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Ionising radiation

Environmental Radioactivity - Medicine - Occupational Radiation Protection - Nuclear Hazards Defence

Ionisierende Strahlung

Procedure of Incorporation Monitoring

For the handling of sources of ionising radiation, dose limits for the workers have been laid down in the German Radiation Protection Ordinance (Strahlenschutzverordnung - StrlSchV). For the effective dose this value is 20 mSv per year. When handling open radioactive substances, the body dose can be composed of external and/or internal radiation exposure, depending on working conditions, the chemical form of the used substances and the type of radionuclides.

Internal exposure always occurs when radionuclides have entered the body, this is referred to as incorporation. The activity taken up by inhalation or ingestion must not result in exceeding the dose limits (effective dose or organ dose, respectively) of the StrlSchV. Neither must these dose limits be exceeded by the sum of the contributions of internal and external radiation exposure.

Methods and responsibilities

The monitoring of incorporation is regulated in the German Guideline of Physical Radiation Protection Control. The following monitoring methods for the determination of the incorporated activity are commonly used:

The first two methods are carried out by approved laboratories responsible for incorpration monitoring (ALIM). These laboratories are accredited by the respective competent German Federal States authorities. The third method is used when the first two methods are not suitable. This is the case if for example the radionuclides to be monitored are too short-lived or the methods are not sensitive enough. In this case the responsible radiation protection supervisor and/or the radiation protection officer at the site allows to take appropiate actions.

Retrospective dose assessment

It is the task of incorporation monitoring to assess retrospectively if occupationally exposed workers incorporated radioactive substances. The activity possibly incorporated is determined and the body dose resulting from this uptake is assessed using the monitoring data. This means that incorporation monitoring on the basis of measurements serves to determine retrospectively a radiation exposure. It is not intended to achieve precautionary radiation protection tasks as, e.g., optimization of radiation protection measures.

Since 1996, the responsibility for "incorporation monitoring" is carried by the Coordinating Office on Incorporation Monitoring at the Federal Office for Radiation Protection (BfS). The Coordinating Office is responsible for all matters of principal and special questions concerning incorporation monitoring already not covered by the German Federal States. The spectrum of information and consultancy comprises both the activity determination in the respective medium (body, urine, faeces and so on) and the dose assessment.

State of 2016.11.10

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