Safety of sealed radioactive sources
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Safety of sealed radioactive sources in Germany

Blood Irradiator

Figure 1: Blood irradiator (Reference: Identification of Sources and Devices – Reference Manual, IAEA Nuclear Security Series, 2007)

About 100.000 sealed radioactive sources are used in Germany in industry, medicine, research and in agriculture.

Areas of use and legal basis

Most common areas of use for sealed sources in industry are calibration, material testing, product irradiation and sterilisation as well as level and density measurement. In medicine sealed sources are mostly used in radiation therapy and blood irradiation, where cobalt-60, iridium-192, caesium-137, strontium-90 and americium-241 are the dominating radionuclides. The activities used in these areas range from some Kilobecquerel for testing and calibration sources to several Terabecquerel in radioactive sources for irradiation facilities.

Gamma radiography projector

Figure 2: Gamma radiography projector (Reference:; Identification of Sources and Devices – Reference Manual, IAEA Nuclear Security Series, 2007)

Use of radioactive sources in Germany is generally subject to government supervision according to the Atomic Energy Act and requires a licence according to the Radiation Protection Ordinance. The licence is granted by the competent federal state authority in Germany after examination for compliance with legal requirements.

Handling of sealed sources without a licence is only allowed for sources containing activities below the so-called exemption level or sources fixed within equipment built to a type approved design. Exemption levels have been specified by the Radiation Protection Ordinance in accordance with international (IAEA) and European limit values (EU Guideline 96/29/EURATOM). The term “exemption level” refers to an activity level associated with negligible radiological hazard assuming proper use of the radioactive source.

Duties of source owners regulatory control

The receipt and transfer of sources are subject to mandatory reporting. The application of radioactive sources is monitored for proper handling by officially appointed radiation protection officers. In addition, the regulatory authority may carry out a review of the licensee at any time. Safety-related incidents during the use of sealed sources, such as technical malfunctions of the device, operating error or theft, must be reported immediately to the responsible authority. Before transferring a source, it must be guaranteed that the recipient has a valid handling licence referring to that source. The recipient must receive a certificate, stating that the source is leak-tight and free from contamination.

Transport of radioactive sources is subject to the Transport of Hazardous Goods Ordinance and also requires authorisation. Carriage without governmental monitoring is permitted only for sources with levels of activity below the exemption level (see above) and for the so-called exempted packages. The transport packaging of radioactive sources must comply with the provisions of the European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR).

The working life of sources in use varies with the strongly varying half-lives of the used radionuclides. If the sources are not disposed of directly by the licensee upon expiry of their operating life, the equipment together with the source remaining in the device must be returned to the equipment manufacturer. The manufacturer checks whether the radioactive source is reusable or returns it to the source manufacturer. Disused sources or devices are delivered to Federal state collecting facilities.

As until today no endangerment through sources illegally disposed of or lost in Germany

Radioactive source from a teletherapy unit

Figure 3: Radioactive source from a teletherapy unit, found at the accident in Thailand (Reference: The Radiological Accident in Samut Prakarn, IAEA, 2002)

Although handling of radioactive sources is subject to governmental controls, it cannot be completely excluded that a sealed source gets lost or that an orphaned source will be found. Such incidents must be reported immediately to the regulatory authority. All incidents will be recorded and analysed on a national level. A brief summary of annual incidents in Germany is published in the annual report of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (Title: “Umweltradioaktivität und Strahlenbelastung”).

Nearly 500 reported incidents associated with loss or discovery of radioactive sources were recorded between 1991 and 2008 throughout Germany. These sources, mostly disposed of ignorantly, were often discovered in junk or waste containers, because most of the scrap metal or waste companies employ appropriate radiation measurement devices. Since the levels of radioactivity of these lost or found sources are low in most cases (e.g. accidentally discarded ionising smoke detectors), potential misuse is not expected to pose a high hazard.  

Central German register permits complete backtracking of high-activity sealed sources

However, eleven findings of sealed sources involving high levels of activity were reported between 1991 and 2008 in Germany, but did not end up in accidents. The extent of dangers associated with sources of this kind was seen in an incident in Thailand in 2000, when a cobalt-60 source from a teletherapy device was accidentally taken to a junk yard and unknowingly opened. As a result significant radiation exposures occurred and several people suffered from radiation sickness or died. This example emphasises the danger posed by radioactive sources when orphaned as a result of lacking monitoring. So far, accidents of this kind have not occurred in Germany.

Against the background of possible accidents, measures to increase safety when handling radioactive sources have been discussed on an international level at the International Atomic Energy Agency (IAEA) since the 1990s. Especially in view of the altered level of safety after the attack on September 11, 2001, international regulations have tightened significantly.

In Germany, legal regulations were enacted concerning control of so-called high-activity sealed radioactive sources (HASS) in 2005. Those are sealed sources which have such high levels of activity, that improper handling may be associated with a high radiological hazard. In addition to previous regulations, the delivery and acquisition of a HASS have to be recorded in a central register (HRQ-register) at the Federal Office for Radiation Protection (BfS) since 2005. The HRQ-register allows traceability of all high-activity sealed radioactive sources in Germany. The new regulations integrated the obligation to take back a HASS by the manufacturer of the source into law, too.

International information system for lost radioactive sources

Because the transport of radioactive material through global scrap trade is a trans-national problem, the IAEA has been operating an information system to transmit data on lost radioactive sources on a global scale for several years. Due to this information system for example one case was solved in 2003 involving two sealed sources found in scrap metal in Germany, that had been stolen in Nigeria. In order to avoid such incidents or minimise their consequences, further improvements of existing security measures are planned for the future.


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