People often ask these radiation protection questions

Set of radiation protection related questions and answers often asked by RPS / RPO delegates and by people via email or social media

  • Can I become contaminated by radiation?
  • Can radiation be passed from person to person?
  • What materials can block ionising radiation?
  • What are the four main practical principles of radiation protection?
  • What is radiation Skyshine - and does it matter to me?
  • What is the difference between sealed and unsealed radioactive source?
  • What is RPS training?

Can I become contaminated by radiation?


'Radiation' cannot be passed from person to person, just as visible light cannot be passed from person to person.

However, radioactive material (which emits radiation) can pass between individuals in the form of radioactive contamination. Radioactive contamination is a physical substance - and like all substances can move around in the environment. Therefore when considering if it is possible to be contaminated with radioactive material consideration has to be given to its physical properties and environmental factors around it (including possible exposure pathways)

Often in the media the word 'radiation' is used quite carelessly. This extends to ionising and non-ionising radiation which is why mobile phone (e.g. 5G) radiation is often associated with nuclear processes (it is not). So here we are talking about radioactive material which emits ionising radiation.

Can radiation be passed from person to person?

This question is often asked but needs some clarification before providing an answer. Radiation cannot be passed from person to person, just as visible light cannot be passed from person to person. However, if you mean radioactive material (which emits radiation) then its possible to pass this between individuals. Radioactive material is a physical substance which may take the form of a solid, liquid or gas. Therefore, if the radioactive material is mobile in the environment then it can be passed from person to person.

What materials can block ionising radiation?

The type of material depends on the type of ionising radiation in question.

Alpha Particles - single sheet of paper, the outer dead layer of skin of your body, clothing

Beta Particles - depends in energy of beta particle, but 12mm of a low density material like perspex or plastic will stop all betas

Gamma Ray / X-ray - shielding performance depends on energy of the radiation for a given thickness and density. Higher density shielding such as lead / tungsten will provide the best shielding performance for the least thickness. If space is of little concern high density concrete, normal concrete or even water can be used (but these shields will be thicker).

What are the four main practical principles of radiation protection?

The following four principles are valid for ionising radiation (although not all will apply for individual cases as this will depend on the type of radiation source involved).

Time - Minimise the time of exposure.

Distance - Maximise the distance from the source of radiation.

Shielding - Use radiation shielding where practicable.

Containment - For unsealed radioactive materials use containment to minimise risk of contamination spread and avoid inhalation of ingestion hazards.

What is radiation Skyshine - and does it matter to me?

Radiation skyshine is where radiation (predominately gamma or x-rays) scatter within air (and other objects) above a facility which is either open topped (no shielding) or has reduced shielding. Radiation from the bottom of the facility will scatter upwards to the top of the facility, and some of this will then scatter downwards towards the ground - the other side of the facility shielding. It may be that direct measurements from the source of radiation through the shield are negligible. However, as you move away from the facility a peak dose rate will be measured some distance from the shielding (maximum skyshine) before reducing with further distance from the facility. It matters to you as many have ignored this phenomenon and only discovered higher dose rates some distance from the facility many months later.

A more rigorous explanation of Skyshine can be found here: Skyshine – radiation scattering around and over shielding.

What is the difference between sealed and unsealed radioactive source?

Sealed radioactive material is that which is contained or encapsulated in some way so that the radioactive material cannot move within the environment around it. This is sometimes known as a sealed or closed radioactive source. Such sources can only present an external radiation hazard, walking away from the source will reduced radiation exposure to negligible levels. Unsealed radioactive material (or source) is where the material is not contained, and depending on circumstances, can move around the environment. An example could be a radioactive liquid that has been spilled from an open container. This unsealed material is called contamination and could be taken into the body by ingestion, inhalation or through cuts in the skin. Walking away from the container will not necessarily reduce the radiation exposure hazard to zero since this person may already be contaminated.

What is RPS training?

What is RPS training?

The term RPS stands for Radiation Protection Supervisor (RPS). The RPS is a position recognised by the UK Ionising Radiations Regulations 2017 (IRR17). It is required in most cases where an employer wishes to work with ionising radiation (e.g. x-ray systems, radioactive sources and similar).

In order for the employer to appoint one or more of their employees as an RPS, the employee should attend an RPS training course. Usually the RPS course is provided outside the company (i.e. only the nuclear industry, other very large users of radiation and perhaps some hospitals provide their own in-house courses). Pre-Covid RPS courses would normally be held at a training venue arranged by the training provider in the form of public face-2-face training. During the pandemic many courses have been run online using Teams or similar. Ionactive took a different approach and created a popular multimedia online RPS training course.

Attending a RPS training course does not make that individual an RPS. To become an RPS the employee needs to attend a suitable training course and then be appointed in writing by their manager or other suitable person. The type of training and number of RPS positions required will depend on the nature of the work with ionising radiation and usually the employer would consult with a Radiation Protection Adviser to determine what is required.

In some cases attendees of RPS training are not appointed into post after completion of the course. This is usually due to the employer wishing certain employees to be trained to a recognised standard in radiation safety, but without the need to then take on a RPS position formally.

What happens at an RPS training course?

At the time of writing the exact nature of RPS training may vary if it is being taken online, or live via Teams / Zoom or similar. A good RPS training course will have a little maths and physics - this is unavoidable. However, this is at a level which does not require any previous formal education in either subject. It is more important that the training delegate is interested and willing to take the training rather than come prepared with formal qualifications. The course will also contain some elements of health and safety law including a summary of the Ionising Radiations Regulations 2017 (IRR17). A course will generally cover some of the following matters:

  • Basic introduction to ionising radiations and their biological effects
  • Units used in radiation protection (e.g. for dose and radioactivity)
  • The basic protection principles (e.g. time, distance, shielding and potentially containment)
  • Contingency arrangements (what to do when things go wrong)
  • Radiation monitoring and dosimetry (i.e. workplace and personal monitoring)
  • The content of Local Rules (the 'do' and 'do not').
  • The role of the RPA
  • The role of the RPS

Suitable courses will also usually include a small test so that an 'achievement' certificate can be awarded (this more valuable to the delegate and employer than an 'attendance' certificate.

Whereas some training providers will offer 'sector' (or source) specific RPS training (e.g. x-ray or unsealed radioactive materials), from the very beginning Ionactive has provide courses that cover all areas of ionising radiation use. Whilst the delegate usually ends up with more knowledge than they strictly need, it allows them to consider their own radiation source use in context with other uses (and this helps in the appreciation of radiation risk).

RPS course providers including Ionactive will also often provide onsite bespoke RPS training where enough delegates all need training at once.