Presence of Am-241 (americium-241) in row material for production of Copper

Site with SIR or place of the event: Border checkpoint - Kulata

Event description:

On 23^rd May 2008 NRA received notification (official letter) from “Dial” Ltd. for presence of Am-241 in row material (fine slag, containing around 30% copper), exported to Greece by “Sofia med” S.A. (successor of the former Non-ferrous processing works, at present branch of the Greece company “Halkor” S.A.). A protocol for performed by “Dial” Ltd. radiometric measurements of samples of exported to Greece raw material for copper production was submitted to NRA. A presence of Am-241 was around 2 times above the norm of 100 Bq/kg in compliance with the Regulation № 25 of Ministry of Health (Official gazette, № 64/05 August 2005). NRA has notified for the case the Greek Atomic Energy Commission.

According to the Regulation for Radiation Protection During Activities with Sources of Ionising Radiation (Official gazette, № 74/24 August 2004), the reprocessing of metals is permitted if the content of Am-241 is up to 1000 Bq/kg. The same boundary level in terms of specific activity for Am-241 content (1000 Bq/kg) is accepted also in EU for the reprocessing of metals (scrap metal processing).

On 26^th May 2008 the NRA and the National Centre for Radiobiology and Radiation Protection (NCRRP) made an inspection in “Sofia med” S.A. in connection with the case. Elevated radioactivity was detected in one of the containers with slag, generated from the furnaces for melting of row material and producing copper during the inspection. The container was separated for surveillance of the type and the amount of incorporated radioactive substance. The specialised laboratory of the NCRRP performed the analysis of the samples taken from the respective container.

During the inspection the inspectors have not registered any rise of the gamma background on the territory of the “Sofia med” S.A. The measured values were not very different from the typical for the area natural radiation background and vary between 0,12 µSv/h and 0,16 µSv/h.

The most probable reason for the presence of the Am-241 into the row material, exported to Greece during the period of March-April 2008, is melting of a radioactive source, containing Am-241, which has gotten accidentally into the scrap metal, processed in “Sofia med” Ltd. Automated devices (portal monitors) are mounted on site for radiation check of all materials and row materials passing through the entrance/exit of “Sofia med” Ltd. Nevertheless it is possible with the scrap metal radioactive sources with very low activity, which cannot be registered, to be melted. “Sofia med” Ltd. imports scrap metal from over 20 countries that is why it is not possible to determine the origin of Am-241 in the furnace slag.
NRA and NCRRP continue the work oh this case.