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IAEA Training in Emergency Preparedness and Response
Module L-010
Determining Threat Categories
and use of D Values
Lecture
L-010: Determining Threat Categories and Use
of D Values
2
Introduction - Requirements (GS-R-2) are
Established for Threat Categories
Threat
Category Radiological Threat
I Severe deterministic health effects off-site
II Warranting urgent protective actions off-site,
deterministic health effects on-site
III No urgent protective actions off-site are warranted,
severe deterministic health effects on-site
IV Minimum level of threat – all countries
V Food contamination due to transboundary
contamination necessitating food restrictions
L-010: Determining Threat Categories and Use
of D Values
3
Overview
The EPR-Method Section 2.2.5 and Appendices
5 and 7 provide tools to help determine the
threat category
This lecture will review these tools
L-010: Determining Threat Categories and Use
of D Values
4
The Safety Requirements (GS-R-2)
• Sets requirements for dangerous sources and defines:
• “Dangerous source” as: “could, if not under control, give rise to exposure sufficient to cause severe deterministic effects”
• “Severe deterministic effect” that: “is fatal or life threatening or results in a permanent injury that decreases the quality of life”
L-010: Determining Threat Categories and Use
of D Values
5
Severe Deterministic Effect
Reduces the quality of life
L-010: Determining Threat Categories and Use
of D Values
6
Need an Operational Definition
• In terms of activity (TBq)
• Must be realistic – not overly conservative
• Understandable by public
• Dangerous must mean DANGEROUS
• Called the D value
L-010: Determining Threat Categories and Use
of D Values
7
D Values have many Uses
• EPR-Method and future guides on emergency preparedness and response based upon:
• Threat categories
• Plain language description of threat
• Response guides
• IAEA assessment of events
• Categorization of radioactive sources • IAEA-TECDOC-1344
• Code of Conduct on safely and security of sources
L-010: Determining Threat Categories and Use
of D Values
8
Two Different D Values
• D1 value is the amount considered dangerous if not
dispersed (encapsulated)
• D2 value is the amount considered dangerous if
dispersed (e.g., ruptured)
L-010: Determining Threat Categories and Use
of D Values
9
D1 Contact In Pocket
2 cm From carrying source in
pocket for 10 hrs
L-010: Determining Threat Categories and Use
of D Values
10
D1 - External (Room Scenario)
1 m
Exposure of whole body for
100 h from source
L-010: Determining Threat Categories and Use
of D Values
11
D2 Dispersed Material
• Inhalation by airborne dispersal (fire – RDD)
• Ingestion
• Inadvertent contamination (e.g. hangs on)
• Intentional – e.g. terrorist contamination of water
supply
• Skin contamination
L-010: Determining Threat Categories and Use
of D Values
12
Other Issues
• Criticality for U-235, Pu and others limiting
• Chemical toxicity note (e.g. UF6)
L-010: Determining Threat Categories and Use
of D Values
13
The D Values (TBq) Methods Table A8-1
Radionuclide D1 D2
H-3 UL 2000
Sr-90 (Y-90) 4 1
Cs-137
(Ba-137m)
0.1 200
Pu-239 1 (criticality) 0.06
U-238 UL UL (toxic note)
L-010: Determining Threat Categories and Use
of D Values
14
Mixture of Radionuclides
iior
orD
Ai
DA,21
21/
If A/D is greater than 1 than it is a dangerous source
L-010: Determining Threat Categories and Use
of D Values
15
Uncontrolled Source Accident History
• Smallest source to cause severe injury
• Cs-137 source 1.2 X D1 value
• Most injuries involved sources 10 X
D1 values
• Smallest to cause death
• Ir-192 source 14 X D1 value
• Most deaths involved sources 100-
500 X the D1 values
L-010: Determining Threat Categories and Use
of D Values
16
Gilan, Iran: Lost And Found Radiography
Source
•0.185 TBq Ir-192
•2.2 X D1
•In pocket for several hours
L-010: Determining Threat Categories and Use
of D Values
17
Threat Assessment by the EPR-Method
Table III pages 20-21 suggests threat categories of facilities and practices based on:
- Reactor power levels
- Spent fuel inventories
- Activity/D value ratios
- Dose rates at 1 meter
- Potential for criticality
- Probability of encountering
an uncontrolled source - Scrap metal dealers
- Border crossing
L-010: Determining Threat Categories and Use
of D Values
18
Table III Pages 20-21 in the EPR-Method
As an example criteria for threat category II if:
• Reactor power level > 2 and < 100 MW(th)
• Spent fuel requiring active cooling
• A/D ratios 10 times the D2 values of material that can be released
• Potential for criticality within 0.5 km of site boundary
L-010: Determining Threat Categories and Use
of D Values
19
Table III Pages 20-21 in the EPR-Method
As an example criteria for threat category IV
• Mobil source dose rates at 1 meter of > 10
mGy/h
• A/D value ratios > 1
• Facilities with a significant probability of
encountering an uncontrolled source
• Scrap metal dealers
• Border crossing
L-010: Determining Threat Categories and Use
of D Values
20
EPR-Method Appendix 4 Page 119
• List typical threat categories for various practices:
• Industrial, medical and scientific use
• Sealed sources
• Fuel cycle
• Reactors
• Transport
• Other
L-010: Determining Threat Categories and Use
of D Values
21
EPR-Method Appendix 4
• List typical threat categories for various practices
Examples - page 119
• Hospital - possible category III
• Severe deterministic effects
possible on site from
medical sources
• e. g. from teletherapy unit
L-010: Determining Threat Categories and Use
of D Values
22
EPR-Method Appendix 4
• Source example page 120
• Radiography cameras are in
threat category III
• Possible severe deterministic
effects if control is lost
L-010: Determining Threat Categories and Use
of D Values
23
Areas are also Associated with a Threat
Category - EPR-Method - Table IV
Threat category Local jurisdiction
I Urgent protective actions in PAZ/UPZ for
category I
II Urgent protective actions for PAZ for
category II
III Emergency services for category III facility
IV All
V With farming or food processing near
category I or II facility
L-010: Determining Threat Categories and Use
of D Values
24
Jurisdiction
UPZ
(Cat II, IV & V)Facility
(Cat I, II or III)
National border
L-010: Determining Threat Categories and Use
of D Values
25
Where to Get More Information
• IAEA, Preparedness and Response for a Nuclear or Radiological Emergency, Safety Standards Series No. GS-R-2, IAEA, Vienna (2002)
• IAEA, Method for Developing Arrangements for Response to a Nuclear or Radiological Emergency, EPR-Method, IAEA, Vienna (2003), (Updating IAEA-TECDOC-953)