Analytical methods applied in contamination buildup studies

2 Analytical methods applied in contamination buildup studies 

Analytical determination of the chemical as well as the radiochentical composition of the different substances that play a role in the production as well as in the transport and deposition of the radionuclides of interest, is a very important tool for the elucidation of the mechanisms leading to contamination buildup. For this reason, a short survey will be given in the following of the available anal dical methods with particular emphasis on those that can be used with the coolants and components of the primary systems of nuclear power plants. 

The considerable length of the lines from the primary circuit to the sampling station in or near the laboratory can cause difficulties in obtaining representative samples for analysis. Since a fraction of the corrosion products in the coolant is in 

In order to avoid the difllculties that can arise in obtaining a representative coolant sample, attempts have been made to develop non-invasive, real-time analysis procedures. Unfortunately, the possibilities of such techniques are limited. For example, chemical composition of the corrosion products, as well as radionuclides without appropriate y emission, are usually not accessible to these procedures. One possible application is the determination of the concentration of particles suspended in the coolant for this task, optical measuring devices have bron developed which are able to operate on-line even at 290 °C, 9 MPa and to count the number of particles with a size down to 1 pm (e. g. Schenker et al., 1992). 

Dose rate measurements yield information about the level of gross y radiation but without giving details as to the specific contributions of the individual radionuclides. They are, therefore, not able to give useful information on the mechanism of contamination buildup. This disadvantage can be overcome by application of non-invasive y-spectrometry measurement using a transportable, shielded, high- 

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