Revised: September 2022
1. Introduction
During construction and renovation projects an inspection of concrete, pipes, rebars, post-tension cables, etc., may be necessary. Also, this type of work may be necessary to identify hidden reinforcing steel bars, plumbing, or conduit within the concrete. Three main methods are used Industrial Radiography (IR), Ground Penetrating Radar (GPR) and Ultrasound (US).
Infrared scanning of electrical components and systems is part of the maintenance program of the electrical equipment. During this procedure, no radiation is emitted by the scanning equipment.
2. Industrial Radiography (IR)
Industrial radiography is performed by using ionizing radiation (gamma-ray generated by a high-intensity gamma radiation source or X-ray generated by a radioactive source or by an x-ray machine).
Fig. 1 – Examples of Industrial Radiography devices
The radiation sent by the IR device penetrates the material and is absorbed in different degrees depending on the density of the material. An image is obtained and analysed to determine the existence of holes, cracks, defects, etc. The main advantage of this method is a clear picture of the structure being inspected. The main disadvantage is the need to evacuate persons in a relatively large area to prevent radiation exposure. Due to this disadvantage, if the area cannot be evacuated (e.g.: hospitals), a Ground Penetrating Radar is used.
When a clear image of the inspected structure is required, and the surrounding area can be evacuated, the Industrial Radiography method is used. All Industrial Radiography scannings need a permit approved by the U of T Radiation Protection Service.
3. Ground Penetrating Radar (GPR)
The GPR system uses non-ionizing radiation (Radio Frequency) to perform similar inspections on concrete structures.
Fig. 2 – Examples of Ground Penetrating Radar devices
The radio frequency used by the GPR is reflected differently by the different parts of the structure being investigated. The reflected radiation is measured with a scanning device. This reflected radio frequency is not hazardous to the human body, therefore the GPR method can be used without restrictions.
4. UltraSound (US)
More recently a new technique based on ultrasound is being used
Fig. 3 – Examples of Ultrasound devices used for concrete scanning
The UltraSound and Ground Penetrating Radar methods have similar advantages and disadvantages.
5. Infrared Scanning of Electrical Equipment
During this scanning process, the equipment used measures the infrared radiation (heat) emitted by the electrical components. Since no radiation is emitted for the scanning process, the procedure does not pose a radiation hazard.
Fig 4 – Infrared Scanning of the electrical equipment
Since the Infrared Scanning of electrical equipment, the Ground Penetrating Radar and UltraSound methods do not pose a hazard to the persons, no EHS permit is required to perform these scanning processes.
6. Industrial Radiography Permit System
Every radiographer must have a Canadian Nuclear Safety (CNSC) licence to possess and use radioactive sources. To ensure the safety of the University’s students, faculty, staff and the public, every IR project must be approved by the U of T Radiation Protection Service (RPS). An industrial radiography permit is issued for each project.
The radiography source permit system ensures that:
- the radiography source and user are licenced or otherwise approved by the regulatory authorities;
- the potential hazards of exposure to these sources have been identified and assessed;
- that necessary safety measures are in place;
- that workers, students, and staff are aware of the safety procedures to follow during such testing.
To apply for an Industrial Radiography permit please submit the following materials at least five (5) days before the date of the proposed project:
- A completed IR permit application form, Industrial-Radiography-Form.pdf.
- Contractor’s CNSC license for the radiation source and technique being used for IR
- A copy of the communication submitted to all potential stakeholders that are involved in a potential exposure
- A site plan indicating the area where the work will be conducted and indicating potential exposure areas
The permit must be authorized by the Design and Construction Project Manager or Building Property Manager responsible for the work, indicating that this work will be done following the University’s industrial radiography permit system. Following authorization by the Project Manager, the permit must be signed by the radiographer and sent to daniel.cardenas@utoronto.ca.
After approval by the Radiation Protection Service, the permit having a unique permit number will be sent to the University Project/Property Manager. The University Project/Property Manager must keep the permit on file for three years after completion of the project.