Design performances and chemistry program supporting the FA3/UK-EPRTMactivity management: experience and modelling balance

Abstract

EPRTM reactor accounts with an evolutionary design that provides the appropriate features to ensure the safety implementation of different chemistry and radiochemistry options. ALARP considerations have been taken into account by EDF-AREVA for making decisions relating to the activity management in the primary circuit of FLAMANVILLE 3-EPRTM and UK-EPRTM reactors.The water chemistry and radiochemistry concept implemented in FA3-EPRTM and UK-EPRTM reactors is the result of an exhaustive selection process based on the balance between the theoretical developments, the laboratory tests and the NPP experience concerning the diverse areas associated with:• The source term identification and characterization: The understanding of the origin and behavior of fission products/actinides, corrosion products and activation products constitutes the essential support for the selection of suitable parameters and criteria to monitor the system integrity, the tramp-uranium and radiation build-up and the discharges to the environment.• The source term quantification: The balance between the baseline data from PWR forerunner reactors and the assessments performed by modelling constitutes the major demonstration of the source term accuracy. This approach ensures that activity risks are understood and can be managed with the EPRTM design options.The EPRTM design options evaluation: The sensitivity analysis results show the influence of the fuel management, the material choice and the chemistry conditioning on several domains such as the activity coolant and the fuel/ex-core crud management.EDF-AREVA demonstrates by means of this process that the design, sizing and chemistry conditioning of EPRTM reactor primary circuit are adapted to guarantee the correct activity management. The methodology developed, based on qualitative and quantitative assessments, intends to propose to the Nuclear Industry several alternatives for evaluating and/or improving the compliance with requirements associated with safety, material integrity, radioprotection and environment.