Primary Shutdown Chemistry guidelines for EDF PWRs: A new approach for better results

摘要

In 2013, EDF has developed new guidelines concerning the PWR primary shutdown. These guidelines are meant as a guide for the power plant. staff, chemists but also operators, in order to optimize refueling and unplanned outages. The document gives a strategy for chemistry and radiochemistry in order to reconcile different and sometimes contradictory objectives: minimizing radiation exposure during outage, shutdown duration and quantity of waste produced while ensuring no or negligible impact on materials and avoiding the risk of forming hazardous gaseous mixtures. The study presented in this paper deals with: 1. The main objectives to be met during outages, 2. The features of new guidelines, 3. The state-of-the art on theoretical developments and studies concerning the behavior of chemical and radiochemical species during transients, The guidelines give recommendations based on a compromise between the current theory of the basic principles of the behavior of chemical and radiochemical species and the feedback collected so far. The recommendations are adapted to each type of outage and each type of radionuclides in order to help the chemistry staff meet the main objectives for a planned or unplanned outage. The main chemical and radiochemical parameters to achieve at different stages and the practical operational measures to apply are presented in order to help the operators to adopt the best strategy and obtain the best possible results.