Planning for the Worst in Washington State: Initial Response Planning for Improvised Nuclear Device Explosions

Abstract

Since 11 September 2001, improvised nuclear devices have become recognized as an important radiological threat requiring emergency response planning. Although Protective Action Guidance is well established for fixed nuclear facilities, correspondingly well-developed guidance does not exist for nuclear explosions. The Washington State Department of Health has developed preplanned Protective Action Recommendations for improvised nuclear device explosions. These recommendations recognize the need for advice to the public soon after such an event, before significant data are available. They can be used before significant outside support is available locally, and reference observable effects so people can use them if communications were disabled. The recommendations focus on early actions (24-48 h) and place priority on actions to avoid deterministic health effects due to residual fallout. Specific emphasis is placed on determining recommendations for evacuation, as well as the extent of the area for sheltering. The key recommendations developed for an initial public response are: (1) if there is ready access to robust shelter such as an underground basement or interior spaces in a multi-story structure, immediate sheltering in these areas is the best action, regardless of location; (2) if robust shelter is not available, and if fallout is observed in the area, then evacuation is the best general recommendation for locations within 16 km (10 miles) of the explosion; and (3) beyond 16 km (10 miles), the generally recommended protective action is to shelter in the best-protected location which is readily available.

Analyzing Evacuation Versus Shelter‐in‐Place Strategies After a Terrorist Nuclear Detonation

“…Recommendations include evacuate unless a quick evacuation is not possible, ( 30 ) shelter in place, ( 31 ) evacuate only people in the 24‐hour dose‐integrated median lethal dose range (a 5‐mile‐long oval), ( 32 ) and if the shelter transmission factor is 0.7, evacuate if the 24‐hour integrated dose is > 100 rem (i.e., within 10 miles). ( 33 ) Two recent studies ( 27,28 ) perform a more detailed analysis of shelter versus evacuation strategies. These models employ a more complicated effects and fallout model by accounting for urban terrain and non‐Gaussian plumes generated by altitude‐dependent wind direction (while these refinements would be very valuable for aiding in postevent situational awareness, they are not required for assessing shelter versus evacuation strategies prior to an event, as long as—as noted in Reference 28—the idealized Gaussian plume is not exploited for evacuation purposes).…”

Simulated nuclear contamination scenario, solid cancer risk assessment, and support to decision

“…The consequences of an explosion of an IND might transcend political and economic boundaries [11,13]. Risk perception and risk communication are major concerns since they are crucial particularly during the initial phase of response.…”

“…The scenario under evaluation in this work considers an explosion of an IND at a populated urban site. Although preparedness is the most important phase toward an effective response [11], special attention was drawn to provide fast information about future detriments for the public due to potential radiation exposure and responders. Signifi cant amount of radioactive material is expected to be deposited on the soil after the IND explosion.…”

Key Response Planning Factors for the Aftermath of Nuclear Terrorism

“…Moving away from the centerline when evacuating the area provides the lowest possible exposure, thus the simplified "lateral evacuation" guidance that is often reported in literature. 32,33 Although the Gaussian fallout pattern can occur, it is not a good planning assumption as more complex fallout patterns are more challenging and also frequently occur, particularly in coastal areas. This was recognized by FEMA in the 1982 NCRP symposium on The Control of Exposure of the Public to Ionizing Radiation in the Event of Accident or Attack; "Uncertainties in fallout modeling, coupled with uncertainties about weather, wind shear, and attack patterns make fallout prediction almost useless. "…”