking away from an industrial nuclear gauge  - forming a small aperture from which gamma rays can be emitted. What would the dose rate be at various distances from the aperture, and what % of the body trunk would be exposed at each distance? When would an equivalent dose to a part of the body become a whole body effective dose? This interactive widget sets out to answer these questions. 

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. 

This resource uses a radiation protection widget to explore the validity of a popular gamma dose rate formula of the form:

\[ \begin{align} D_{\mu Sv hr^{-1}} &= \frac{AE}{6 r^2 } \end{align} \]

where D is dose rate in µSv/h, A is activity in (MBq), E is gamma ray energy in MeV, and r is the distance in m.

Large volumes of water (in pools / ponds) are often used for radiation shielding, particularly for spent nuclear fuel and high activity Co-60 sources in industrial irradiation facilities. The water provides shielding and cooling whilst allowing remote movement of highly radioactive items where operators stand safely outside the pool. Imagine falling in - how would you fair? Very well if you can swim as illustrated in this radiation protection widget.

Use this interactive ALARP / ALARA calculator widget to investigate the effect of time, distance and shielding on radiation dose rate and accumulated exposure. A great radiation protection training / educational aid - learn the concepts first, then investigate them interactively! Explore how best to optimise exposure by using a combination of all three protection methods.