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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 StrSchV resp. § 31a RöV


Occupational exposed persons

Persons under 18 years

Effective Dose
20 millisievert
1 millisievert
Lense of the eye
150 millisievert
15 millisievert
Extremities
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,
  • handle sealed high-radioactive sources,
  • unsealed radioactive substances
  • or are exposed to an enhanced level of civilian (e.g. nuclear power station) or natural radiation (e.g. radon in mines, show caves, drinking water facilities or cosmic radiation during flights) at their workplaces.

Limit of the effective dose per year

The permissible occupational radiation exposure for these persons is limited and officially supervised. 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). Beside the limit for the effective dose there are additional dose limits for organs.

Special dose limits for persons under 18 years

For juveniles exist additional dose limits. 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 exists also lower organ dose limits.

Special dose limits for women

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

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

Special life time dose

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

Exceeding 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 permission.
The exceed of a dose limit is very rare in Germany: In the last years the 20-milisievert-limit was only less than ten timess exceeded. In general, the actual exposures remain almost always 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, it is additionally required to keep radiation exposures as low as reasonably achievable, taking the state of science and technology and the circumstances of the individual case into account.

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 measurably exposed workers is 0.6 millisievert,
  • a value that reached only 3% of the permitted annual limit of 20 millisievert.

Dosimetry

For the dose measurement of radiation exposure on 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), then these persons are additionally monitored by officially approved dosimetry services for incorporation. These services monitor the workers regularly or at special occasions if they have incorporated radionuclides into their body. 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 observes the dose limits. The route doses of the members of the aircraft personnel are calculated by the airlines by using certified computer programmes for dose calculation. These doses are sent via the Federal Office for Civil Aviation to the BfS.

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