A Comprehensive Approach to Protecting Nuclear Materials and Facilities Against Terrorist Threats

More than ten years after the 11 September attacks in the United States, the terrorist threat continues to evolve. Strategies for protecting nuclear facilities and nuclear materials from sabotage and theft must be flexible enough to rapidly accommodate changes in the threat environment, yet also must be sufficiently detailed to provide assurance that they will be effective against a range of specific scenarios. Also, after the Fukushima accident, concerns have grown about the potential for “cliff-edge” effects, in which challenges such as flooding at a nuclear plant can lead to catastrophic consequences if the plant’s design basis is exceeded by only a small margin. Protective strategies for nuclear plants against terrorism should also be resistant to “cliff-edge” effects, yet there is insufficient attention to this issue in the security realm. Lessons can be drawn from the so-called “B.5.b” measures required by the U.S. Nuclear Regulatory Commission (NRC) after 11 September to provide backup means to prevent or mitigate core damage at nuclear plants in the event of an aircraft attack that disables ordinary mechanisms for core cooling. The B.5.b. measures were specifically intended to cope with the aftermath of an aircraft attack, but might not have been usable following a different or more severe mode of attack. In addition, the B.5.b measures may not have been effective even for their intended purpose because the NRC did not require detailed procedures to govern how they would be implemented after an attack, or detailed inspections to ensure that B.5.b equipment would be operable. An approach that is both broader and deeper is required to provide an adequate level of security. INTRODUCTION One of the major goals of the Obama administration going into the 2010 Nuclear Security Summit was to “lock down” all vulnerable nuclear weapon-usable materials by the end of 2013. But what does this mean in operational terms? The gold standard for “locking down” nuclear facilities against terrorist attacks should be defined by a multi-step approach. First, credible design basis threats (DBTs) must be formulated, with adequate conservatism to allow for uncertainties in the threat environment. Second, facility operators should develop rigorous physical protection plans with the objective of providing high assurance of protection against the appropriate DBT for each class of facility. (The grading of security requirements for different threats should be applied, provided that there is rigorous technical assessment to support