The overarching duty in the Ionising Radiations Regulations (NI) 2017 (IRRNI2017) is to restrict exposure so far as is reasonably practicable (IRRNI2017) regulation 8(1)).
The radiation employer should, in consultation with their Radiation Protection Adviser, carry out an assessment of the risk associated with the proposed work in accordance with regulation 7 of IRRNI2017 or regulation 3 of the Management of Health and Safety at Work Regulations (NI) 2000 (MHSWR). One of the outputs of the risk assessment is to identify if individuals should be classified. If the assessment of potential exposure shows that restriction of their doses below the levels specified in regulation 18(2) IRRNI2017 (that is, employees are likely to receive an effective dose in excess of 6mSv per year or an equivalent dose in excess of 3/10ths of any relevant dose limit) could not reasonably be ensured even with written arrangements, people working in the area should be classified.
If an assessment of the potential exposure shows that the work could be done by employees who are not classified persons, HSE would normally expect entry into controlled areas to be allowed under suitable written arrangements (local rules). Entry under suitable written arrangements should not involve a system of work sharing simply to avoid classifying the people working in the controlled area.
Employees who have been designated as classified will be made subject to medical surveillance and have their doses appropriately assessed and recorded.
You will need an appointed doctor or employment medical adviser if your employees are subject to medical surveillance under the Ionising Radiations Regulations (NI) 2017. The appointed doctor is responsible for checking whether employees are medically fit to work with ionising radiation.