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Preventing loss of sourcesWhile proper training and experience will reduce the risk of radiation exposure when sealed radioactive sources are used, the vast majority of serious accidents in industrial use are due to a source that has been lost or stolen. Industrial gamma radiography sources are at risk of loss because they are mobile and used in less controlled settings. Proper maintenance of equipment and good operational practices and procedures can reduce the risk of a source being lost in the first place. A source should be transferred to the waste operator or returned to the manufacturer as soon as it becomes disused.
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| Maintain equipment properly as recommended by the manufacturer, particularly the mechanical moving parts, to reduce the likelihood of a source failing to retract into the shielded position. |
| Check routinely for crank problems, for signs that the cable is kinked, or for problems with pigtail coupling. |
| Always have a survey meter present when working with the source. Test the survey meter prior to each use to make sure it is working properly and regularly service it. |
| Store sources in a secure storage facility when not in use. Store keys separately from the source device. |
| Check the source device before leaving for the work site to make sure the container is locked. Monitor with a survey meter to confirm the source is in the shielded position. |
| Never transport a source container with the key in the lock. |
| Use radioactive sources only in a controlled area with barriers, warning signs, and shielding in place. Use a survey meter to monitor the area during exposure. |
Use sources when few or no other workers will be in the area (lunch breaks, after hours, etc). Advise managers and workers when a radiation exposure is to be done. |
| Sources that are no longer in use should be returned to the supplier if possible or to the national waste operator in the country. |
Industrial radiography accidents occur usually because the radiographer
(or other qualified operator) does not make a proper radiation survey.
Only through the proper use of a survey meter can the radiographer know
the actual location of the source and prevent accidents.
Using a survey meter, a radiographer can make an initial survey of the device when removed from storage to confirm that the source is not exposed. This also provides a baseline for comparison with later surveys. Any unusual readings should be investigated.
The radiographer should observe the survey meter while exposing the source during operation. A drastic increase in radiation intensity should be seen as the source emerges from the shielded container. As the source moves through the guide tube, the radiation intensity should steadily decrease.
| Store sources securely when not in use. |
| Maintain good records of sources in storage. |
| Conduct a regular physical inventory of all sources. |
| Maintain and service all radioactive sources according to manufacturer’s instructions. In particular, owing to the harsh conditions of use, the equipment should be regularly inspected to make sure that the labelling of the source is still visible. |
| Conduct a proper survey before and after use of the source, including around the storage site, in the transport vehicle, and at the site where the source is used. |
| Make a proper survey with a survey meter to locate a lost source. |
| In well logging, the greatest potential for an accident is loss of the radioactive source down the well. In the event that a source is lost, reasonable attempts should be made to remotely retrieve the source from the well, and the responsible regulatory authority should be notified to make a safety assessment. Care should be taken not to damage the source during recovery. The site should be monitored for contamination after retrieval. Damaged sources should be transferred to the waste operator for long term management. |
| Take measures to minimize the risk of sources being stolen during storage and transportation. |
All users of sealed radioactive sources should have a contingency plan in place for emergencies, such as a damaged, lost, or stolen source. The plan should detail who is responsible, who must be contacted, and how to get outside assistance to deal with the emergency if necessary.
