Alarming of the portal radiation monitoring system

Site with SIR or place of the event: “Kremikovtsi” S.A. – Sofia

Event description:

The Emergency centre of the NRA was notified that on 19^th September 2009 the portal radiation monitoring system of the “Stomana Industry” S.A. – Pernik detected elevated radiation level in a truck, carrying scrap loaded container, owned by “Realmet” Ltd. The detailed measurements have shown slightly elevated radiation levels, up to 0,51 µSv/h, on the surface of a small area close to the corner of the container. The container has been separated and secured.

On 23^rd September 2009 experts of the NRA, GD ”NSCP” and NCRRP-MH arrived at the place. The container was unloaded thoroughly. It was determined that the elevated radiation levels originate from the contaminated inside by yellow-brown settlings tubes (Ø30cm) as well as from the deposited on the container bottom brown slag. Following a field spectrometric analysis, the presence of the radioactive isotope Ra-226 (radium-226) was identified and the measured values of the gamma dose rate in contact were up to 1,18 µSv/h.

The settlings of the contaminated tubes as well as the slug were separated from the remaining scrap metal. A sampling and the following measurement in the NCRRP showed a low level of radioactive contamination – under 1000 Bq/kg. It is forthcoming the corresponding procedure for treatment of slightly naturally contaminated radioactive materials, under the management of the NCRRP-MH, to be applied for the separated radioactive material.