You have a UK IRR17 Consent. Do you also need a registration for ionising radiation sources?

Consent and registration in the UK

Ionactive has produced considerable free resource on consent and registrations under the Ionising Radiations Regulations 2017 (IRR17) - both in our technical and legislative resource sections, and also in this blog. We will therefore not spend too much time detailing all the specifics of consents and registrations, but will provide a brief summary shortly. If you are not familiar with consents (which for non-nuclear sites will be operating under a new system from October 2023) or registrations, consider the following links below (these will open in a new tab so as not to complicate navigation through this article).

Ionising Radiations Regulations 2017 (IRR17) Guidance - Part 2 - General Principles and Procedures (Ionactive resource). This link takes you to our IRR17 guidance where notification, registration and consent are explained.

New UK Consent process for users of Ionising Radiation (as of February 2023) (Ionactive resource). Inside this link you will find a blog article, updated to May 2023, where you can visit the ONR website and take a peek at the guidance, which is likely to be similar to that provide by the HSE due October 2023. Note that that the guidance may well be modified in the early days of the new consent process (see next link below).

New UK IRR17 consent - dose rate and accelerators
(Ionactive resource). Ionactive already has some issues with the new guidance for consents which you may wish to ponder at this link.

Not withstanding the above noted resource, here is a brief summary of registration and consents under IRR17. As this is a summary we will not make detailed reference to the tables and charts that are essential if you are determining your need for a registration under IRR17 (6) or a notification under IRR17 (5) - this is mentioned in the links presented above.


Registration is the middle tier in the graded approach to regulatory control of ionising radiation in the UK. This is designed to be a risk based approach where notification is the lowest tier (e.g. notification of occupational exposure to radon), and consent is the highest tier with the greatest potential radiation risks (e.g. operation of an accelerator).

The middle tier registrations are for 'certain practices'. A registerable practices falls into the following three categories:

  • Work involving the use of radiation generators.
  • Work with radioactive material containing artificial radionuclides.
  • Work with radioactive material containing naturally occurring radionuclides.

This is a brief summary but we should add the following clarifications

  1. A registration is not required for any of the above if all the conditions in Schedule 1 of IRR17 are met (be very careful here, in our experience it is not often that Schedule 1 is found to be that useful).
  2. A registration is not required, but a consent is, where the above mentioned work falls into a 'specified practice' (so an x-ray generator in the form of an accelerator requires a consent and not a registration, whereas an x-ray generator for diagnostic radiology would need a registration).
  3. A registration may not be required where certain total radioactivity (Bq) and radioactive concentration (Bq/g) are below prescribed values - these are given in IRR17 Schedule 7 (Quantities and concentrations of radionuclides), and the criteria is specified in IRR17 Regulation 6(1)–(5). The interpretation for work with artificial or naturally occurring radioactive material is not always straight forward so seek Radiation Protection Adviser (RPA) assistance as required.

Work which needs to be covered under a consent is rather more easy to state since the work can be selected from a list of specified practices given below.

(a) the deliberate administration of radioactive substances to persons and, in so far as the radiation protection of persons is concerned, animals for the purpose of medical or veterinary diagnosis, treatment or research

(b) the exploitation and closure of uranium mines (*)

(c) the deliberate addition of radioactive substances in the production or manufacture of consumer products or other products, including medicinal products

(d) the operation of an accelerator (except when operated as part of a practice within sub-paragraph (e) or (f) below and except an electron microscope);

(e) industrial radiography

(f) industrial irradiation

(g) any practice involving a high-activity sealed source (other than one within sub-paragraph (e) or (f) above);

(h) the operation, decommissioning or closure of any facility for the long-term storage or disposal of radioactive waste (including facilities managing radioactive waste for this purpose) but not any such facility situated on a site licensed under section 1 of the Nuclear Installations Act 1965

(i) practices discharging significant amounts of radioactive

*Note that although (b) 'the exploitation and closure of uranium mines' exists in IRR17, it will not appear in the consent process as the UK does not undertake such work.

Note in the following examples we have not considered requirements under the environmental legislation for the UK (this is devolved to the administrations). If you would like to consider this legislation then please consider the following Ionactive resource: UK Environmental Permitting Regulations (radioactive material and waste) - will open in a new tab.

Consents - choose carefully (and note certain anomalies)

The following examples are obvious, but consider them carefully.

  1. Whilst you may have HASS (High Activity Sealed Sources) on site, if your only work is industrial radiography then your consent is for industrial radiography (not HASS).
  2. If you operate an accelerator and you only undertake work involving radiotherapy of patients, then you have an accelerator consent, but if you instead use that equipment only for industrial irradiation then you have an industrial irradiation consent.
  3. If you have a bench top cabinet x-ray unit (e.g 180 kV, 10mA) which you use to sterilise items (e.g. agar gels in a research company), then you need a consent (industrial irradiation), regardless of the fact that very similar units might be used for screening (e.g. for security), and they would only require a registration.

The above is obvious, but not without some level of head scratching. Surely the risks posed by example (3) above are the same? The only difference is the type of work being performed (one a specified practice, the other a certain practice).

A consent (or a registration) for the exact same pulsed x-ray unit?

Consider a 160 kV 5mA portable pulsed x-ray generator (not an accelerator). If this unit is used to screen a wall for hidden objects (e.g. in security investigations), it requires a registration. However, if the identical unit is placed into a shielded enclosure (where there is operator access to set up the work within), and where the unit is interfaced to door interlocks / warning lights / audible sounders / e-stops / emergency pull cables and is used for industrial radiography, then a consent is required.

Under the three-tier regulatory approach, it is intended that consent is for the higher risk practices (such as industrial radiography). In this example, the security screening could take place in a public place / railway station / hotel room (or wherever UK intelligence units wish to operate) - and all this work is under a registration. Whilst the surveillance screening can be conducted safely following well developed procedures (and Ionactive has worked with **** to achieve this), it could be that risk of unplanned exposures is greater then for the enclosure industrial radiography. Ionactive concedes that no regulatory approach will be perfect without anomalies, but we think this is a striking departure from regulatory intent!

Operation of an accelerator (nominally 10MV and above)

In this example we are considering a linear accelerator which is being operated at an energy of at least 10 MV. 10 MV is considered the point where neutrons are produced, these generally being adventitious and therefore generally of no use. [For the physicists reading this, certain reaction cross sections can produce neutrons at lower acceleration energies, but still generally above 8 MV. From a radiation protection perspective, below 10MV neutrons are generally not considered an issue as the photon radiation shielding, or mitigation in walls and mazes, will also deal with the neutrons (and any neutron -> gamma photon reactions)].

This example could also be attributed to other accelerator types including cyclotrons, but in this case careful consideration of the specified practice needs to be considered to ensure the correct one is chosen. Also note that a linear accelerator in industrial irradiation (commonly known as an e-beam) will be under an industrial irradiation consent, but the issues described here could still be possible.

The production of neutrons in this example can lead to neutron activation products. These products vary, some short lived examples are shown below.

  • Al-28 via reaction Al-27 (n,γ) Al-28, beta emitter (with a 1.78 MeV photon), with a half life of 2.3 minutes.
  • Cu-62 via reaction Cu-63 (γ,n) Cu-62, positron emitter (with 0.511 MeV photons), with half life of 9.7 minutes.
  • Mn-56 via reaction Mn-55 (n,γ) Mn-56, beta emitter (with a 0.85 MeV photon), with a half life of 2.6 hours.
  • W-187 via reaction W-186 (n,γ) W-187, beta emitter (with a 0.48/0.69 MeV photon), with a half life of 23.9 hours.

The examples above are for illustration only, the actual neutron activation products will depend on the energy of the accelerator and the component elemental composition which make up the accelerator (and fittings / walls etc).

Some longer lived neutron activation products could include for example.

  • Mn-54 electron capture (with a 0.83 MeV photon), with a half life of 312 days.
  • Co-60 beta emitter (with 1.1/1.3 MeV photon), with a half life of 5.2 years.
  • Ta-182 positron emitter (with a 0.511 MeV photon), with a half life of 115 days.
  • W-181 electron capture (with a 0.057 MeV photon), with a half life of 121 days.

You get the picture, running the accelerator at 10MV or above will produce neutron activation products. The production of adventitious radioactive material from the operation of an accelerator will create an additional radiation protection hazard once the accelerator has been switched off. Merely removing the electrical supply does not mitigate all potential radiation hazards. Dose rates post irradiation could be anywhere between 10's -1000's of micro Sv / hour on contact. There will be a hybrid (average) half life of this dose rate (best determined by actual measurement with a dose rate monitor).

So, in many cases, it could be said that the dominant radiation hazard is NOT created by running the accelerator (since personnel are outside the shielding, unless they are the patient which is then not occupational exposure). The highest occupational exposure dose rates may actually be from the neutron activation products, when access is made into the accelerator shielded area (for setup, repair, service, dealing with a patient).

  • It is absolutely the case that radiation protection from neutron activation products should be an integral part of the procedures for running the accelerator, in compliance with the consent for operation of an accelerator. That said, at this point - no registration is required for working with artificial radioactive materials. The reasoning is that neutron activation is an integral part of working with an accelerator at higher energies. [Note: you may well have a registration for work with artificial radionuclides anyway, due to other work you do. However, the point of this article is not to assume that this is the case, but instead determine what you need for the specific use of accelerators in this example].

What work might you do, related to the activated material, where no registration is required (i.e. all covered within the consent)?

  • Maintenance work on the activated components.
  • Removal of the activated components for replacement (and subsequent storage) - on the basis that the component is not 'waste' (there is a potential crossover here with environmental legislation). So the component still has to be useful.
  • Training on the accelerator which incorporates neutron activated components.

All of the above can be classed as 'operation of an accelerator', and no registration is required.

However: if the activated component is removed from the accelerator and removed from site (either as radioactive material or radioactive waste) then a registration is required. This can no longer be claimed as acceleration operations, and a registration for work with artificial radionuclides will be required (which will also deal with the transport of radioactive materials).

Industrial radiography- do we ever need a registration?

Industrial radiography could use x-ray generators (including accelerators), or HASS (high activity sealed sources). Regardless of ionising radiation source type, it is a specified practice (Industrial radiography) and therefore the actual source type is irrelevant.

Typical radioactive sources used in industrial radiography would include Ir-192 and Se-75, both at activities of 370 GBq and above. These are HASS sources, and this does matter when considering environmental permits (which we are not discussing in this blog article), but does not matter with respect to the specified practice of 'Industrial radiography' - which does not specify the type of ionising radiation source being used.

Way back, a HASS source would remain a HASS source until it reached an exemption level (this being significantly lower than the HASS designation level). That has now changed (via Council Directive 2013/59/EURATOM & at IAEA level) which means that a HASS source stops being HASS once activity falls below the HASS designation level.

So for Ir-192 and Se-75, the HASS threshold level are as follows:

Ir-192 - 80 GBq

Se-75 - 200 GBq

It is common practice for those in the industrial radiography sector to exchange sources long before they drop below the HASS threshold. But just suppose one or more sources DID drop below the HASS threshold (i.e. they are no longer HASS sources). What is the status of the consent and do they need a registration?

Nothing happens and they do NOT need a registration. The status of the sources (i.e. HASS or non-HASS) is irrelevant , since the consent is for industrial radiography (and this consent does not consider the nature of the source of radiation).

We have HASS sources - do we need to consider a registration?

Consider a company which has a number of calibrator facilities for exposing radiation monitors to radiation fields. The company is likely to have a range of sources (probably at consent and registration level). For the purposes of this example we will assume they only have a consent for HASS (noting that Industrial Irradiation is not the same as calibration). The sources they have on site are as follows:

  1. Cs-137 - 20 TBq (reference date is 1975)
  2. Cs-137 - 200 GBq (reference date is 1988)
  3. Co-60 - 300 GBq (reference date is 1995)
  4. Co-60 - 1.5 TBq (reference date is 2001)
  5. Am-241 - 95 GBq (reference data is 1981)

At the reference date activity, all the above sources are HASS, the thresholds are Cs-137 (100 GBq), Co-60 (30 GBq) and Am-241 (60 GBq).

This blog article was released on the 31 July 2023, so let's decay correct to this date and look at the activity now (we know that there is little point with Am-241, but just for fun!!). For this calculation we will assume all the sources reference dates are 1 January 19##. We therefore have the following:

  1. Cs-137 - 9.78 TBq (still HASS)
  2. Cs-137 - 88 GBq (not HASS)
  3. Co-60 - 6.98 GBq (not HASS)
  4. Co-60 - 76.9 GBq (still HASS)
  5. Am-241 - 88.72 GBq (still HASS)

So source 2 (Cs-137, 88 GBq) and source 3 (Co-60, 6.98 GBq) are not HASS sources and are not covered under a consent. From a radiation safety perspective we feel that this makes little difference practically, since both sources still have significant activity and unshielded dose rates at 1m would still be high (6.7 mSv/h for the Cs-137 source, and 2.1 mSv/h for the Co-60 source). So their continued management under the HASS procedures for radiation safety are sensible and practical.

However, from a regulatory perspective, if you do not have a registration for these two non-HASS sources you are not complying with IRR17. As we have said earlier, it is likely (probable?) that a registration will already exist for non-HASS sources - but do not assume this is the case!

Where else could this potentially be an issue?

It is possible that shorter half life radionuclides might be an issue. Take for example the use of Ir-192 in Brachytherapy (a form of radiotherapy where the source is placed directly into the body via an automated after-loader). The HASS threshold for Ir-192 is 80 GBq. A fresh source delivered to a hospital might have an activity of around 400 GBq. The half life of Ir-192 is 74 days, and the hospital would aim be to replace the source within 1 half-life (broadly speaking, half the activity would lead to a doubling of the treatment time). The exchange takes place between the hospital and a licensed courier (generally a fresh source arrives, and the spent source is returned to the source supplier).

Suppose there is a delay (for some reason) and the spent source cannot leave site any time soon. We can calculate the time required to reach the Ir-192 HASS source threshold which is 171 days. Holding this source any longer on site means it is then no longer HASS, and would need to be held under a registration (the hospital most likely already has this for other sources).

Also note that the licensed courier removing the source would need to transport the source under a registration and not a consent, if they only had a consent they would not be complying with IRR17.

So as has been said before, you are probably OK. Perhaps most HASS source holders have registrations for work with artificial radioactive material anyway? Do they (?), read on!

We have a single HASS source (industrial gauge) and a radiation monitor check source

In this next example we have a company based in England with a single HASS source (Am-241, 100 GBq). The HASS source is used in a gauge which measures the thickness of various coatings which are being applied to a backing substrate. The gauge is built into one end of a coating plant and has a motorised shutter which is connected to a safety circuit and active signage (which denotes if the shutter is open or closed). They correctly have a HASS consent in place for this work.

During maintenance the engineer closes down the coating plant, and the interlock arrangement ensures that the source shutter is closed - this provides sufficient shielding to reduce dose rates in the working area down to < 1 micro Sv/h. During a risk assessment the company determines what the dose rate would be if the shutter failed to close, and if this was not noticed by the engineer. They calculate that the dose rate would be 39 mSv/h at 10cm from the shutter, and 360 micro Sv/h at 1m in the general working area. They decide to buy a radiation monitor so that the engineer can verify that the shutter has closed (despite the control systems denoting it is closed).

They feel this is a good ALARP improvement and purchase a radiation dose rate monitor, and a 3 MBq Cs-137 test source (they note the instrument response for Am-241 and Cs-137 will be different, but are not concerned since the source is only being used as a functional check, and Cs-137 is cheaper and easier to get hold of). The source and monitor arrive, and with a protocol written the engineer instigates their monthly checks.

The 3 MBq Cs-137 is not a HASS source, and is NOT covered under the HASS consent. If the company has not obtained a registration from HSE to work with this source, they are not complying with IRR17.

A bit of an aside...

The above example is factually correct, if the scenario played out exactly as indicated above. In reality we would hope that a Radiation Protection Adviser (RPA) would be in place to provide the advice they need, and that a registration would have been applied for before the Cs-137 source arrived on site.

Note also that the site will also have a permit from the Environment Agency (EA) to hold the HASS source. That said, the 3 MBq Cs-137 could be held under exemption criteria - such as 'Scope of and exemption from the radioactive substances legislation in England, Wales and Northern Ireland' (opens in a new tab). Therefore care is needed to not confuse the requirement for a registration under IRR17, with the potential exemption offered under UK environmental legislation. Whilst not the subject of this article, feel free to read up more on this using the online Ionactive guidance: UK Environmental Permitting Regulations (radioactive material and waste) (opens in a new tab).

You have a linear accelerator for cargo container screening and an x-ray unit for small package screening

This company has a single linear accelerator (linac) in a large shielded enclosure (6 MV accelerator). Cargo containers are driven into the enclosure, and the driver exits and is directed to a rest area. The linac is mounted on a gantry which moves up and down the container - security screening the content.

The enclosure has all the expected safety systems:

  • e-stops (externally and internally).
  • physical barriers on the entry and exit points.
  • light curtains to stop the beam if somehow someone enters the enclosure.
  • active lights showing linac status (include red flashing x-ray on indicators).
  • CCTV to view the inside of the enclosure.
  • audible indicators to indicate when the linac is about to start, and a diverse and distinctly different indication when x-rays are being generated.
  • Interlocks on the rest room door (linac will terminate x-rays if this door is opened by the container driver during screening).
  • detailed radiation risk assessment, local rules and contingency arrangements.

As expected, a consent is required for the above work (operation of an accelerator).

The company has a small office block beside the linac enclosure. In the front office is small cabinet x-ray system (160 kV, 1mA) which is used for screening small packages. It has an interlocked door to gain access to the screening areas (there are no open ports or leaded curtains on this particular model). When the unit is producing x-rays there is no access into the screening area, this is protected by two independent safety interlocks on the door. In addition, the door is also mechanically held closed by a magnetic lock which is energised before x-ray production can commence. As expected there are proportional local rules and a risk assessment for this unit.

Despite the significant compliance issues and engineering challenges to be addressed in order to obtain a consent to operate the linac, this company must have a registration to work with the small x-ray unit. Whilst the safety arrangements for the linac can also address working with the small x-ray unit, no credit can be gained from having the consent in place, only a registration will suffice.

You have a Co-60 system for performing stereotactic radiosurgery. It uses an x-ray positioning system.

[In this article we have made a conscious decision not to show pictures or mentioned specific equipment, manufacturers or users. That said, if you know about stereotactic radiosurgery you will know what this is.]

For this example we will assume a small private practice which has been set up on an industrial estate and a purpose made bunker and building has been constructed to house the stereotactic radiosurgery unit (SRU). The SRU contains Co-60 sources in the 100's of TBq range. Each source considered in isolation is a HASS source (HASS threshold for Co-60 is 30 GBq).

Mounted on the side of the SRU is a CBCT x-ray system. This system is used for positioning and confirmation purposes - an arm rotates around the patients head forming an image. When everything is confirmed a treatment can be made by the patient couch being moved towards the unit such that the patients head enters the treatment zone of the SRU. When treatment starts many single beamlets of Co-60 radiation are collimated and can be formed into a single point where radiosurgery of the brain and neck tales place.

Note there is no consent (specified practice) for radiotherapy / radiosurgery etc. With respect to the SRU the only consent available is work with HASS sources. Therefore, as far as the consent is concerned it has no idea how or why the sources are being used. Clearly the CBCT is an integral part of the SRU system - you would not use the Co-60 sources for treatment, without using the CBCT x-ray for positioning. However, as far as the consent is concerned there is no connection between the use of HASS sources and use of a CBCT x-ray system. For this reason the following is required:

  • A consent for work with HASS sources.
  • A registration for work with x-ray generators

We know that in most (all?) cases the SRU system is probably going to be used in a large hospital where it is likely a HASS consent and registration (for x-ray systems) are in place. This is why we used a private practice to highlight that no assumption should be made when considering what consents or registrations might be required. Reliance on 'we have everything so we will be ok' should not come into it.

Also - consider handing the SRU system over to a service contractor for service / repair / calibration etc. Does the service contactor have a HASS consent and registration for work with x-ray generators?

Is your service contactor from overseas (outside the UK with no legal representation in the UK)?

This is simply a quick advert for a recent blog article released by Ionactive: Non-UK companies working with ionising radiation in the UK (opens in a new tab). It is relevant - even if the subject of consents and registrations in this blog article has been obvious to you, you need to consider the same requirements for any overseas contractor you invite into the UK to work on your systems. Do they have the required consents and registrations from HSE?

Closing thoughts

If you have got to this point (!), we hope you have found this blog article of some interest.

As already suggested, it is likely that for most of the scenarios above all the required consents and registrations will be in place. However, as also suggested in this article, this might be by default rather than by design.

Mark Ramsay

Radiation Protection Adviser
Chartered Radiation Protection Professional (CRadP)

(c) July 2023

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