epr-method (2003) - IAEA Publications - International Atomic Energy ...

Annex
BACKGROUND FOR D VALUES IN APPENDIX 8
AI.1 The Requirements [2] define a dangerous source as one “that could, if not under control,
give rise to exposure sufficient to cause severe deterministic effects”. The requirements go on to
define a severe deterministic effect as one that “is fatal or life threatening or results in a permanent
injury that decreases the quality of life”. Table A8-I provides values for the quantities of material
that, if not controlled, should be considered a ‘dangerous source’.
AI.2 In determining quantities that should be treated as dangerous sources we considered the
reasonable exposure routes or scenarios that could result in human exposures if control over a
source was lost. These scenarios and assumptions were developed taking account of past
experience and relevant concerns such as acts of terrorism.
EMERGENCY EXPERIENCE
AI.3 A review of the IAEA reports involving lost or stolen sources is summarized in table AI-I
below. The table does not include an event involving leaving a 0.13 TBq Ir-192 brachytherapy
source in a patient for 4 days resulting in her death [58].
AI.4 The smallest uncontrolled source, relative to the D values in Table A8-I, to result in an
injury that reduced the quality of life due to external exposure was a 0.12 to 0.16 TBq Cs-137
source [49] This is just slightly larger than the D 1 value of 0.10 TBq for Cs-137 in Table A8-I. The
smallest uncontrolled source that resulted in fatal exposure among the public was a 1.2 TBq Ir-192
source [50]. This is about ten times the D 1 value. The only death from intake was from the intake
of 10 -5 of the very dispersible material in a Cs-137 source [39]. This is one tenth of the intake
fraction assumed in calculation of the D 2 values. Therefore it appears that the criteria for defining
dangerous sources are consistent with the accident experience.
TABLE AI-I SUMMARY OF LOST OR STOLEN SOURCE EMERGENCIES
Emergencies
Emergency Source A 149 (TBq) D 148 1 (TBq) A/D 1 Health Consequences
Istanbul [51] Co-60 23.5 0.03 783
Severe injury - life
threatening
Samut Prakarn [52] Co-60 15 0.03 500 3 deaths
Tammiku [53] Cs-137 7.4 0.1 74 1 death
Goiânia [39] Cs-137 50 0.1 500 4 deaths
Lilo [49] Cs-137 0.164 0.1 1.6 Severe injury
Lilo [49] Cs-137 0.126 0.1 1.3 Severe injury
Yanango [54] Ir-192 1.37 0.08 17.1
Severe injury - life
threatening
Gilan [55] Ir-192 0.185 0.08 2.3 Severe injury
Case 20 [50] Ir-192 1.2 0.08 13.8 8 deaths
Case 37 [50] Ir-192 0.26 0.08 3.3 Severe injury
Case 43 [50] Ir-192 0.3 0.08 3.8 Severe injury
Georgia RTGs Sr-90 1000 4 250 Severe injury- life threatening
148 D 1 for the radionuclide involved
149 Activity (TBq) involved in the emergency.
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