Ionactive Radiation Protection Blog

In the UK a Radiation Protection Adviser (RPA) appointment is usually required for work involving ionising radiation (Ionising Radiations Regulations 2017 - IRR17).  Where a designated area is declared (e.g Controlled Area), the employer will need local rules - and this requires the appointment of a Radiation Protection Supervisor (RPS). What should the availability of the RPA  / RPS be for a particular use of ionising radiation? 24/7, or as needed (or as written into a contract, job description or appointment letter)? Let's explore this further. 

This article is somewhat in two parts. We consider some recent updates from the UK HSE interpretations on what ‘a person being able to enter a radiography cabinet’ means. They have provided some useful information on a number of x-ray cabinet systems that have been reviewed, and whether they consider can be reasonably entered by a person. They have specified if a registration or consent is required (based on ability to enter)  - which appears to suggest that the cabinets are used for industrial radiography. What if you are not undertaking industrial radiography (NDT – non-destructive testing), but instead using the very same cabinet to x-ray a museum specimen,  visualising the internal structure and acquire knowledge about it’s origin, state, or composition?

You have decided on the make and model of your new laboratory X-ray sterilisation unit. No radioactive HASS sources to worry about, no environmental permit and no security arrangements. You are about to apply for a 'radiation generator registration' from the UK HSE - until you are told otherwise (by the HSE, your RPA or your equipment supplier). You are told you need a consent for industrial irradiation. You are told you need to complete a safety assessment, prepare for an HSE inspection and pay a fee (significantly more than for a registration). For a desktop x-ray unit.? Let's discuss! 

Where does the magic < 1 micro Sv/h at 10cm from a surface come from with respect to critical examinations of x-ray cabinet equipment? Why does Schedule 1 of the Ionising Radiations Regulations 2017 (IRR17) contain an apparent exemption for a notification for certain x-ray devices - but all such devices need at least a registration (or consent in certain cases)? What is the 1 micro Sv/h a measure off - equivalent dose, effective dose or perhaps both? Is this value instantaneous dose rate (IDR) or can it be measured and specified as a time averaged value?  Is the < 1 micro Sv/h a de facto legal limit and what are the repercussions of exceeding it? These and other related questions are pondered in this blog - is < 1 micro Sv/h a magic line in the sand? [Updated 19 May 2025 with an interactive radiation  protection widget to test out some of the matters discussed].

Expect the unexpected. Never assume!  Mark Ramsay, Radiation Protection Adviser (RPA) with Ionactive, looks back at a rather interesting two day Radiation Protection Supervisor (RPS) training course. One of the delegates / trainee (X) brought much more to the course then just experience and enthusiasm. In many ways they become a significant course provider ...

Knowing (and admitting) you are wrong about something is professional - but it is still often difficult to do. This latest blog article is partly about such a case where we wrote in some local rules that a dose investigation level was not formally required. This was wrong and a regulator picked up on this, stating it was a requirement of IRR17. We were not correct with our wording - a formal investigation level in terms of a dose which had been 'pre-assessed' in the risk assessment, and was further verified by regular dose rate monitoring (to show the pre-assessment was still valid), was not considered a formal dose investigation level.  Anyway, a formal dose investigation level was placed in the local rules and we are all happy.

Well not quite. In IRR17 - 9(8) 'investigations', the limit specifically relates to 'effective dose of ionising radiation ' (whole body dose). In our featured example, assessed whole body dose for routine work and reasonably foreseeable accidents was no greater than background. No dosimetry was being worn (or needed). In our view the practical method of how you demonstrate if a formal investigation level is exceeded (via dose rate monitoring and pre-risk assessment) was more important (and useful) than simply stating the formal investigation level based on an effective dose. Why were there local rules anyway (?) - because our regulator has stated that all cabinet x-ray systems contain controlled areas, regardless of the output of a risk assessment (which might suggest otherwise).

So, read on!