Ionising radiation

Dose limits and protection principles

Radiation protection is based on three principles: justification (every practice must produce a net benefit that outweighs the detriment), optimization (keeping doses as low as reasonably achievable, the ALARA principle, with dose restrictions), and dose limitation (individual limits that must not be exceeded). Royal Decree 1029/2022 sets an effective dose limit of 20 millisieverts per calendar year for exposed workers, with equivalent dose limits of 20 millisieverts per year for the lens of the eye, 500 for the skin, and 500 for the extremities; reduced limits for trainees and students aged 16 to 18; 1 millisievert per year for the general public; and special protection for pregnant and breastfeeding workers.

Workers exposed to these hazards are classified as Category A when they may receive an effective dose exceeding 6 millisieverts per calendar year or equivalent doses exceeding three-tenths of the limits for the lens of the eye, skin, and extremities, and Category B in all other cases. Work areas are classified as supervised and controlled zones (with subzones of limited stay, regulated stay, and prohibited access), marked with the official trefoil symbol and with restricted access and work procedures.

The holder’s obligations include the prior assessment of working conditions, the classification of areas and workers, the radiological monitoring of the environment, the individual dosimetry of Category A workers through authorized dosimetry services, specific health surveillance by prevention services with the corresponding accreditation, training and information, the recording of doses in the dosimetric history and communication to the National Dosimetric Bank, and the organization of radiological protection through radiological protection technical services or units and supervisors and operators licensed by the Nuclear Safety Council.

Sources of occupational exposure and measures

• Health. Radiodiagnosis, interventional radiology, nuclear medicine and radiotherapy: shielding, collimation, distance, time, aprons and thyroid and lens protectors, personal and area dosimetry, and special control in interventional procedures due to doses to the lens and extremities.
• Industry. Industrial radiography with gamma and X-ray sources, nuclear level, density and thickness gauges, sterilization and analysis: encapsulated sources with shielding, delimitation of zones during exposures, operating and emergency procedures and source control.
• Nuclear and radioactive installations. Authorization regime of Royal Decree 1217/2024, radiological protection plan, monitoring, waste management and emergency plans.
• Radon . Naturally occurring radioactive gas from the ground that accumulates indoors; Royal Decree 1029/2022 establishes a reference level of 300 becquerels per cubic meter for workplaces and requires measurement in the priority action municipalities defined by the Nuclear Safety Council (Instruction IS-47) and in certain workplaces, with ventilation, sealing and occupancy reduction measures when it is exceeded.
• Aircrews. Assessment of exposure to cosmic radiation and organizational measures when the dose may exceed 1 millisievert per year.
• Naturally occurring radioactive materials. Industries with materials of natural origin (phosphates, minerals, ceramics, oil and gas) subject to evaluation and control in accordance with the regulations.
• General measures. Reduction of exposure time, increased distance from the source and shielding, along with facility design, procedures, training and dosimetric and health monitoring.

Organization, surveillance and emergencies

• Radiological protection services and units. Technical organization that advises the owner, with a head of service authorized by the Nuclear Safety Council in the facilities that require it.
• Licenses. Supervisors and operators of radioactive installations licensed by the Nuclear Safety Council and with specific training in radiological protection in radiodiagnosis and other areas.
• Dosimetry. Personal dosimeters for lapel, wrist, ring or lens depending on the exposure, with monthly reading by authorized services and recording in the individual dosimetry history.
• Health surveillance. Specific prior and periodic examinations, fitness assessment and preservation of medical records for the regulatory periods (until the worker reaches 75 years of age and at least 30 years after termination).
• Records and communication. Dose recording, reporting of limit exceedances to the Nuclear Safety Council, investigation of causes and corrective measures.
• Emergencies. Internal emergency plans, control of lost or orphaned sources, and coordination with external plans and authorities.

Organizational application: how to manage radiation protection in the company

1. Identify all sources of ionizing radiation present (equipment, encapsulated sources, radiopharmaceuticals, radon, natural materials) and verify the authorizations and registration of the facility.
2. Carry out the prior assessment of working conditions and classify areas and workers in accordance with Royal Decree 1029/2022, with signage and access control.
3. Organize radiation protection: service or technical unit, licensed supervisors and operators, work and emergency procedures.
4. Implement individual and area dosimetry with authorized services, maintain the dosimetric history and communicate the doses to the National Dosimetric Bank.
5. Ensure specific health surveillance and protection of pregnant and breastfeeding workers, as well as training and information for exposed workers.
6. Measure radon in required workplaces and take action when the reference level is exceeded.
7. Record and periodically review doses, incidents and measures, and coordinate with contractors and external workers who access controlled areas.

Preventive management software allows you to maintain the census of sources and equipment, the classification of zones and workers, the dosimetric and health surveillance records with their retention periods, the licenses and training, and the radon measurements per center.

Limits and common mistakes

1. Treating radiological protection as part of general prevention without applying the specific regulations or the supervision of the Nuclear Safety Council.
2. Failure to properly classify areas and workers, or allowing access to controlled areas without dosimetry or training.
3. Neglecting lens and limb dosimetry in interventional radiology and other tasks with localized doses.
4. Forgetting about radon in workplaces in priority action municipalities and in basements, mines, caves and underground facilities.
5. Failure to guarantee the protection of pregnant or breastfeeding workers after notification of their condition.
6. Retain dosimetric and medical records for periods shorter than those required by regulations.

The detailed obligations are set out in Royal Decree 1029/2022, Royal Decree 1217/2024 and in the instructions and guides of the Nuclear Safety Council; this sheet is for informational purposes.

Regulatory and reference framework

• Royal Decree 1029/2022, of December 20. Regulation on the protection of health against the risks arising from exposure to ionizing radiation.
• Council Directive 2013/59/Euratom . Basic safety standards for protection against the dangers arising from exposure to ionizing radiation.
• Royal Decree 1217/2024, of December 3. Regulation on nuclear and radioactive installations and other activities related to exposure to ionizing radiation.
• Nuclear Safety Council Instruction IS-47 . Municipal areas of priority action against radon and guidelines for measurements in workplaces.
• Nuclear Safety Council . Regulatory body for nuclear safety and radiological protection in Spain.

Law 25/1964 on nuclear energy and Law 15/1980 creating the Nuclear Safety Council constitute the general legal framework; Royal Decree 1085/2009 regulates the installation and use of X-ray equipment for medical diagnostic purposes.