Calculation of radiation exposure to the public

The radiation exposure in the vicinity of each nuclear installation is calculated for a (hypothetical) representative person.

By means of the assessed discharges provided by the operator the radiation exposure in the vicinity of each nuclear installation is calculated for a representative person.

This representative person is a hypothetical individual, whose behaviour in regard to location and consumption habits results in higher exposure to radiation (conservative assumptions).

Until 2020, the radiation exposure for the public was calculated for a reference person instead of a representative person. The reference person is also a hypothetical individual whose behaviour in regard to location and consumption habits results in an exceptionally high radiation exposure (conservative assumptions). Extreme lifestyle situations are not excluded.

In general, the calculated radiation exposure for the reference person is higher than the one for the representative person.

Calculating radiation exposure using computer simulation

Computer-based dispersion models are applied to model the transport processes of radionuclides from a nuclear installation into the various areas of the environment (see figure "Modelling of the transfer of radionuclides").

Modelling of the transfer of radionuclides starting from the discharge of radioactive substances from the exhaust air stack through the biosphere to humans.

The radiation exposure of a representative person is determined conservatively, i.e. tendentially too high, from the calculated concentrations of radioactive substances in the various environmental media (e.g. by means of the dose model DARTM).

In accordance with the Radiation Protection Ordinance, the exposure must not exceed 300 microsievert for the effective dose in one calendar year.

The greatest proportion of radiation exposure during normal operation is due to the radionuclide carbon-14 (see figure):

Dose fractions of the radioactive substances discharged in exhaust air during the operation of nuclear power plants

In this context, especially the intake of carbon-14 in the form of carbon dioxide through food (ingestion) is relevant to the dose.

Activity discharges in exhaust air

The radioactivity discharges in exhaust air add up to a radiation exposure of

• less than 1 microsievert in one calendar year for toddlers
• less than 1 microsievert in one calendar year for adults.

In the period under review from 1990 to 2023, these values are significantly less than one per cent of the natural radiation exposure of the public (see figure):

Calculated effective dose of the representative person “adult” and "child 1-2 years" due to discharges in exhaust air in year 2023.

Activity discharges in waste water

About 100 terabecquerel tritium, 1 gigabecquerel of other activation and fission products are annually discharged with waste water from nuclear facilities.

The discharged amount of activity of alpha emitters is about 1 megabecquerel. (tera=10¹², giga=10⁹, mega=10⁶).

Activity discharges with the waste water from NPPs in 2023

The conservatively calculated radiation exposure due to waste water is

• less than 6 microsievert in one calendar year for toddlers
• less than 2.3 microsievert in one calendar year for adults

and is thus below 1 percent of the legal limit.

Radiation exposure in the ambience of NPPs by discharge of radioactive material in aquatic systems 2023

Reporting is a statutory mandate

The radiation exposure of the public determined from the activity discharges in exhaust air and waste water is documented in the parliamentary report and in the annual report "Environmental Radioactivity and Radiation Exposure" of the Federal Environment Ministry.