The effectiveness of titanium additions on mitigating FAC under PWR feedwater conditions

Authors : B. Clark¹, A. Feicht², A. Justason³ and D. Lister²

Companies : ¹ Electric Power Research Institute, Charlotte, NC, USA
                       ² University of New Brunswick, Fredericton, NB, Canada
                       ³ Centre for Nuclear Energy Research, Fredericton, NB, Canada

Countries : Canada, USA 

ABSTRACT :

Titanium as an additive in CANDU_® primary coolant has been shown to reduce the rate of FAC of the carbon steel feeder pipes that direct the coolant from the core to the steam generators.  The mechanism apparently depends upon the incorporation of Ti into the magnetite oxide that normally forms on the steel in high-temperature water.  Localised corrosion in steam generator crevices has also been mitigated by additions of Ti, apparently by a similar mechanism.  It would seem possible, therefore, that Ti as an additive would mitigate FAC of carbon steel piping in PWR feedwater systems.  To explore this concept, an experimental program sponsored by the Electric Power Research Institute has utilised a high-temperature water loop to evaluate the effectiveness of adding Ti-based compounds to simulated PWR feedwater.  On-line tubular probes measured corrosion directly at system conditions by monitoring the FAC-induced thinning of the tube walls with an electrical resistance technique.  In the program, three compounds were tested in the loop, each at a concentration producing several μg/kg equivalent of elemental Ti at the probes.  Coolant chemistry conditions were: ammoniated water at pH_25°C of 9.2, hydrazine at 40 ppb and temperature of 140°C.  For each additive, plots of probe internal radius against time showed directly the progression of FAC, and comparison with periods before the addition demonstrated any mitigating effect of the Ti.  Indications of the effects of coolant velocity on FAC during Ti addition were obtained by varying loop pumping rates.  Destructive examination of probes after exposure revealed any change in surface appearance and constitution brought about by the additive. The paper describes the experiments and results and assesses the possibility of using Ti compounds for mitigating FAC in feedwater systems in operating PWRs.

Speaker Biographical Information

        Derek H. Lister

Derek Lister has spent most of his career as a scientist researching various aspects of the nuclear industry.  After graduating with a B.Sc. and M.Sc. in Chemical Engineering at the University of Manchester in England he joined the English Electric Company, where he studied heat transfer and pressure drop in gas-cooled reactors.  After a few years, he entered the University of Leicester as a Research Fellow in Physical Chemistry and obtained his Ph.D. before joining Atomic Energy of Canada Limited at the Chalk River laboratory.

There, he became an expert in the chemistry and corrosion of water-cooled reactors, progressing from Section Head to Senior Scientist and Manager of the System Chemistry and Corrosion Branch.  In 1992, he was appointed as professor and holder of the Industrial Research Chair in Nuclear Engineering at the University of New Brunswick (UNB) in Fredericton.  He became Chairman of the Chemical Engineering Department in 2000 but retired from that position in 2005.

Currently, as Professor Emeritus but still holding the Research Chair, Dr. Lister continues his research unabated.  His technical interests are still centred on water coolant technology of nuclear reactors, a subject in which he continues to publish extensively.  He is recognised internationally as an expert in the field and is frequently consulted by industry and government institutions.

He is a member of the Canadian Nuclear Society, the Nuclear Institute (U.K.), the Institution of Chemical Engineers (U.K.) and is a Fellow of the Chemical Institute of Canada and a Chartered Engineer in the U.K.  In 1995, he was appointed to the R&D Advisory Panel of Atomic Energy of Canada Limited, becoming Vice-Chair in 2002 and Chairman in 2004, in 2002 he was appointed to the Advisory Council of the Nuclear Waste Management Organization in Canada and in 2007 he became a member of the External Advisory Panel to the GenIV initiative of the Canadian Government.

Given any spare time he enjoys hiking and tennis and, in the winter, cross-country skiing and snowshoeing.  He is an amateur artist, dabbling in drawing and painting, and an avid reader of French and English literature.