However, a way how the decommissioning funds are collected and used depends on national experience and customs, the funds should be collected before the decommissioning project starts.
There are ongoing discussions on how the funding schemes should be configured. According to  there are three main areas to discuss:
Every decommissioning cost estimation is a aggregation of costs for lowest level activities in the cost estimation structure. The cost estimation structure is a tree based structure built-up from activities in the decommissioning project. When estimating costs it also necessary to create a project plan where starting dates of each activity is configured. The reason is simple - the later the activity starts, the lower dose uptake and waste radioactivity have to be treated, which can have significant impact on cost estimation.
Using AquilaCosting you could achieve very accurate cost estimations because AquilaCosting allows you to configure very detailed inventory database, simulate real waste management and treatment flow and setup project schedule for each cost activity.