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Ionising Radiation > Occupational Radiation Protection > Dose Limits

Dose limits in occupational radiation protection

Dose limit per calender year according to § 55 Radiation Protection Ordinance resp. § 31a X-ray Ordinance


Occupational exposed persons

Persons under 18 years

Effective Dose
20 millisievert
1 millisievert

Organ dose: eye lens

150 millisievert
15 millisievert
Organ dose: Skin, hands, forearms, feet, ankles
500 millisievert
50 millisievert
In Germany, about 400,000 persons are dose monitored for reasons of occupational radiation protection. These people work e.g. with
  • X-ray units,
  • sealed high-radioactive sources,
  • unsealed radioactive substances.
Occupationally exposed persons can as well be exposed to
  • an enhanced level of civilian radiation (e.g. at nuclear power stations) or
  • an enhanced level of natural radiation (e.g. radon in mines, show caves or drinking water facilities or
  • to cosmic radiation during flights
at their workplaces.The permissible occupational radiation exposure for these persons is limited and officially supervised.

Limit of the effective dose per year

The dose limit of the permissible effective dose from occupational radiation exposure is 20 millisievert per calendar year in all European countries (in the USA 50 millisievert per year). In addition to the limit for the effective dose different annual limits for organ doses are defined.

Dose limits for persons under 18 years

Aadditional dose limits exist for juveniles. The permitted effective dose from occupational exposure for persons under 18 years shall not exceed 1 millisievert per calendar year. The responsible authority can specify a dose limit of 6 millisievert for juveniles aged between 16 and 18, if this is necessary for training purposes. For these groups lower organ dose limits exist as well. For juveniles at workplaces with natural radioactive substances alternative dose limits are specified.

Dose limits for women and unborn children

For occupationally exposed women the same dose limits apply as for men, provided that they are not pregnant. However, for women within childbearing years the organ dose of the uterus shall not exceed 2 millisievert per month.

With notification of an existing pregnancy the unborn child shall not receive a higher dose than 1 millisievert during the remaining period of the pregnancy.

Limit of occupational life time dose

Additionally to the dose limits specified in the Euratom Basic Safety Standards an occupational life time dose limit for workers exists in Germany: the sum of all effective doses received during the whole occupational career of a worker shall no exceed 400 millisievert.

Exceeding of dose limits

If a dose limit is exceeded, the responsible regulatory body examines the cause. Dependent on the cause it can
  • set the effective dose limit to be 50 millisievert in one year and 100 millisievert in five consecutive years,
  • impose additional requirements,
  • forbid activities,
  • set penalties and
  • withdraw licences.
The exceeding of a dose limit is very rare in Germany: During the last years the dose limit was only breached less than ten times per year. In general, the actual exposures always remain far below the dose limits. The cause is the legal requirement for optimization. In Europe, it is not only necessary to keep exposure below the dose limit, but it is additionally required to keep radiation exposures as low as reasonably achievable, taking into account the state of science and technology and the circumstances of the individual case .

The effectiveness of this so called “ALARA-principle” is evident:
  • 99% of the supervised workers have an annual dose below 3 millisievert;
  • the average effective dose of all exposed workers is 0.6 millisievert,
  • therefore the permitted annual limit of 20 millisievert was only utilized to 3%.

Dosimetry

For the dose measurement of radiation exposure at workplaces officially approved dosimeters are used, in most cases film badges. The dosimeters are distributed to the worker’s companies by officially approved dosimetry services and usually evaluated in a monthly period. The dose fracture which results from natural ambient radiation is subtracted from the measured value.

If workers handle open radioactive substances and the possibility of an up-take of radionuclides into their body cannot be excluded, (e.g. through mouth, nose or skin), these persons are additionally monitored by officially approved services for incorporation. These services monitor the workers regularly or at special occasions. All dosimetric results from both external and incorporation monitoring are regularly sent to the Radiation Protection Register of the BfS, which, amongst other things, supervises the keeping of dose limits.

The Federal Office for Civil Aviation (Luftfahrt-Bundesamt – LBA) is responsible for the supervision of air crews and controls compliance with dose limits. The route doses of the members of the aircraft personnel are calculated by the airlines using certified computer programmes for dose calculation. These doses are sent to the radiation protection register of BfS via the Federal Office for Civil Aviation.

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