| Noblis has developed a risk-based methodology for assessing the threat posed by WMDs and has assisted customers in using that methodology to determine which agents are the threats of greatest concern. These agents of greatest concern are then carried forward for further analysis. |
WMD agents The first step is to select which agents will be considered. Typically, a working group made up of subject matter experts would review the open literature and use their professional judgment to establish an initial list of chemical, biological, radiological, and explosive agents for consideration. As the assessment proceeds, the initial list may be modified to include commercially available materials, or to include agents that are uniquely relevant to the customer's facilities and operations.
Biological agents In April 1985, what subsequently became known as the Australia Group proposed that participating governments impose controls on the export of specific chemicals used in the manufacture of chemical weapons. In 1990, the Australia Group countries recognized an additional need to address the increasing problem of the spread of biological weapons. Subsequently, they published a
list of biological agents and toxins in need of export control.
In 1997, the U.S. Centers for Disease Control and Prevention (CDC) drafted a Select Agent Rule that imposes domestic controls on the transfer of a select group of human pathogens and toxins described in the Code of Federal Regulations (49 CFR Part 73). The
CDC Select Agent list, like the Australia Group agent list, represents biological agents that have the following characteristics:
- Historical precedence as a biological weapon
- Verified or suspected use in offensive weapons research and development
- The potential for nefarious use in acts of terrorism
Biological threat agents can be selected based upon these lists.
Chemical agents
The Chemical Weapons Convention identifies 28 toxic chemicals (or classes of closely related toxic chemicals) in Schedules contained in the Annex on Chemicals; these are broadly termed the “ chemical warfare agents.” However, many other chemicals approach the chemical warfare agents in toxicity. For example, the US EPA currently includes 355 “ extremely hazardous substances” under Section 302 of Emergency Planning and Community Right-to-Know Act (42 USC 116, Sec. 11002(a)(2)). Other lists of toxic industrial chemicals can be consulted as required.
Radiological Agents
Radiological materials of interest can be selected following a review of technical materials that include:
- U.S. Nuclear Regulatory Commission Regulatory Guide 4.16, Monitoring and Reporting Radioactivity in Releases of Radioactive Materials in Liquid and Gaseous Effluents from Nuclear Fuel Processing and Fabrication Plants and Uranium Hexafluoride Production Plants, December 1985; and U.S. Nuclear Regulatory Commission Regulatory Guide 8.34, “Monitoring Criteria and Methods to Calculate Occupational Radiation Doses,” July 1992.
- Thomas, Duncan C. and McNeill, K.G., Risk Estimates for the Health Effects of Alpha Radiation, AECB Research Report INFO-0081, September 1982.
These sources can be supplemented by considering radiological materials and equipment used in industrial and medical applications. Threat agents are selected from these sources based on which agents are most likely to be used against the customer's facilities and operations.
Methodology: Scenarios and criteria
The risk-based methodology for conducting the overall assessment is based upon the principles and guidance found in Mil-Std-882D, Department of Defense Standard Practice for System Safety, 10 February 2000). Both the severity of an event and the likelihood of its occurrence are evaluated as inputs to the threat assessment. This is consistent with the end goal of evaluating risk and selecting appropriate countermeasures to achieve a significantly lower level of risk at the most affordable cost.
The assessment methodology begins with the development of three components:
- Establish plausible scenarios; the threat agent, the amount and form of the agent, the delivery mechanism, where an event occurred in the customer's facility or process, and the intended target are specified as “Scenarios.”
- Establish criteria for evaluating the “ likelihood” of an agent being used to commit a terrorist act in or through a customer's operation or facility.
- Establish criteria for evaluating the “ severity” of the potential consequences of an agent being successfully used to commit a terrorist act.
Once the scenarios and criteria are established, the working group can evaluate each scenario against the criteria.
Determine agents of greatest concern
This methodology is best applied by a working group of experts whose members are drawn from both the customer and Noblis. Customer members of a working group contribute knowledge and experience of their systems and processes. Noblis members contribute specialized knowledge pertaining to the specific agents and develop the systems to document the process. The entire working group collaborates in defining the methodology used in an assessment.
The working group uses the evaluation criteria to develop a threat assessment matrix, which provides a structured, objective approach for evaluating threat agents in terms of the likelihood of their use against the customer and the severity of their consequences if successfully used in a defined scenario. Each threat agent scenario is evaluated for each criterion on an ordinal scale; typically, the scale has five qualitative ratings: high, medium-high, medium, medium-low, and low. These are assigned values of 5, 4, 3, 2, and 1, respectively, for purposes of computing likelihood and severity scores. In order to ensure a consistent and objective evaluation of the threats, the working group should develop a set of rating guidelines for each criterion. Individual working group members evaluate each threat agent scenario against a set of checklist items with associated descriptors. Information concerning all applicable checklist items is incorporated into a supporting discussion, and an overall rating is assigned after comparison with the rating guidelines. In one assessment, 150 structured scenarios covering more than 40 agents were evaluated for each of ten criteria. This approach allows a review and a “scrubbing” of the results to ensure consistency of judgment across the set. In addition, weights are assigned to evaluation criteria. At this juncture, the relative weighting of individual criteria can be subjected to a sensitivity analysis to ensure that the assigned weights are not introducing a systematic error that would skew the results.
The results of the evaluation are then assessed by plotting weighted average Likelihood values along the vertical axis, while the weighted average Severity values were plotted along the horizontal axis. Because the risk associated with each hazard must encompass both the Likelihood and Severity measures, risk is measured as the cross-product of Likelihood and Severity [Risk = Likelihood x Severity]. The Likelihood score for each scenario is multiplied by the Severity score to give a measure of the overall risk posed by the scenario. This calculation creates an ordinal scale ranking of threat agent scenarios for determining the agents of greatest concern to the customer. Those agents and scenarios with the highest scores can then be addressed in the Vulnerability Assessment and Consequence Management exercises.