To improve FOIs long range dispersion model PELLO, we have changed the particle deposition algorithm in the model. The model is used to aid the national preparedness for radiological events. The project goal has been to enhance FOI's ability to support the Swedish Radiation Safety Authority, the Swedish Armed Forces and other authorities. Deposition of particles is split into two categories. The first category is dry deposition which is when airborne particles directly hit a solid surface on the ground, e.g. a leaf on a tree, and therefore deposit on it and by that decrease the air concentration. The second category is wet deposition where raindrops, snow, etc. scavenge aerosol particles. Our focus in the project has been to improve the wet deposition process in PELLO by refining the quality of precipitation which is the main parameter that contributes to wet deposition. The previous version of PELLO predicted precipitation from wind updraft and humidity but since the numerical weather prediction models, NWP, feeding PELLO with input data have improved over the years, we now can read precipitation parameters directly from NWP. The precipitation intensity available in the NWP is ground level precipitation. PELLO, however, needs the height distribution of the precipitation since a particle that might be deposited only have a chance of that if the precipitating cloud is above it. The vertical distribution of ground level precipitation is made using the NWP parameters, specific cloud liquid water content and specific cloud ice water content, which both describe the amount of liquid and frozen water in clouds. Furthermore, we have introduced the possibility to use different parameterization schemes for different type of wet deposition i.e. deposition from stratiform or convective precipitation, deposition from snow or rain and the difference between in cloud and sub cloud deposition. We have compared this new wet deposition method with both earlier method but also with deposition measurements after the nuclear power plant disaster in Fukushima, Japan 2011. Deposition with this new model shows good agreement with measured deposition.