(216e) A Portable Remote Chemical Analyzer for Identification of Deposits at Palo Verde Nuclear Generating Station

Abstract-- Reactor coolant pressure boundary leakage in pressurized water reactors leaves a white boric acid residue that is corrosive to reactor components. However, not every white deposit found in a PWR is boric acid, and identification of unknown deposits can be crucial in determining if an active leak exists. Current methods for identifying the source of unidentified deposits require a sample to be removed and analyzed using radiometric techniques. This approach is time-consuming, requires potential exposure of personnel to radiation, suffers from false positives, and may not be possible in locations that are inaccessible or where only small amounts of deposits exist. A new technique based on Raman spectroscopy allows in-situ analysis and positive identification of boric acid residue. This technique can also determine the state of hydration of the boric acid which will help understand the nature of the source of the residue. The spectroscopic analyses of other common materials that may be mistaken for boric acid are also presented.

Palo Verde Nuclear Generating Station (PVNGS) has identified a need for a field test to determine unequivocally if an unidentified deposit is boric acid, either from a reactor coolant solution (RCS) pressure boundary leak or a spill. Formerly, potential pressure boundary leaks were identified by visual identification of white deposits, followed by laboratory confirmation using radiometric techniques. Radiometric techniques, however, do not determine that a white deposit is RCS, which is predominantly boric acid, and such techniques are subject to false positives and errors in interpretation. Also, there is significant cost associated with removal of a sample from the suspected leak site and laboratory analysis, both in time and increased radiation exposure to personnel.

PNVGS and Symphotic TII have developed a technique for in-situ analysis that gives positive identification of boric acid deposits without requiring removal of a sample for laboratory analysis.

This project won a 2006 NEI, Top Industry Practice Award.