Primary Circuit Decontamination

Effective and comprehensive reduction of the dose rate at the NPP

The  ASDOC-procedure developed by Siempelkamp NIS, serves as an efficient decontamination of the primary system and the assistive systems in a nuclear power plant using the existing operating medium and the power plant’s operating systems:

A S D O C = Advanced System Decontamination by Oxidizing Chemistry.

During power operation of a nuclear power plant and an operating temperature of > 180°C, protective oxidic coatings are formed on the medium wetted inner surfaces of the pipelines and components. Here, radionuclides are incorporated in the oxide matrix. The aim of this chemical decontamination process is to dissolve that oxide coating and to retain it in a solution, in order to (be able to) eliminate the intetrated radionuclides. The ASDOC-procedure may be implemented until the desired decontamination result has been achieved: The radionuclide occupancy of metal surfaces is lowered to such an extent that the metallic material may be freely recycled or melted. 

The ASDOC-procedure offers the following innovative advantages:

  • Implementation of the primary circuit decontamination is done by NPP-owned staff and process control outside the containment is carried out by Siempelkamp NIS  
  • No complex assembly of equipment in the radiation field
  • Opening of the primary circuit is not necessary: cooling water is not being lead across additional external installations, which significantly reduces the risk of leakage
  • Solely formation of soluble compounds and no loss of oxide products
  • Low and well controllable use of the chemicals
  • Reduced generation of contaminated waste .

For the chemical decontamination of PWR and BWR primary systems and the assistive systems in the nuclear power plant, Siempelkamp NIS Ingenieurgesellschaft developed the ASDOC Process. This chemical decontamination process is completely operated and controlled by the nuclear site installations.

Further information:
ASDOC – Chemical Decontamination Process for Primary Systems