According to Jewkes (2004), actuarial discourse means a type of discourse of social control that has moved from reactive to proactive (p. 179). I.e., CCTV is designed to stop problems before they start.
According to Lyon (2009), "Actuarial justice has to do with "statistically-based standards for identifying the dangerous" [Richard Ericson 2007, Crime in an Insecure Wold], but today it is partially superseded by the logic of 'precaution' just because of the growing gray of uncertainty, especially in relation to anti-terrorism" (p. 102).
References:
Jewkes, Y. (2004). Media & crime: Key approaches to criminology. Thousand Oaks: Sage Publications.
Lyon, D. (2009). Identifying citizens: ID cards as surveillance. Malden: Polity.