Overexposure to Worker

Print View Posted on: 22 September 2020

Event Date: 30 June 2020 Event Type: Radiation Source
Event Location: United States of America, Alvin, Texas / Ineos Oligomers Chocolate Bayou INES Rating: 2 (Final)

The State of Texas reported that as a result of the failure of a fixed gauge on June 30, 2020, a worker likely received a dose exceeding 250 mSv (25 rem). The rotary element and the source tube came partially out of the gauge and while employees tried to put them back in, the source and the cover plate holding it came out of the source tube. Workers thought the 3.5 GBq (95 mCi) Cs-137 source was still in the gauge housing and picked up the pieces without knowing that one of the pieces was the source. One worker put the source into his shirt pocket. The licensee is conducting a re-enactment to collect information for dose reconstruction and calculation. The Radiation Emergency Assistance Center/Training Site (REAC/TS) has been contacted for biodosimetry. The preliminary estimate of the dose received exceeds the U.S. statutory limit for total effective dose equivalent. NRC EN54706

UPDATE: A total of seven individuals were exposed to the source. Three people held the source in their hands, and one of them also placed the source into his shirt pocket. Four individuals were near the source at distances ranging from 6 inches to 6 feet. Three of the exposed individuals were radiation workers and four individuals were members of the public. Event re-enactment and dose calculations were completed. Serial blood counts were conducted under the guidance and direction of REAC/TS. Whole-body doses to members of the public were ranged from less than 0.01 mSv to 0.05 mSv (0.001 rem to 0.005 rem). Whole-body doses to radiation workers were ranged from 0.08 mSv to 410 mSv (0.008 rem to 41 rem). The individual that received the highest dose was the radiation worker who placed the source into his shirt pocket which ranged from 380 mSv to 410 mSv (38 rem – 41 rem). This individual also received the highest dose to an extremity which was 310 mSv (31 rem) to the hand. No adverse clinical and physical biological effects were observed as a result of this event. The dose received by the radiation worker that placed the source into his pocket exceeds the U.S. statutory limit for whole body dose of 0.05 Sv (5 rem).

INES Rating: 2 - Incident (Final) as per 18 September 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

Patricia Milligan
Nuclear Regulatory Commission (NRC)

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