In subsequent iterations of the risk assessment, more data is required, assumptions become more refined, and calculations may become more complicated. These subsequent iterations are each called detailed Site Specific Risk Assessments (SSRA). The iterations/refinements to the risk assessment continue until it is apparent that:
a) the risk is negligible/tolerable, or
b) there is a verified unacceptable risk, the risk assessment can not be refined further, and it warrants mitigation and management.
The refinement provides compelling evidence that elevated/unacceptable risks warrant mitigation.