The effects of local control station design variation on plant risk

A human factors analysis was performed to assess how selected modifications to local control stations (LCSs) in nuclear power plants affect both human performance and plant risk. Modifications in the design of individual control panels and changes in functional centralization were considered. The analysis methodology was accomplished in four stages. First, a list of LCS human engineering design deficiencies was developed using data collected from a variety of sources including visits to nuclear power plants. From these data, a set of potential upgrades were defined to correct the deficiencies. Second, the effects of the upgrades on human error probabilities (HEPs) were determined using a computer-based methodology for soliciting expert judgment. Third, the HEPs were propagated through a plant probabilistic risk assessment, and new core melt frequencies were established. A preliminary, scoping value-impact assessment was performed to evaluate the regulatory need for further review of possible action to improve the human factors engineering aspects of local control stations. The results indicated that implementation of both types of upgrades would improve human performance and lower risk, but that only the panel design improvements would be cost beneficial