What are impact types used for?
A risk assessment can be evaluated and assessed based on various impact types. Impact types are defined and weighted based on the degrees of extent and frequency. They are graphically represented in a risk matrix and evaluated in the Risk assessments per impact type evaluation. By default, this evaluation is disabled. To enable it, set the following parameter to true: 
Administration > General > System management > System configuration > Workflow management > Risk Management > Show 'Risk assessments per impact type' evaluation.