1. CRTI 07-0103RD: Full Scale RDD Experiments and Models
Dr. Lorne Erhardt Group Leader, Radiological Analysis and Defence Defence R&D Canada – Ottawa
Public Security S&T Summer Symposium 16 June 2009

2. Radiological Terrorism RDD Hazard Overview
Presentation Outline
Radiological Terrorism
RDD Hazard Overview
What are the major hazards?
RDD Experimental Work
What do we need to study, why and what we’re doing.
Full-Scale RDD Experiments and Models
Conclusion

3. Introduction: Radiological Terrorism

4. What is Radiological Terrorism?
Radiological terrorism is the use of radioactive material to cause harm
“Harm” could be a lot of things:
Death
Acute effects: Radiation sickness
Chronic effects: Increased cancer risk
Economic effects: Contamination
Psychological effects
The amount and type of harm that a radiological weapon can inflict depends greatly on the design of the weapon

5. Types of Radiological Weapons
For a radioactive source to be dangerous, it must be put into a configuration that allows people to be exposed to it (accidentally or maliciously)
There are two main types of radiological weapons:
Radiological Exposure Devices
Source deployed in order to irradiate people; Simplest form of radiological attack
Radiological Dispersal Devices
Radioactive sources dispersed by explosive or non-explosive means

6. RDD Experimental Work: Objectives and Relevance

7. Why are we studying RDD effects?
Effectiveness of radiological dispersal devices subject to debate
"Dirty Bombs" Much More Likely to Create Fear than Cause Cancer 
American Institute of Physics,
Radiological attacks constitute a credible threat
Federation of American Scientists,
Strategies to protect first responders, the public and critical infrastructure against RDDs must be made in the planning stage, not in the early period just after an attack.
The development of guidelines for first responders dealing with radiological terrorism incidents requires experimentally verified data on the effects of RDDs.

8. What do we need to determine?
For atmospheric dispersion (and other hazard assessment) codes we need the “Source Term”
Particle size distribution and spatial distribution
We must understand:
Mechanism for material break-up
Melting, vaporization, solid fracture
Energetic mechanisms for spatial distribution
Buoyant rise, fragment throw
Modifications to source term
Agglomeration, shock sintering, secondary aerosolization
Many time and distance scales involved
This all depends greatly on the design of the device

9. Understanding RDD Hazards
Pre-detonation
External hazard, maybe some contamination
Detonation gives:
Small particles “respirable” < 10 µm
Inhalation hazard, cloudshine
Medium/large particles 10 – 500 µm
Contamination/groundshine downwind
Fragments > 500 µm
Shrapnel/groundshine near blast
Longer term hazards
Resuspension, ingestion, skin/wound contamination
Need to understand all aspects to quantify hazard

10. Different stress induced mechanisms result
in different initial particle size peaks
Phase change
Phase change
(vapor)
(vapor)
Phase change
Phase change
(liquid)
(liquid)
Stress
Solid fracture
Solid fracture
(across grain
(across grain
Boundaries)
Boundaries)
Comminution
Comminution
peak
peak
Solid fracture
Solid fracture
(along grain boundaries)
(along grain boundaries)
Solid fracture
Solid fracture
(energy limited
(energy limited
spall
spall ) )
> 100 ? m
Particle Size
Slide courtesy Sandia Labs Final size distribution can be a combination of several of these
Peaks and can be modified by combustion and agglomeration

11. Desired Source-Term Modelling Capability
Desired Capability:
Given a suspect package, take a radiograph
Also, dose rate measurement and isotope ID
Quickly (5 min) model the device to determine potential inhalation and ground-shine hazards
Make a determination on disruption and mitigation techniques (and associated consequences)
Modelling an RDD is difficult, examples:
Disc of ceramic with disc of explosives
Uncertainty in downwind hazard
Local contamination hazard from ballistic fraction

12. High Speed Video: February 2007, Valcartier

13. Regular Speed Video: February 2007, Valcartier

14. High Speed Video: February 2007, Valcartier

15. Regular Speed Video: February 2007, Valcartier

16. Video: Sandia Laboratories

17. RDD Experimental Work: Progress, Results and Impact

18. Full-Scale RDD Experiments and Models
New CRTI Project is a follow-on from CRTI RD “Experimental Characterization of Risk for RDDs”
Most ambitious RDD modelling and experimental program to date
Will provide a unique dataset
Indoor and outdoor explosive tests with coordinated source-term modelling program
Federal Government Partners:
DRDC Ottawa – RAD/FFSE
DRDC Suffield – CTTC
DRDC Valcartier – EM
Health Canada
Natural Resources Canada
Environment Canada
Academic Partners:
Royal Military College
Acadia University
Industry Partner:
International Safety Research
International Participants:
UK Atomic Weapons Establishment
US Sandia National Laboratories
New England Complex Systems Institute

19. Full-Scale RDD Experiments and Models
Indoor Explosive Dispersal Experiments (Valcartier)
Explosive dispersal indoors, non radioactive
Aerosol collection to determine airborne hazard
RDD Modelling Program (Ottawa)
Comprehensive look at existing relevant models
Different models for various time and distance scales
Create tool kit and best practices for combining models
Agent-based modelling approach to cross scales
Outdoor Explosive Dispersal Experiments (Suffield)
Two series of tests in 2011, each three weeks

20. Recent Progress
CAN/UK/US RDD modelling workshop held in November in Albuquerque NM
Input from a variety of subject matter experts
Defined best approaches for both the modelling and experimental programs
Modelling effort has focused on evaluation of existing relevant codes, moving on to best practices for integration
Modelling of experimental configuration is just beginning (Canada and UK)
Experimental parameters defined after last workshop
Safety of experiments is first priority, but must maintain relevance to the RDD problem
Indoor source term experiments to focus on modelling gaps and to test the defined outdoor experiments

21. Conclusions
Radiological terrorism involves getting a radioactive substance into a configuration where it can cause harm
RDDs produce different particle sizes leading to different hazards
To fully characterize the hazard you need to determine the “Source Term”
This is difficult due to the great dependence on:
Device design
Material properties
CRTI RD: Full Scale RDD Experiments and Models is addressing these issues
Extensive experimental program is designed to fill gaps in and validate the modelling effort
International collaboration including UK and US participants
Will result in an ability to quickly evaluate emerging threats
Already has resulted in increased understanding of relevant issues