An Investigation of the Mechanism of IGA/SCC of Alloy 600 in Corrosion Accelerating Heated Crevice Environments: Topical Report - Results for Mod of Heated Crevice - 08/18/1999 - 08/31/2000

[摘要] A pressurized water reactor (PWR) steam generator transfers heat from the primary water, heated in the reactor core, to the secondary coolant system. These are shell and tube heat exchangers having the primary water from the reactor inside the tubes and with steam generation on the shell side. This design generates steam on the OD side of the Alloy 600 (or Alloy 690) steam generator tubes, which leads to the concentration of impurities (referred to as hideout) in occluded regions on the tubes. Of major concern is the crevice formed by the tube/tube support plate (T/TSP) intersection. The restricted mass transport in the small crevice volume prevents the species, which concentrate during the generation of steam on the OD of the tube, from quickly dispersing into the bulk water. The presence of a porous magnetite corrosion product from the support plate and deposits, originating from the feed and condenser systems, in the crevice further restricts mass transport, enhancing the concentrating process. This flow restriction leads to the concentration of impurities from the steam generator water by a thermal hydraulic mechanism.

[发布日期] 2000-11-01 [发布机构] Rockwell Science Center LLC, Thousand Oaks, CA (United States)

[关键词] Corrosion;Alloys;Pwr Type Reactors;Steam Generators;Reactor Cores