Am-241 source melting

Print View Posted on: 16 October 2018

Event Date: 26 July 2018 Event Type: Radiation Source
Event Location: Finland, Finnish steel factory INES Rating: 1 (Final)

An orphan Am-241 source, which was inadvertently included in scrap metal, was melted on July 26th, 2018 in a Finnish steel factory. The melting of the source was detected by the radiation pulse rate monitoring within the steelworks smelting process.

The activity of the melted source can not be determined exactly. In the first measurement the activity concentration was 60 Bq/g. It is estimated that the activity of the melted source is 1110 MBq. The source is traced by the operator to stainless steel scrap delivered from Central Europe. Origin of the scrap metal is unknown.

Am-241 is captured in the dust suppression and filtration with other particulates in the dust phase and thus there were no environmental releases. In an Am-241 melt the steel remains uncontaminated. Nobody was exposed.

The factory has screening detectors of incoming scrap. Despite of the modern screening technology used, the source could pass through because of americium’s low gamma energy, which is easily attenuated by other scrap.

INES Rating: 1 - Anomaly (Final) as per 16 October 2018
Release beyond authorized limits? No
Overexposure of a member of the public? No
Overexposure of a worker? No

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

Degradation of Defence In-Depth Yes

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

Heli Hoilijoki
Radiation and Nuclear Safety Authority (STUK)
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