Discovered radioactive sources in railway wagons, loaded with scrap metal

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

Event description:

In June and early July 5 radiation incidents, connected with railway wagons loaded with scrap, have arrised on the territory of “Stomana Industry” S.A.– Pernik. The Emergency centre of the NRA was being notified immediately about these situations. The latter arose after signals of the portal radiation monitoring system of the “Stomana Industry” S.A.

The first signal was on 15^th June 2008. The detailed measurements have shown slightly elevated radiation levels, up to 0,13 µSv/h, on the surface of a small area on the side of the wagon. As a reference, the values of the natural gamma background in the area of the Pernik town are between 0,07 and 0,11 µSv/h and in the rest parts of the wagon – not over 0,05 µSv/h (they are under the natural background, due to the shielding effect from the loaded wagon). Following a field spectrometric analysis, the radioactive isotope Ra-226 (radium-226) has been identified.

On 22^nd June 2008 the portal radiation monitoring system signals again for the presence of radioactivity. The measurements have shown elevated gamma dose rate – up to 0,95 µSv/h. Following a field spectrometric analysis, the radioactive isotope Ra-226 (radium-226) has been identified.

In both cases the origin of the radiation was from control military vehicle gauges. The luminous dials paint contains Ra-226.

The discovered on 24^th June 2008 source of ionising radiation source was Th-232 (thorium-232), as shown by the spectrometric analysis. The measured values of the gamma dose rate have been up to 0,65 µSv/h.

Again this time the details, causing the radiation, have been contained in a metal box from a military vehicle. The measurements have shown gamma dose rate up to 15 µSv/h at 10 cm and up to 180 µSv/h on the surface of the details.

Paint on the vehicle control gauge has activated the portal radiation monitoring system of “Stomana Industry” S.A. on 29^th June 2008. The measured values of the gamma dose rate have been up to 0,35 µSv/h. Following a field spectrometric analysis, again the radioactive isotope Ra-226 (radium-226) has been identified. The measured values of the gamma dose rate at 10 cm from the detail have been up to 3,1 µSv/h.

The next signal for elevated radiation levels in a railway wagon loaded with scrap was on 7^th July 2008. The detailed measurements have shown elevated radiation levels, up to 2 µSv/h, on the surface of a small area on the side of the wagon. Following a field spectrometric analysis, the radioactive isotope Cs-137 (cesium-137) has been identified.

All the discovered sources have been put in a safe place for temporary safe storage, and latter will be disposed as radioactive waste by the State Enterprise “Radioactive Waste”.

Complementary information (16^th July 2008)

In respect to discovered source of ionising radiation Cs-137 in scrap metal on the territory of “Stomana Industry” S.A.– Pernik town, NRA made additional checks and analysis of the situation and the following was cleared:

1. The most probable origin of the source inside the scrap, delivered by the “Kemsteel” Ltd. to “Stomana Industry” S.A. is from “Petar Karamintchev” plant – Ruse. At present the latter is under liquidation procedure.
2. During the performed on 15^th July 2008 after NRA request additional radiation measurements on the territory of the “Petar Karamintchev” plant – Ruse, Regional Inspectorate for Protection and Control the Public Health – Ministry of health and “Control Dangerous Substances Service – Ministry of Internal Affairs have discovered another one source, mounted inside a cistern. The measured gamma dose rate has been up to about 30 µSv/h, which exceeds many times the natural radiation gamma background on site (about 0,10 µSv/h).

NRA arranged the discovered in the plant radioactive sources to be urgently transported and disposed as radioactive waste by State Enterprise “Radioactive Waste”. The deconstruction activities on the territory of the plant were temporary stopped before the transportation. Other radioactive sources have not been discovered on the territory of the plant.