Vital Area Determination Techniques at Nuclear Power Plants

This paper describes the vital area determination programs being conducted at the Los Alamos National Laboratory to support the Nuclear Regulatory Commission (NRG) in evaluating nuclear power plant licensees' compliance with safeguards/security requirements. These projects, the Vital Area Analysis (VAA) Program and the Vital Equipment Determination Techniques Research Study (VEDTRS), are designed to identify a plant's vital areas and to develop protection strategies against adversary threats in nuclear power plants. A methodology to deal with large complex systems using a systematic risk assessment approach was developed at Los Alamos, and to date, the Laboratory has used it to perform VAAs for nearly all commercial nuclear power plants. The VEDTRS is basically a research effort with an emphasis on upgrading the current Los Alamos VAA modeling schemes and practices. Major elements in the VEDTRS include reexamining the VAA assumptions, performing best-estimate safety code analyses for transients and loss-of-coolant accidents, interacting with NRC's ongoing safety programs, and assessing the effects of using recommended new schemes on the Los Alamos VAAs. The VEDTRS supported the 1985 NRC Vital Area Committee (VAC) by validating VAA assumptions and developing guidelines for implementing the VAC's recommendations. The results of several VEDTRS research topics have led to recommendations for modeling changes in the current Los Alamos VAAs and, as a result, would have a major effect on the vital location designation and protection strategies at a nuclear power plant.