Basic principles of radiation protection

The aim of Loviisa power plant's radiation protection is to take care that all official requirements are met and no limit exceeded. In addition the radiation exposure to the employees or environment has to be kept as low as practically possible.

Loviisa power plant takes all practically and reasonably possible measures in order to avoid radiation exposure to any employees or the environment. Our three basic principles of radiation protection are based on the recommendations of the International Commission on Radiological Protection (ICRP). The ICRP recommendations have also been taken into account in the Radiation Act of Finland.

Three basic principles of radiation protection

  • Principle of justifications
    The benefits of using radiation must outweigh the drawbacks.
  • Principle of optimization (ALARA principle, As Low As Reasonably Achievable)
    Radiation exposure caused by the use of radiation must be kept as low as reasonably achievable.
  • Principle of limitation
    Exposure of  radiation workers and individuals of public must not exceed dose limits.

Loviisa power plant has set a dose constraint of 15 mSv, 5 mSv below the annual five year average of 20 mSv stipulated by legislation. By setting lower dose constraints it is ensured that dose limits are not exceeded unintentionally. 

Loviisa power plant is rigorously working towards lowering the radiation dose of its personnel. Annual power plant targets in radiation control are based on the principle of continuous improvement. All unnecessary radiation exposure is  avoided. This goal requires continuous improvement in all steps of the process.  

Loviisa power plant has an action plan, so called ALARA Action Plan, that sets good practices and detailed points on what has to be taken into account in minimizing the overall radiation dose. Right measures require good knowledge of the work methods, technical development, working environment and the effects of other work conducted at the same time, co-operation and the right combination of available options in planning, timing and performing the actual work. 

For example, all mechanical seals of the reactor coolant pumps will be new antimony-free seals after the annual outage 2014. Antimony has been a binder of the graphit material in the old type seals. During operation small amounts of antimony is released to the coolant, where it activates in the reactor and attaches to large material surfaces. Antimony causes approximately half of the radiation dose of the workers at the power plant. The first antimony-free seals were introduced at the power plant in 2012 after some years of large investigation and testing. As a result of the seal replacement it is expected that the amount of radioactive antimony in the primary circuit is reduced significantly during the following years leading to lower radiation levels and thus reducing the exposure level of radiation workers.