Application of In-Service Temperature Lowering to Reduce Radioactivity Corrosion Product Deposition on Carbon Steel Piping of BWR Residual Heat Removal System

概要

論文の詳細を見る
Assessment of plant data and experiments on deposition of ion species on carbon steel were carried out in order to develop suitable countermeasures to reduce RHR (residual heat removal) piping dose rate. It was thought that radioactivity deposits on the RHR piping were mainly from radioactive ion species in the coolant and they were enhanced by the dehydration reaction of corrosion products on the piping. From an evaluation for temperature dependence of the dehydration reaction, it was proposed to lower the start-up temperature of RHR operation as a way to reduce radioactivity deposition. Feasibility studies of improved RHR operation were conducted and test operations were carried out in the Shika Nuclear Power Station Unit 1. Application of the improved RHR operation resulted in a temperature reduction from 150°C to 110°C, and a radioactivity deposition reduction on the RHR piping to one-fifth of that in conventional RHR operation. The improved RHR operation has now been applied to more than fifteen Japanese BWRs and significant suppression effects of radioactivity deposition have been observed.
2002-10-25