Discovered radioactive source in a truck, loaded with scrap metal, in Stomana Industry” S.A.

Site with SIR or place of the event: “Stomana Industry” S.A, Pernik

Event description:

During the entrance check of a scrap-loaded truck in “Stomana Industry” S.A. (town of Pernik) some welding electrodes, containing Th-232, have been discovered.

The NRA emergency centre was notified that on 7^th July 2010 the portal radiation monitoring system of the “Stomana Industry” S.A. – town of Pernik detected elevated radiation level in a scrap-loaded truck. The truck has been stationed on a special platform on site and has been put under surveillance.

The detailed measurements have shown slightly elevated radiation levels, up to 0.45 µSv/h, on the surface of a small area on the side of the truck. As a reference, the values of the natural gamma background in the area of Pernik are between 0.07 and 0.11 µSv/h. Following a field spectrometric analysis, the presence of the radioactive isotope Th-232 (thorium-232) has been identified.

The truck has been partly unloaded. The details, causing the elevated radiation levels, has been discovered and removed from the scrap. The later represented some whole and broken welding electrodes (about 10 pcs) with Φ 10 cm and length about 35 cm. The measured values of the gamma dose rate at 1 m have been about 0.2 µSv/h and in contact – up to 5.2 µSv/h. The isotope Th-232 has been included as an ingredient of the electrodes and is causing the radiation.

The source has been packed and put in a safe place for temporary safe storage. After additional measurements the truck has been released for unloading.