Hideout tests in Gravelines 1 and Dampierre 3 units : Water chemistry of nuclear reactor systems

Between the end of 1993 and early 1995, tests were carried out at two French PWRs - Gravelines 1 and Dampierre 3 - to determine whether or not the hideout of sodium is more important than that of chlorides. The tests were also able to compare a sea water cooled unit without copper alloys (Gravelines 1) with a river water cooled unit with copper alloys (Dampierre 3). The final objective of the tests was to ascertain if it is necessary to maintain a low molar ratio of Na/Cl at steam generator blowdown to avoid caustic conditions in crevices and thus tubing corrosion. This paper describes the test programme and outlines the conclusions which were reached.