INES-event
INES 2

Radiography overexposure

On September 16, 2010 the radiation safety officer of a licensed industrial radiography company notified the Regulatory Authority of an overexposure of a gammaradiography worker. The worker was exposed by a 0.4 TBq (11 Ci) cobalt-60 source, with the dose exceeding the annual dose limit 50 mSv for radiation workers. The incident occurred when the radiographer entered the bunker without retracting radiation source to its shielded position. The worker spent about 4 minutes in the bunker while replacing the radiography film. Inadvertent exposure came evident to the worker when he started the next exposure.

Radiographer’s personal TL dosemeter was analyzed next day by the dosimetry service and a dose of 58 mSv was reported to the licensee and Regulatory authority.

The incident was a consequence of poor safety culture and maintenance of safety equipment. The radiographer and the area supervisor both realized that the radiation dose rate meter in the radiography site was out of batteries and inoperable, and hence not working. The work was started regardless relying on the alarming personal dose rate meter carried by the radiographer. Also the personal dose rate meter was rendered inoperable by battery failure before the incident, but the radiographer had carried on with the work regardless. These lapses in safety are in direct conflict with regulatory requirements for gammaradiography in Finland.

The exposure would have been avoided had the individual been following written procedures and had properly maintained radiation dose rate meter and a personal radiation alarm.

The event was classified as level 2 on the INES scale.

Press releases in finnish and swedish http://www.stuk.fi/stuk/tiedotteet/fi_FI/news_604/

Location: Inspecta Oy/Kotka
Event date: Thu, 16-09-2010
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