(54ar) Human Performance in Extreme Weather Events

Hurricane Harvey and its flooding aftereffects led to loss of both offsite and emergency back-up power at the Arkema plant in Crosby, TX, which in combination with reduced site accessibility and availability of operations personnel, led to the plant’s inability to keep their products Luperox (organic peroxides) sufficiently cooled, causing the thermally unstable and heat sensitive compounds to undergo spontaneous decomposition, resulting in fires and explosions.

Recent efforts in the nuclear power industry to assess high winds (HW) effects through PRA/QRA and to develop coping strategies for loss of power scenarios may provide useful insights to the chemical process industry, particularly in the area of human reliability analysis (HRA).

High wind-induced initiating events considered in HW PRAs include tornadoes, hurricanes, and straight-line winds (i.e., thunderstorms and extratropical storms). Depending on the location of the site, some of these types of storms may be below the frequency threshold for consideration.

The HW HRAs performed by the authors included procedure reviews and operator interviews to glean insights about operator response during a high wind event. Topics for HW HRA operator interviews have generally included:

• General operator response to a high wind event in the main control room
• Pathways inside protected structures and potential high wind event impacts
• Feasibility of outdoor activities after the storm has passed
• Timing of performing the post-storm damage assessment

The timing associated with the action is a key element in the development of the human failure events (HFEs) considered. For high winds HRA, the duration of the storm plays an important role in the development of HFEs. Site-specific data are collected to determine a mean duration for each of the types of high wind initiators. Since tornadoes, hurricanes, and straight winds vary greatly in duration, the feasibility of HFEs must be considered for each type of high wind event. An HFE may be feasible for one type of initiator, but not another. For example, since tornadoes may only last a matter of minutes, but hurricanes may last several hours, a long-term operator action that occurs outdoors may be feasible for a tornado but not a hurricane. Conversely, advance warning of hurricanes provides the opportunity for site preparation that the sudden occurrence of tornadoes does not permit.

In addition, in cases where there is an extended loss of AC power, special procedures and equipment may be utilized as part of the Flexible Response to Extended Loss of All AC Power (FLEX) initiative. Since the primary impact of a high wind event is a loss of offsite power, implementation of FLEX could become necessary if onsite power sources (e.g., diesel generators or other back-up power methods) are also unavailable. Modeling operator actions for implementation of FLEX as part of external events PRAs will also be discussed in this paper.