Purpose

The purpose of this procedure is to ensure the correct use of radioactive sources, and to ensure that radiation protection efforts at NTNU comply with regulatory requirements and safeguard the safety of employees, students, and others at NTNU.

Scope and foundation

This procedure applies to all units, employees, and students at units using radioactive sources owned by NTNU. The procedure is a measure to reduce the risk associated with working with radioactive sources.

This procedure is governed by the Guidelines for radiation protection and the use of radiation sources.

Definition

Radioactive sources

Radioactive sources emit alfa-, beta- or gamma radiation.

• Sealed radioactive source: A radioactive material that is encapsulated to prevent the release and spread of radioactive substances into the environment.
• Open radioactive source: All radioactive sources that are not encapsulated are considered open sources. The use of open sources involves direct access to the radioactive material.

Work with radioactive sources shall be conducted in a manner that ensures exposure to users and the environment is kept as low as reasonably achievable, with minimal risk of accidents.

Refer also to the glossary at the end of the procedure.

Responsibility

Line manager

The line manager holds the overall responsibility for  radiation protection at the unit. The line manager shall perform the tasks described in the Guideline for radiation protection and use of radiation sources.

The line manager shall approve Class C isotope laboratories.

Procedure for work with radioactive sources

Local radiation protection coordinator

The local radiation protection coordinator shall perform the tasks described in the Guideline for radiation protection and use of radiation sources.

In addition, when working with radioactive sources, the local radiation protection coordinator shall ensure the following:

• Maintain an overview of isotope laboratories and how the laboratories are to be used.
• Report any changes in the use of isotope laboratories to the central radiation protection coordinator once a year.
• Notify the central radiation protection coordinator of the use of new radionuclides that have not previously been approved for use in Class C isotope laboratories.
• Submit applications for the use of new radionuclides that have not previously been approved for use in Class B isotope laboratories to the central radiation protection coordinator, who will forward the application to the Norwegian Radiation and Nuclear Safety Authority (DSA).
• Manage the use of personal dosimeters and maintain user registration within the unit.

Academic supervisor

The Academic supervisor shall perform the tasks described in the Guideline for radiation protection and use of radiation sources.

In addition, when working with radioactive sources, the academic supervisor shall ensure the following:

• Conduct a risk assessment. For the use of open radioactive sources: use the checklist and section 2.5.1 in the Guide for use of open radioactive sources in laboratories as a tool.
• Label the workplace, sources, and equipment. This may be done in collaboration with the local radiation protection coordinator.
• Assess the need for personal dosimeters.
• Ensure proper storage of radioactive sources.
• Clarify arrangements for return or disposal before the unit acquires sealed radioactive sources.
• Sealing in accordance with ISO 2919 Sealed radioactive sources – classification. The sealing must prevent leakage during normal use and in the event of accidents.
• Conduct regular inspection and maintenance of equipment containing sealed radioactive sources. This includes checking label legibility, the function of closure mechanisms, measuring radiation levels around the equipment, etc.
• Ensure that the unit has a detailed description of work involving open radioactive sources. The work procedure should be developed by a competent person familiar with the work, in collaboration with the local radiation protection coordinator. When drafting a work procedure, consider factors such as:

1. Users’ experience

2. Laboratory equipment

3. Availability of immediate assistance in case of an incident

The work procedure should include information such as:

• Which open sources will be used
• Permitted activity levels
• How the sources will be stored
• Measurement and protective equipment to be used, such as gloves, bench paper, radiation monitors, shields, lead, and personal dosimeters
• Regular contamination checks and radiation level measurements in the workplace. The need for contamination control should be assessed based on laboratory usage frequency, the amount of activity handled, and the likelihood of contamination. The required type of control depends on the source.
• Waste handling

Further details about work procedures, contamination control, and fume cupboards can be found in section 2.4.4 of the Guide for use of open radioactive sources in laboratories.

• Ensure that users are trained in the work procedure. When radioactive materials are introduced, the work can then be conducted efficiently and with minimal risk of incidents.
• Ensure that employees, students, and others involved receive locally adapted training in:

1. Locally developed guidelines and manuals

2. Use of measurement and protective equipment

3. Waste management

4. Local emergency response plans

Further information about training is available in section 2.4.1 of the Guide for Use of Open Radioactive Sources in Laboratories.

• Ensure that work with volatile radioactive sources always takes place in a suitable fume cupboard or glove box.

Central radiation protection coordinato

The central radiation protection coordinator shall carry out the tasks described in the Guideline for radiation protection and use of radiation sources.

In addition, when radioactive sources are used, the central radiation protection coordinator shall ensure the following:

• Forward applications for the use of new radionuclides in Class B isotope laboratories.
• Ensure that NTNU at all times holds the necessary approvals for work involving radioactive sources in accordance with section9 of the Norwegian radiation protection regulations (Strålevernforskriften).

Users of radioactive sources

Users shall carry out the tasks described in the Guideline for Radiation Protection and Use of Radiation Sources.

Safety and technical requirements

Work involving open radioactive sources with activity levels below the exemption limits specified in the annex to the radiation protection regulations (Strålevernforskriften) may be conducted in areas that are not designated as Class B or Class C isotope laboratories. All other work with open radioactive sources shall be performed in isotope laboratories according to the following criteria:

Permitted in Class B Isotope Laboratories

• Standard chemical work: Up to 10⁴ × the exemption limit
• Withdrawal of stock solutions and preparation of dilutions: Up to 10⁵ × the exemption limit
• High-risk activities, work with dry substances: Up to 10³ × the exemption limit
• Work with tritiated thymidine (³H-thymidine): Activity limits in section 27 of the radiation protection regulations reduced by a factor of 10

Permitted in Class C Isotope Laboratories

• Standard chemical work: Up to 10 × the exemption limit
• Withdrawal of stock solutions and preparation of dilutions: Up to 100 × the exemption limit
• High-risk activities, work with dry substances: Up to the exemption limit
• Work with tritiated thymidine (³H-thymidine): Activity limits in section 27 of the radiation protection regulations reduced by a factor of 10

Pregnancy and work with radioactive sources

Occupationally exposed pregnant workers:

The dose to the fetus must not exceed 1 mSv for the remainder of the pregnancy, i.e., after the pregnancy is known. If you are pregnant, you must inform your employer as soon as possible. The expected dose to the fetus for the rest of the pregnancy must be assessed, and necessary protective measures shall be implemented.

The Norwegian radiation and nuclear safety authority (DSA) provides the following guidance:

• Dose is confidently assessed to be less than 1 mSv: The pregnant worker may continue with her usual work tasks without additional precautions.
• Dose is assumed to be less than 1 mSv: The pregnant worker may continue with her usual work tasks, possibly with additional precautions to reduce radiation exposure.
• Dose is assumed to exceed 1 mSv: The pregnant worker must be reassigned to other tasks with lower potential for exposure, or to work where there is no exposure to ionising radiation.

Example: The dose to the fetus from working with RIA kits is confidently assessed to be less than 1 mSv.

The pregnant worker’s own perception of the situation should also be taken into account. If requested, the employer shall, as far as practically possible, offer alternative tasks or reassignment.

For more information on pregnancy and work with open radioactive sources, see section 4.2 of the guide for use of open radioactive sources in laboratories.

Protective equipment, shielding, and safety devices

Necessary shielding, technical safety systems, and personal protective equipment must be available to ensure that the risk of incidents and radiation exposure to users and the surrounding environment is kept as low as reasonably achievable.

The unit must have access to radiation monitors for both contamination checks and dose mapping.

For more detailed information on shielding, safety requirements, and a comprehensive overview of methods and equipment, see section 3.4 of the guide for use of open radioactive sources in laboratories.

Labelling and classification of the workplace

In all areas where work is conducted: Display the standard radiation symbol (e.g., tape or sign) for radioactive materials when activity levels exceed exemption limits. Labelling must be done in accordance with Chapter 5 of the workplace regulations. The standard symbol is also defined in NS 1029 Symbol for Ionising Radiation.

If the risk assessment indicates that the workplace should be classified as a controlled area or a supervised area, this must be clearly marked on the door or at the entrance. The signage must also include an explanation of what the terms mean.

A room card must be posted. It shall indicate whether the area is classified as “controlled” or “supervised” and include information about the location of radiation sources and the associated risks. In rooms where only part of the space is designated for work with radioactive sources, this must be clearly specified on the room card.

Labelling of sources

Radioactive sources must be labelled with the standard symbol for ionising radiation. The standard symbol is defined in NS 1029 symbol for ionising radiation. The label must include information such as the type of source, serial number or other unique identifiers, and the activity on a specific date.

Labelling of equipment

All equipment that may be contaminated must be marked with the standard radiation warning symbol. All glassware or containers holding radioactive material (substances, solutions, or waste) must be labelled with the standard radiation warning symbol, as well as information about the type of radionuclide and the activity level on a specific date.

Physical security

The number of individuals who may come into contact with radioactive materials must be kept to a minimum. The unit must maintain an up-to-date list of these individuals by name. In addition, the use of radioactive sources must be organised in such a way that the risk of theft and sabotage is minimised as far as reasonably possible. See also the section on physical security of radiation sources in the Guideline for radiation protection and use of radiation sources.

Rooms or areas containing radioactive sources must have the following:

• Access control to prevent unauthorised persons from entering areas where they may be exposed to radiation or could commit theft or sabotage. If radioactive sources are stored in rooms without access control, they must be under constant supervision. Storage in rooms with access restrictions does not require locked cabinets or continuous supervision.
• Warning signs, preferably including basic information about the radiation and any mandatory protective equipment.
• Room cards listing the radioactive sources present.
• Technical measures that make theft and sabotage more difficult (e.g., fixed mounting of equipment, secure storage cabinets, etc.).
• Technical safeguards to protect radioactive sources from fire, water damage, or other hazards.

Transport, storage, and handling

Transport

Refer to the Norwegian Radiation Protection Authority’s booklet no. 26: Transport of radioactive material in excepted packages. These regulations also apply when radioactive material is contained in, or is a component of, items such as watches or instruments.

Storage

Radioactive sources must be stored in accordance with section 25 of the radiation protection regulations. This includes all forms of storage—from the time the source is acquired until it is disposed of.

An entire refrigerator or the specific shelf where radioactive solutions are kept is considered a storage area. The same applies to cold rooms, freezers, or similar storage environments.

Handling

Radioactive waste from the use of open radioactive sources and sealed sources that are permanently taken out of use must be handled in a way that does not pose a risk to people or the external environment. See the Guideline for radioactive waste for further information.

Dosimetry

According to section 33 of the Norwegian Radiation Protection Regulations, all occupationally exposed workers in Category A, as well as Category B workers who may receive an effective dose exceeding 1 mSv per year, must have their individual radiation exposure determined. Determination of the exposure can be carried out through individual measurements using personal dosimeters or based on individual dose calculations. Category A workers are generally required to wear personal dosimeters. If this is not practically feasible, dose estimation must instead be based on individual calculations.

Students conducting practical work as part of their studies (e.g., in laboratories or during internships in companies) are considered equivalent to employees for radiation protection purposes and must also wear personal dosimeters. NTNU administers dosimeters for students who participate in internships.

Use of a personal dosimeter is not required if the following conditions are met:

• The estimated effective radiation dose to a person is less than 1 mSv per year, or the estimated dose to the hands is less than 50 mSv per year, based on dose rate measurements and actual usage patterns.
• The responsible person performs regular contamination checks of areas and equipment.

Work involving radioactive isotopes must be risk-assessed, including an evaluation of the need for dosimeter use. Each unit may determine whether personal dosimeters or finger dosimeters must always be used when handling certain isotopes. In all cases, individuals must be allowed to use an appropriate dosimeter if they wish. The local radiation protection coordinator typically manages the dosimetry service.

Results from dosimeter readings are submitted to the National Dose Registry maintained by the Norwegian Radiation and Nuclear Safety Authority (DSA). The registry provides a consolidated record of occupational exposure to ionising radiation in Norway, regardless of changes in employer. Individuals, organizations, and the DSA have access to the information in the registry.

NTNU’s dosimetry service providers upload the data to the registry. Employees and students who have used dosimeters, as well as NTNU’s radiation protection coordinators, may access the registry via the national ID portal.

Exposure index

Work involving ionising radiation may require registration in an exposure register. Visit the dedicated Exposure index page for a full overview of the required actions. The register itself is accessible through the chemical substances management.
Log in to the system, click on the symbol for “Exposures” in the left-hand menu.

Glossary

Bq – Becquerel: A unit used to measure the activity (strength) of a radioactive source. It represents the number of atomic nuclei transformations (decays) per second.

Type B Isotope Laboratory: A specially designed laboratory where only open radioactive sources may be used.

Type C Isotope Laboratory: Laboratory area designated for work with open radioactive sources.

Sealed Radioactive Source: A radioactive substance enclosed in a container designed to prevent the release of radioactive material into the environment.

Contaminated: Polluted with radioactive substances.

Controlled area: A workplace must be classified as a controlled area if employees may be exposed to radiation doses exceeding 6 mSv/year, or if the dose to the hands may exceed 150 mSv/year. If physical boundaries are not feasible, the area must be clearly marked or otherwise visibly delineated.

Decay / Transformation: A radioactive transformation in which the nucleus emits radiation and changes into another element. This process is also known as disintegration or decay.

Monitored area: A workplace must be classified as a monitored area if employees may be exposed to radiation doses exceeding 1 mSv/year, or hand doses exceeding 50 mSv/year. Organizations using ionising radiation sources must ensure that radiation use and shielding are arranged such that individuals outside the monitored area are not exposed to more than 1 mSv per year.

Radioactive source: A radiation source containing radioactive material that emits alpha, beta, or gamma radiation.

Exemption limits: Work involving activity levels below the threshold values listed in the annex to the Radiation Protection Regulations may be exempt from certain regulatory requirements. At such levels, the work does not need to take place in an isotope laboratory. Use of multiple nuclides at once must be assessed separately.

Open radioactive sources: Radioactive materials that are not sealed. When handling open sources, direct contact with the radioactive substance is possible.