Boron recycling strategy for Flamanville 3-EPR reactor. Balance between the primary coolant chemistry, the discharges and the economical constraints

One of the chemical options considered in the design of EPR has been the use of enriched boric acid (EBA). This design choice for EPR is supported by several optimisations in terms of system dimensioning and chemistry conditioning. In order to maximise the benefits of EBA and minimise the negative aspects associated with its cost a recycling strategy for Flamanville 3 EPR reactor should be established taking into account: The environmental impacts of boron. The pollution accumulation in the primary coolant. The operating constrains. During the design stage of EPR, EDF has studied several options in order to optimize the boron recycling with the objective of limiting the discharges and the impacts on the primary coolant chemistry due to the potential build up of pollutions such as the silica. Modelling developments and calculations have been carried out leading to better understanding the boron and pollution transfer through the different EPR systems as a function of operating conditions, chemical specifications and water movements. These parametrical simulations provide a mapping of the boron as well as the pollutions in the different systems during a specific cycle and all through the life of the reactor. This paper describes the role of the different systems contributing to the boron management and the modeling results enabling to estimate the boron discharges and the pollution accumulation as function of the operating constrains. This study constitutes a useful tool to decide the actions to apply for allowing the boron recycling preventing the pollution concentrations limits and to determine the countermeasures if the specifications thresholds are exceeded. (author)