Proceedings of the Public Security S&T Summer Symposium 2009

CRTI 05-0014RD

Experimental and Theoretical Development of a Resuspension Database to Assist Decision Makers during Radiological Dispersal Device Events

Project Lead: DRDC Ottawa

Federal Partner: Environment Canada

Other Partners: University of Ontario Institute of Technology, Defence Science and Technology Laboratories, Wehrwissenschaftliches Institut für Schutztechnologien – ABC-Schutz, Délégation Générale pour l’Armement – Centre d’études du Bouchet

Objectives

This project will experimentally and theoretically examine the resuspension capabilities of the facilities and experts from four participating North American Treaty Organization (NATO) countries (Canada, Germany, England, and France). The project is also currently the primary focus for the team of radiological experts reporting to NATO’s Radiological and Nuclear Defence Sub-Group under the Joint Capability Group for CBRN Defence.

Relevance

The main threat in almost every radiological terrorist scenario (e.g., a radiological dispersal device) is from radioactive particles distributed over a wide area. More specifically, the main biological threat is the human ingestion or inhalation of these particles. Thus, in order to fully understand the consequences of an event, radiological experts must understand the process by which deposited particles re-enter the atmosphere. This process, known as resuspension when radioactive particles are involved, is directly analogous to the re-aerosolization of particles that are biological in nature.

Particulate resuspension can be influenced by a variety of natural and man-made factors. Natural factors may include weather and the nature of surface or ground cover, and man-made factors could be vehicle and pedestrian traffic or structures. Radiological experts cannot control all of these factors nor hope to duplicate the myriad of possibilities; however, experiments conducted in controlled and contained environments can allow them to better predict, prepare, and mitigate the possible outcomes of a real radiological event.

Recent Progress and Results

Researchers continued to examine a variety of short-lived radioisotopes with different particle diameters in controlled (i.e., indoor) environments. Researchers at Wehrwissenschaftliches Institut für Schutztechnologien in Munster, Germany, hosted trials using a large wind tunnel to explore the resuspension of particles under multiple surfaces and wind conditions. Canada, the United Kingdom (UK), and Germany participated in this trial. Canadian researchers provided measurements to determine the lift-off time of the contamination. Researchers from the UK and Canada provided measurements of the particle concentration in the air in the wind tunnel. German researchers provided measurements of the contamination concentration on the test plates before and after being in the wind tunnel.

This trial proved to be a success and the project team was able to determine estimates of lift-off time, gathering enough data to further work in the modelling of particles being lifted off surfaces.

Currently, trial plans are being developed for more small-scale studies at DRDC Ottawa with a wind tunnel and large-scale proof-of-concept in Bourges, France, and DRDC Suffield for the summer of 2010.

Impact

The experiments conducted under this project will allow radiological experts to better predict, prepare for, and mitigate the possible outcomes of a radiological event, and provide guidance to field personnel (e.g., military commanders) on protective procedures and the operational constraints for work in contaminated environments.

Author:

Marc Desrosiers, DRDC Ottawa, marc.desrosiers@drdc-rddc.gc.ca

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