determining threat categories and use of d values

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


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


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”


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5

Severe Deterministic Effect

Reduces the quality of life


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


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


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)


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9

D1 Contact In Pocket

2 cm From carrying source in

pocket for 10 hrs


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10

D1 - External (Room Scenario)

1 m

Exposure of whole body for

100 h from source


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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


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12

Other Issues

• Criticality for U-235, Pu and others limiting

• Chemical toxicity note (e.g. UF6)


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)


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


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


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


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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


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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


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


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


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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


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EPR-Method Appendix 4

• Source example page 120

• Radiography cameras are in

threat category III

• Possible severe deterministic

effects if control is lost


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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


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Jurisdiction

UPZ

(Cat II, IV & V)Facility

(Cat I, II or III)

National border


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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)

determining threat categories and use of d values

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