Some differences may exist between french and english regulations. Lessons learned are only a translation of those of french incident and are not adapt to english regulation.
Description of the incident
A cleaner in a laboratory was required to move a (non-compliant) 50 litre drum filled with aqueous effluents containing carbon-14 (unknown activity). During this operation, the two handles of the drum broke off suddenly and it fell to the ground. With the impact, the drum broke and a significant amount of liquid (estimated at 25 litres) spread over the ground and splashed onto the cleaner.
The cleaner immediately notified the head of the laboratory. The director of the laboratory took the cleaner to hospital where she was reassured and showered.
The qualified person in charge of radiation protection, after discussion with the regulatory authorities, proceeded with the removal of the liquid by means of a ground siphon (provided for this purpose) connected to a storage tank. The laboratory was sealed off during this procedure, which was performed by the laboratory’s volunteer staff with the assistance of a team of firefighters, specialized in the detection of radioactivity.
The floor surface still had residual contamination, which was subsequently removed by a specialized company.
The cleaner underwent urine sampling whose results were negative.
The contamination of the area was significant. The liquid had infiltrated into the many cracks in the floor of the laboratory, which made decontamination more difficult. Two maps of the contaminated premises, before the first decontamination and after the second decontamination were produced. Even after the second decontamination procedure, there remained a surface activity varying between 2 and 200 Bq/cm 2 (the highest levels being located at the position of the workbench feet and at the joints between the floor and the walls).
Lessons to be learned from the incident
This incident raised issues regarding the storage of the long half-life radioisotopes used in research. Specific lessons include:
- The drum containing the solution of carbon-14 should have been clearly labelled, so as to be easily identifiable by all staff.
- Radioactive liquids should not be stored in the general laboratory, and should be handled by a limited number of people, trained to appreciate the potential risks and follow local rules and contingency plans.
- This incident highlights the need to ensure that work surfaces (including the floor) are smooth and in good condition, in laboratories handling unsealed radioisotopes. In this incident, the poor surfaces did not allow for effective decontamination of the joints between the ground and the walls. Rounded and “ungrooved” baseboards would have facilitated decontamination.
- Any facility using unsealed radioisotopes should have suitable decontamination facilities (sinks and eye-wash facilities, plus a shower where larger volumes of radioactive liquids are handled) to deal with any staff contamination in the shortest possible time.
- Suitable personal protective protection (glasses, laboratory coat, gloves) should be worn by any individual working in a laboratory - including ancillary staff.