On Tuesday (25 July) NTP Radioisotopes (Europe) S.A received a package with a used radioactive source. The package was flown from Egypt and arrived at Brussels Airport via Zurich Airport, where it remained temporarily stored since 13 July. NTP Radioisotopes (Europe) S.A is a Belgian company in Fleurus, specialized in the production of radioactive industrial sources that can be used for industrial gammagraphy.
During inspection of the package the dosimeter of one of the NTP employees detected an abnormally high radiation level in the vicinity of the package, exceeding the limits stipulated in the regulations for the transport of radioactive material. The company shielded the package, brought it to a safe place and informed the Federal Agency for Nuclear Control (FANC).
In consultation with the FANC and under the supervision of NTP, the package was safely opened in a shielded cell where they discovered that the radioactive source was not in the primary container intended to shield the radioactive source and to limit the radiation outside the package.
Inspectors of FANC measured the radiation level around the package, the radiation level in the vicinity of the package was above the limit of 2 millisievert (mSv) per hour. The sender did not correctly label and mark the package and it was not sealed. Furthermore, the sender prepared the package for transport and sent it without measuring the radiation level.
The FANC undertook analysis in order to define the localisation of the package and of the people during the transport, as well as the dose rates they could have been exposed to. Because one cannot conclusively say where exactly the package was stored in the airplane’s cargo space, the FANC based its analysis on the most conservative calculations, taking into account all possible storage positions.
The results showed that the maximum dose a passenger sitting ‘right on top’ of the package could have been exposed to, is 6.6 mSv for the Cairo-Zurich flight, and 3.1 mSv for the flight between Zurich and Brussels. The dose limit for public exposure is 1 mSv per year in the knowledge that one person living in Belgium is exposed, on average, to about 2.8 mSv per year due to natural radiation. For your reference, the average dose of a CT scan of the abdomen is 8 mSv. A single exposure such as the one faced during this incident does not represent a significant increase of the health risk for the people exposed. There is however no risk of radioactive contamination for these people, and they are not radioactive themselves.
The FANC informed the shipment expeditor and the various involved nuclear authorities of the incident and the non-compliance with the nuclear materials transportation regulations. These authorities will now jointly monitor the incident and take the necessary measures in order to prevent this type of incident from reoccurring.
After analysis, the incident was provisionally classified at level 2 of the INES scale. INES (International Nuclear Event Scale) is a tool for promptly and consistently communicating to the public the safety significance of events associated with sources of ionizing radiation. This scale counts seven levels, ranging from 1 (anomaly) to 7 (severe accident).