Chapter 2 – Decontamination of Critical Infrastructure

In the early phase of response, decontamination of affected areas or infrastructure should be limited to those locations that are absolutely necessary to access, utilize, or occupy in order to accomplish the life saving mission. Examples of infrastructure that may need to be decontaminated include public health and healthcare facilities, emergency services facilities, and transportation and other critical infrastructure (e.g., power plants, water treatment plants, airports, bridges, and transportation routes into and out of response areas). Affected infrastructure should be prioritized and radiation exposure rates should be estimated to determine whether postponing decontamination is preferable. Several factors should be considered when assessing the need to decontaminate:

  • The DF zone can involve lethal and non-uniform fallout disposition (‘hot spots’) early in the response. Anyone working in areas with significant fallout contamination will require real-time radiation measurements and a robust, actively managed personal dose-monitoring system.
  • Fallout decays rapidly and it may be preferable to delay decontamination efforts. For every sevenfold increase in time after detonation, there is a tenfold decrease in the radiation rate.
  • Where possible, facilities or locations outside the fallout footprint (which will extend beyond the DF zone) should be used to minimize worker does monitoring and the need for secondary decontamination. These facilities and locations could be available immediately and can be expected to be free of contamination. FEMA Continuity of Operations Program (COOP) guidance and planning resources (http://www.fema.gov/government/coop/index.shtm ) can be used as a template for local emergency preparedness planners and can help them choose appropriate COOP locations that will not be affected by fallout or require decontamination.
  • If decontamination is required in the early hours after a nuclear explosion, local responders, who may have had little or no training in radiological decontamination methods, may be needed to perform these duties.
  • Gross decontamination methods that are effective, fast, and easy to implement should be considered, such as vacuum and water washing technologies.
  • Early in the response, there are few situations where significant gains in avoided dose can be achieved through decontamination as opposed to allowing fallout to decay.
Decontamination efforts should be limited to those locations that are absolutely necessary to use or occupy to accomplish life saving, including emergency infrastructure and infrastructure that might facilitate life saving (e.g., emergency gas line shutdown).
Operational Guidelines
Operational Guidelines are pre-derived levels of radiation (presented as stay times and radionuclide concentrations) that can be compared to field radiation measurements to quickly determine if Protective Action Guides are exceeded and actions for protection of workers and the public need to be implemented. They can be employed to inform decisions on the need for protective actions associated with the selection of decontamination approaches to facilitate life and property saving measures and continued use of critical infrastructure during the early and intermediate phases of response. (See http://www.ogcms.energy.gov for resource information.)

Decontamination of critical infrastructure should be initiated only when basic information becomes available regarding fallout distribution, current and projected radiation dose rates, and structural integrity of the elements to be decontaminated. In this early phase, rather than trying to plan the work in detail, it may be desirable to choose the best decontamination methods based on historical research findings (see References) and available resources and start using them in where necessary. It is important first to estimate how much decontamination is required to use or occupy the areas and for how long these areas need to be used. The Incident Commander, in coordination with State and local officials, must determine what requires decontamination and what level of decontamination is necessary. Consideration should be given to the amount of work and operator exposure the decontamination work will entail to achieve that goal. Natural decay of radioactive contaminants should be maximized and accounted for in the dose estimates. This will help avoid unrealistic expectations of the decontamination effort. If the area requiring decontamination is very large and significantly contaminated, and/or if the goal is a very low dose rate or level of contamination, it may take an unreasonable amount of effort to decontaminate that area by the chosen method.

Decontamination of critical infrastructure should be initiated only when basic information becomes available regarding fallout distribution, current and projected radiation dose rates, and structural integrity of the elements to be decontaminated.

Early decontamination of infrastructure may be termed ‘gross decontamination’ because the purpose should be to remove a substantial portion of contaminant to lower radioactivity in order to facilitate use or occupancy of an asset. Gross decontamination may be best accomplished with the simplest technologies. Effective decontamination methods that are easiest to implement will use equipment and operator skills that are immediately available in an urban setting. These methods include:

  • Vacuuming / vacuum sweeping
  • Fire hosing / rinsing
  • Washing with detergents or surfactants
  • Steam cleaning
  • Surface removal using abrasive media (e.g., sandblasting)
  • Vegetation and soil removal
  • Road resurfacing

In general, more effective methods take longer and require more highly skilled operators. The above methods have been demonstrated to remove 20-95% of existing contamination in various conditions, but many factors must be considered to select the most effective method. Often, combinations of methods will produce better results than any single method. Paraphrasing guidance from an International Atomic Energy Agency (IAEA) technical report, Clean Up of Large Areas Contaminated as a Result of a Nuclear Accident, the following is offered as an initial recommendation for selecting decontamination methods:17

“In general, it is recommended that vacuum sweeping and/or vacuuming be considered an initial decontamination process, especially if the contamination is in the form of dry loose particulate material. Even if only marginal decontamination is achieved, the amount of waste produced is minimal and the process does not fix the contamination to the surface or cause it to penetrate porous surfaces. Use of this equipment in areas of medium to high activity would not be possible unless shielded or remotely operated equipment is available. The use of vacuum cleaning for the inside of urban buildings and smooth building surfaces should be beneficial. Fire hosing is also recommended under controlled conditions, especially on smooth surfaces such as roads and parking lots which need to be cleaned up quickly. However, it should only be used if suitable drainage routes are available and contamination of drinking water does not occur. Fire hosing should also be useful for decontaminating certain types of roofs, buildings and equipment having smooth impermeable surfaces.”

If vacuuming followed by fire hosing is not successful in cleaning up heavily contaminated areas, more aggressive methods such as abrasive cleaning, road planning or paint removal would be required. Moreover, no decontamination method is entirely effective; there will always be some level of remaining contamination. Locations that need more than a 90% reduction in dose rate to be safely occupied are poor candidates for early decontamination. Although it may not be practical to contain all the runoff and collect all waste generated from these early phase decontamination operations, local authorities, including emergency responders, should do their best to reduce the impact on the environment.

Related to decontamination is protective clothing for responders. Responders should be instructed in the care of any protective clothing in their possession and when replacement is needed. Supplies will be extremely limited and in many cases, resupply from local stocks will be impossible. At the minimum, monitoring, cleaning, and re-use should be considered