Modelling PWR contamination buildup

High radiation dose rates on the primary circuits and components caused by contamination buildup are a severe handicap in plant operation and maintenance. Therefore, several attempts have been made to predict the rate and extent of dose 

Some of the existing codes shall be shortly addressed in the following to give an impression of the nature and amount of data required to describe the process of contamination buildup as completely as possible. 

Nevertheless, it was reported that the application of the Pactole code to different PWR plants yielded results that were in reasonable agreement with the prac- 

The Cora code was developed in the US it is based on the principal aspects of corrosion product transport in a PWR plant and it permits a time-dependent calculation of the radionuclide activities and concentrations, of the corrosion product masses and the activity concentrations they contain, as well as of the radiation levels at the primary circuit surfaces. As can be seen from Fig. 4.41., where a schematic diagram of the improved code Cora-II is shown (Kang and Sejvar, 1985), this code uses 8 nodes for the activity transport and 2 additional nodes for the mass transport, taking into account the total masses inside and outside the neutron field. In each node the general mass balance is defined according to 

In the transfer of a nuclide from one node to another, a transport is assumed which is proportional to the amount of nuclide present and to the mass transfer coeffi- 

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