Failed Leak Test on an Ir-192 Source

The source is not fit for use. A wipe result of 420 Bq exceeds the 185 Bq action level and indicates removable contamination, so the sealed source must be treated as leaking until proven otherwise. The fact that the exposure device is shielded does not cure a leaking capsule: contamination can spread to the guide tube, drive cable, collimator, storage bunker and personnel. The source must be removed from service immediately and quarantined in the bunker or another controlled location. The RSO should survey the device exterior, guide tube, collimator, storage area, transport route and the radiographer’s hands and clothing. Personnel should be checked for contamination and dosimetry reviewed. The overdue leak test is a separate non-compliance: the previous 6-month test was missed by a month, so the RSO must determine whether the source was used during that period and whether earlier wipes were reviewed. The damaged guide tube and collimator lock are additional reasons not to use the equipment. The refinery job should be cancelled or covered by another source and camera, not by this source.

The source cannot be used again until it is decontaminated, repaired or replaced and passes a leak test. Because the capsule may be leaking, it should not be treated as a normal special-form source for transport without assessment. The RSO should consult the manufacturer and regulator on the approved package and inner containment. The source should be placed in a leaktight inner container inside a package approved for the activity and dose rate, with the package surfaces surveyed and wipe-tested. The transport index, surface dose rate, labels and shipping documents must be completed by a trained person. The regulator should be notified of the failed leak test, the overdue test and the intended movement. The client should be told that the job is cancelled and why, without disclosing unnecessary details. If the source can be returned to the manufacturer, the RSO should arrange a certified carrier and verify driver certification. The damaged guide tube and collimator should be tagged out and replaced or repaired before any other source is used with that equipment.

Records should include the wipe test count, the survey results, photographs or descriptions of the damaged guide tube and collimator, the quarantine location, the regulator notification, the manufacturer’s advice and the transport documents. The RSO should assess whether any person received a dose from handling the guide tube or collimator; this may require reviewing TLD results, interview information and contamination surveys. If contamination was found on skin or clothing, decontamination records and dose estimates should be filed. A root-cause review should determine why the leak test was late, why the guide tube was scratched, and whether the collimator lock failed before or during use. Corrective actions should include a leak-test calendar with a 30-day advance trigger, pre-job equipment checks, replacement of damaged parts, and retraining on the significance of the 185 Bq action level. The source should not be released from quarantine until a repeat leak test is below the action level and the manufacturer or regulator confirms its status. Follow-up should also confirm that the refinery job was covered safely and that the client file is complete.