Radiation Safety is the protection of workers
from the harmful effects of radiation.
Industries that produce NORM can concentrate the radioactive materials found in our environment to levels that exceed Canada’s Radiation Protection Regulations. Exposures to radiation cannot be prevented, however they can be controlled. A proper Radiation Safety Program will control both internal and external radiation exposures. Radiation Protection Programs or safe work practices are required by regulations.
In the Oil and Gas Industry we have seen levels as high as 450 µSv/hr on contact of waste and 50 µSv/hr at 1 meter. An incidentally exposed worker could not spend more than 20 hours within 1 meter of the waste without exceeding the regulatory limit for an external exposure. We have also seen waste with activity levels up to 28,600 Bq/g. Inhalation or ingestion (Internal Exposure) of a volume less than the size of the tip of a pencil would exceed regulatory limits.
Implementation of a Radiation Safety Program will ensure workers maintain exposures to levels that are well below regulatory limits and maintained under the principle of ALARA (As Low As Reasonable Achievable). This principle is recognized by all levels of governments and a requirement under the Radiation Protection Regulations. This principle means the following:
“All radiation exposures are considered potentially hazardous to health regardless of any regulatory limit. A regulatory limit is an exposure that should not be exceeded. It is simply not acceptable to just maintain worker exposures to values below regulatory limits. Organizations must maintain exposures as low as reasonable achievable social and economic factors taken into consideration.”
Many organizations have NORM policies and procedures that outline the appropriate PPE to be worn when working with NORM impacted materials or waste. These types of policies only prevent inhalation or ingestion exposures. A detailed Radiation Safety Program will include:
- Identification of who is in charge of overall radiation safety for the organization. This is not necessarily the person on a NORM site but rather the person workers can call to address radiation safety concerns. This person is typically called the corporate Radiation Safety Officer (RSO) and must have extensive knowledge and experience in radiation protection.
- Outlines the corporations requirements on surveys to identify NORM impacted waste and materials as well as monitoring requirements and will include the following:
- Gamma radiation surveys requirements for detection of NORM impacted materials and waste.
- Contamination surveys to identify objects that require cleaning or need to be controlled. These types of surveys prevent NORM accumulations from being spread around a worksite giving potential for workers to ingest.
- Air monitoring requirements to detect levels of radon gas in the work area or low level radioactive dusts (LLRD’s). Health Canada has established maximum concentration limits of radon in air that a workplace cannot exceed. Monitoring for LLRD’s determines the need for respiratory protection and dust control measures. If LLRD’s cannot be eliminated, air monitoring is required to verify the internal exposures of workers in the event of respiratory malfunction.
- Radiation Survey requirements. Radiation surveys are required to verify if external exposures in a work area need to be controlled. Control of these work areas are typically completed by controlling the amount of time workers may spend in that area.
- Identifies how internal exposures will be controlled within the organization. This may include engineered controls at specific sites or administrative controls such as NORM policies, procedures or codes of practice. These policies outline how contamination will be controlled to prevent ingestion such as setting up control area’s and how inhalation will be prevented by dust control measures and appropriate PPE. A control area is an area where exposure to radiation may occur and is identified by signage. Special policy and procedures are required within this area to control radiation exposures.
- Identifies how external Exposures will be controlled within the organization. External exposures cannot be eliminated only controlled as we live in a world where radiation is all around us (i.e. Gamma rays from the sun). External exposures can be controlled from NORM impacted materials or waste through the following means:
- By controlling the amount of time we spend around the NORM impacted materials or waste.
- By keeping our distance from the NORMN impacted material or waste such as putting up fencing and restricting access to NORM impacted areas.
- Shielding the NORM impacted materials or waste to prevent the gamma rays from reaching workers. This method typically is not practical in the oil and gas industry for NORM impacted materials or waste. It is however common with man-made sources where the size of the source is small and can be housed in materials such as a lead lined enclosure.
- Defines record keeping requirements. Exposures to workers are based off yearly exposures. As such records must be maintained from exposures do to daily work activities in order to compile these yearly assessments. A radiation safety program outlines how these records will be maintained to verify worker exposures.
- Defines training requirements for workers.
- Defines transport requirements and procedures. NORM impacted materials or waste with activities greater than 70 Bq/g fall under the requirements of the packaging and transport of nuclear substances regulations (PTNSR). NORM Waste or materials with activities less than 70 Bq/g fall under provincial authority and only require a manifest. This activity of 70 Bq/g assumes a single radionuclide. NORM waste can have radionuclides from both the U238 and Th232 decay series and as such are considered a mixture of radionuclides. The PTNSR outlines the method for determining the activities of mixtures to verify if the PTNSR apply for the mixture.
Note: Prior to shipment you must determine the activity of the waste to verify appropriate regulations applicable to the shipment. Laboratory analysis can verify the activity of a NORM impacted shipment or estimates, by a qualified radiation expert, can be utilized.
Normtek has a mobile laboratory for completing sample analysis prior to transport. The CNSC requires transporters of NORM impacted materials or waste have a written Radiation Safety Program if activities fall under their regulatory control (Radiation Protection Program Design for the Transport of Nuclear Substances GD-314).