PWR secondary side iron transport during transients - T01-3

Corrosion product transport to the secondary side of PWR steam generators (almost entirely iron in units without significant copper components) can cause major operational issues, potentially leading to lost power generation due to heat transfer surface fouling, tube degradation due to concentration of ionic impurities in deposit related crevices, or accelerated fatigue or erosion damage due to modification of internal fluid flow characteristics. Technologies have been developed to reduce the creation of corrosion products (amines for pH control), decrease their deposition in the steam generators (polymeric dispersants), or efficiently remove them during outages (chemical cleaning). However, secondary side sludge management remains a costly aspect of PWR operation. Prior work has indicated that a significant portion of the corrosion products transported during a cycle can occur during startup (up to 80% by early estimates, but up to 20% in more recent findings). Due to an increase in flexible power operations (FPO) at some units and an expectation of increased FPO operation at others, there is a concern that iron transport to the steam generators may be significantly increased due to the increased number of power transients, potentially behaving in a similar manner to start-ups. In this work, the EPRI PWR Chemistry Monitoring and Assessment (CMA) database was leveraged to evaluate the iron transport associated with 110 beginning of cycle start-ups, 71 mid-cycle outage start-ups, and 470 FPO-type power changes (651 power ascension events in total). This paper presents the methodology used to characterize the iron transport associated with each of these transients and provides a review of the results and the conclusions drawn from this robust data set. (authors)