Overexposure to Radiation Workers

Print View Posted on: 17 July 2012

Event Date: 08 October 2011 Event Type: Irradiation/Accelerator Facility
Event Location: United States of America, Central New Jersey INES Rating: 2 (Final)

UPDATE 26 JUNE 2012: One of the service personnel (radiation worker) received 172 mSv (17.2 rem) whole body dose and 1 Sv (101.3 rem) to the extremities. Another of the service personnel (radiation worker) received 175 mSv (17.5 rem) whole body dose and 616 mSv (61.6 rem) to the extremities. The facility radiation safety officer received 114 mSv (11.4 rem) whole body dose. The doses for the three individuals were determined by the actual reading of individual dosimeters. Four additional radiation workers received whole body doses that ranged between 15 mSv (1.5 rem) and 35 mSv (3.5 rem).

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ORIGINAL 11 OCTOBER 2011: During loading of a 44.8 TBq (1210 curie) Co-60 source into a research irradiator at the licensee’s New Jersey facility, approximately 10 cm of the 20 cm source somehow became dislodged for approximately 25 to 30 seconds, exposing two service personnel (radiation workers) and a radiation safety officer (RSO) the licensee had employed under reciprocity using a Pennsylvania license. The service personnel were working under the supervision and direction of the Pennsylvania licensee. The insertion tool prevented the workers from re-inserting the dislodged source quickly. However, the workers were able to shield the source with titanium and forced it into place by breaking off the insertion tool. The service personnel received approximately 81 and 77 mSv (8.1 and 7.7 rem) each to the whole body based on readings obtained from electronic dosimeters the workers were wearing. In addition, the two service personnel received an estimated 500 to 600 mSv (50 to 60 rem) to the extremities. The RSO received approximately 114 mSv (11.4 rem) to the whole body. This dose was based on an actual reading of the individual’s dosimetry which was sent for processing. In addition, four other workers who were in attendance during the attempted source exchange received approximately 15 mSv (1.5 rem) to 35 mSv (3.5 rem) whole body. Final dose assessments are being conducted.

INES Rating: 2 - Incident (Final) as per 26 June 2012
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

Cynthia Jones
Nuclear Regulatory Commission (NRC)

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