Eden NE has been commissioned by EDF Energy Nuclear Generation Limited (EDF) to undertake marine dispersion modelling for several Advanced Gas-cooled nuclear Reactor (AGR) sites. This modelling considers how aqueous radioactive effluent could be discharged during decommissioning. It compares a range of alternative discharge arrangements and scenarios (including variations in water and effluent pumping rates, discharge locations and discharge tidal windows). The most relevant scenarios for each station were agreed with the site engineering and environmental safety teams. This modelling informs any future decision making and supports discussions around BAT assessments that will be required to vary the sites' environmental permits to allow the new discharge arrangements.

The models were developed at Eden NE, using GoldSim software, with a view to improving on the spatial and temporal resolution available in PC-CREAM 08, which was developed by the UK Health and Safety Agency (UKHSA) for the assessment of routine discharges. PC-CREAM 08 has a temporal resolution of 1 year, while our model works on time steps of 10 minutes. Our model also represents the local marine features in more detail than PC-CREAM 08.

We have completed the modelling for one site. We are currently undertaking similar work for three other sites.