Technical Guidance

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 mostly considers the maths / physics behind this situation which has been developed for Ionactive by Chris.  

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.

A radiation protection widget which calculates dose rates from an x-ray tube for a given kV, mA and filter (Al). This resource is strictly for training / educational use - that said, as a ballpark resource it gets pretty close to what you might expect from a typical x-ray tube.

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.