Ensuring Safety with Intrinsic Uncertainties and Unknowns

Abstract

　 Perception of uncertainties and unknowns is the basis for rationale decision-making regarding the nuclear safety. They imply that there may be a lack of knowledge and/or misunderstanding about issues concerned. Control of the uncertainties and unknowns depends on the performance of risk management. Risk governance is a framework to sustain the voluntary risk management process continuously for ensuring safety through time. Defense-in-depth is a philosophy of ensuring safety to prepare for uncertainties and unknowns by an appropriate pairing of prevention strategy and mitigation strategy. Ceaseless efforts and activities for nuclear safety under the risk governance framework are to be delivered to public through communication and dialogue. The risk management strategy supported by the safety and risk culture is a key element of ensuring safety that cannot be separated from uncertainties and unknowns.