Overexposure of two workers during radiography

Print View Posted on: 22 February 2020

Event Date: 29 November 2019 Event Type: Radiation Source
Event Location: Germany, Company for non-destructive testing INES Rating: 2 (Final)

Overexposure of two workers during radiography

Two employees of a company for non-destructive material testing were exposed to 30 and 100 mSv respectively.
On 29th November 2019, the employees tested materials with a Ir-192 source in the bunker of the company.
The employees have to wear dosimeters equipped with acoustic alarms. The radiation officer has to check in-situ with a portable radiation measuring device that the source is placed in its shielded position.
On November 29, 2019, an employee forgot to retract the source into the shielding between two tests. Nevertheless, he entered the bunker to change the material. This employee received a dose of 100 mSv according to the analysis of the official dosimeter. The other employee supported him only with carrying the materials and received a dose of 30 mSv. The electronic dosimeters had been carried by both employees but were switched off. The radiation officer did not perform the prescribed radiation measurement.
The employee did not talk about his mistake with the management and his colleagues, though he noticed before the next test that the source has not been in the shielded position.
The competent authority received the analysis of the official dosimetry in December 2019 and ordered an employment ban for the two employees from all radiation works until the cause analysis has been finished. Medical tests of the two employees confirmed the overexposure and on February 13, 2020 the employee admitted his mistake. The competent authority was in close contact with the company and was on-site on February 14, 2020.
In the course of the investigation by the authority the event analysis could be completed, and important lessons learned.

INES Rating: 2 - Incident (Final) as per 22 February 2020
Release beyond authorized limits? No
Overexposure of a member of the public? No
Overexposure of a worker? Yes

Contamination spread within the facility? No
Damage to radiological barriers (incl. fuel damage) within the facility? No

Degradation of Defence In-Depth No

Person injured physically or casualty? No
Is there a continuing problem? No

Michael Maqua
Gesellschaft für Anlagen und Reaktorsicherheit

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