1. Radiological Assessment of Radioactive Contamination on Private Clothing
F. Schartmann, S. Thierfeldt
Brenk Systemplanung GmbH, Aachen
Portoroz, 19. April 2002

2. Overview Introduction
Source terms for contamination on private clothing
contamination mechanisms
types of contamination and source term
nuclide vectors
description of scenarios
Results
dose calculations
comparison with dose criteria
Additional probabilistic assessment
Conclusions
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

3. Introduction Contamination on private clothing:
in rare cases of persons leaving the controlled area of a German nuclear installation
Radiological consequences:
for these and other persons
Spread of contamination:
investigated by VGB (Essen, Germany) (Technical Association of Large Power Plants Operators)
Radiological assessments:
carried out by Brenk Systemplanung GmbH (Aachen, Germany)
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

4. Source Terms for Contamination on Private Clothing (1)
Contamination mechanisms:
material lock, material which is brought out of the controlled area:
part of the contamination may be transferred to persons
exit of the controlled area:
a particle or surface contamination may remain on the body of a person
small objects:
may bear some contamination and is not detected by the gate monitor
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

5. Source Terms for Contamination on Private Clothing (2)
Types of contamination and source term
surface contamination:
more or less homogeneous on clothing
transferred from liquids or greasy material surfaces
part of contamination transferred to skin or incorporated
reports:
activities up to several 100 Bq Co 60 and distributed over several 100 cm²
radioactive assessment:
activities up to 5 kBq Co 60 distributed over 400 cm²
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

6. Source Terms for Contamination on Private Clothing (3)
Types of contamination and source term
particle contamination:
small pieces of matter, highly insoluble
possess high specific activity
transferred only intact
do not stick firmly to the clothing, may fall off
may be hidden in pockets, pleats or seams for some time
reports:
activities up to 5 kBq Co 60
radiological assessment:
activities up to 50 kBq Co 60
particles with these activities are not inhalable
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

7. Source Terms for Contamination on Private Clothing (4)
Dose Calculations
Co 60
various nuclides
six representative NV
Discussed in the following
NV1 and NV2
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

8. Source Terms for Contamination on Private Clothing (5)
Description of scenarios - surface contamination:
A1: on a jacket over 400 cm², worn 30 days for 5 h daily
A2: on the hand, 5 % ingested, rest remains for 24 h
A3: private clothing, contact with small child, 50 % ingested
A4: on the hand, 50 % transferred (e.g. curtain), external irradiation in the sleeping room
Description of scenarios - particle contamination:
B1: on a jacket, worn 60 days for 5 h daily
B2: on a jacket or shoe, transferred to hand and ingested
B3: private clothing, transferred to furniture, ext. irradiation
B4: spectacles or watch, worn 30 days for 16 h daily
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

9. Results (1) Dose calculations for Co 60 Dose calculations for NV1
max. sum of doses 49 µSv (surf. A3), 1867 µSv (particle B1)
Dose calculations for NV2
max. sum of doses 61 µSv (surf. A3), 1843 µSv (particle B1)
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

10. Results (2) Relevant dose criteria for assessment:
10 to 100 µSv: trivial dose range
negligible
1 mSv: dose limit for members of the general public
acceptable for one or few incidents
6 mSv/a or 20 mSv/a: dose levels for controlled workers
not acceptable for members of the public
Results of the assessment:
surface contamination (activity of 5 kBq):
up to 100 µSv  trivial dose range
particle contamination (activity of 50 kBq):
about 2 mSv  beyond trivial dose range
particle contamination (activity of 5 kBq):
up to several 100 µSv  trivial dose range
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

11. Additional Probabilistic Assessment (1)
varied parameters:
probability that a child would be affected, according to demographical data for Germany
the time a garment is worn
transfer factors to skin or curtain/furniture
transfer factors of surface activity being ingested
distance to the source (external irradiation)
probability distribution for the activity for surface and particle contamination
and others
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

12. Additional Probabilistic Assessment (2)
Example: probability distribution for the activity for surface and particle contamination
Surface Contamination
Particle Contamination
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

13. Additional Probabilistic Assessment (3)
Additional probabilistic assessment - results
Surface Contamination
Particle Contamination
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,

14. Conclusion Comparison of deterministic and probabilistic methods
deterministic calculations are conservative compared to the probabilistic calculations
effective doses of probabilistic calculations are 1/10 of the deterministic calculations
surface contamination:
trivial doses of few 10 µSv up to 100 µSv are unlikely to be reached
particle contamination:
effective doses up to mSv range could be reached rarely
In conclusion
necessary to focus on particle contamination
doses which may pose a health hazard can be excluded
because of detection equipment in German plants
Brenk Systemplanung - Radiological Assessment of Radioactive Contamination on Private Clothing, Portoroz,