Programmreport 2012 - DORIS - Bundesamt für Strahlenschutz

approaches were considered. It was investigated under which conditions (objective, purpose, exposure situation,
input data quality etc.) radioecological models for exposure calculations can or should be based on deterministic
or probabilistic approaches. The probabilistic modelling of uncertainties was investigated with respect
to minimum requirements concerning the quality of input data and further methodical aspects, and its
reliability was compared to the deterministic exposure modelling.
SUBJECT AREA 06 - EMERGENCY MANAGEMENT
The accidental or intentional release of radioactive materials causes the contamination of urban surfaces, of
buildings and of clothing.The re-suspension of radioactive material is the dominating cause of inhalation exposure
for the first responders and emergency personnel at the incident site. Using a versatile, small-scale
flow channel set-up, wind re-suspension and re-suspension caused by transient or continuous mechanical
forces impacting on urban surfaces were investigated within the project “Experimental determination of
the time dependence of resuspension rates for particle-bound radioactive contamination from
urban surfaces, taking into account varying environmental influences and counter-measures
(3611S60012)“. Well-defined contamination of the test surfaces was prepared in a setting chamber by dry
and wet deposition using aerosolised dry powders of spherical silver particles and sprays of aqueous solutions
of caesium chloride.
The re-suspension rate for surfaces contaminated by wet deposition is 1-2 orders of magnitude lower compared
to dry deposition, irrespective of the re-suspension mechanism. Tests have shown that spraying a water
glycerine solution on the contaminated urban surface is an effective fixing method and the re-suspension rates
can be reduced by a factor of 100. Experiments to investigate re-suspension due to the effect of walking were
performed in a clean room. The fraction of respirable contaminated particles re-suspended from the floor was
in the range between 0.1 and 1 percent with reference to the surface area of the foot sole touching the ground.
A decrease of the re-suspension rate according to 1/n (where n is the number of steps applied to the same
surface) was observed through repeated steps over the same contaminated area. A similar behaviour could
be observed for traffic on public streets. A reduction in speed causes an additional considerable decrease of
the re-suspension.
The program system LASAIR is applied for the assessment of the potential impact after an explosion of a „dirty
bomb“ within the frame of the Defence against Nuclear Hazards. In the course of the application of the program
by authorities and institutions in the area of emergency response some requirements have been unfolded
that are met with this research program. Essentially these are the consideration of building structures and
of orography within the dispersion calculations, the improvement of the mesh size in the close vicinity of the
release and the extension of the application of the program system for the usage in other countries additionally
to Germany. With the research project “Adaption of the systems program LASAIR for actual and extended
tasks in the context of the Defence against Nuclear Hazards (3611S60015)“ these user requirements
have been implemented.
The purpose of the research project “Evaluation of crisis communication in case of a radiological
emergency in the context of the nuclear accident in Fukushima (3612S60020)“ was to develop recommendations
for national authorities that aim to improve the preparation for and response to a nuclear or
radiological emergency with a focus on crisis communication. In a first step, the basic requirements of the relevant
literature in the field of crisis communication were identified and existing planning documents of the assessed
national authorities and organisations were reviewed. In a second step, the experiences of members
of national authorities and relevant organisations with regards to crisis communication in the context of the
Fukushima accident were assessed through the use of semi-structured interviews and the evaluation of internal
review documents. The results of the analysis indicated an overall well-established crisis communication
management system within the relevant national authorities and organisation. For further optimisation, recommendations
for the improvement of crisis communication were derived from the identified issues.
SUBJECT AREA 07 - PROJECTS OF GENERAL IMPORTANCE TO RADIATION PROTECTION
Within the protect “Quantitative radiation risk assessment under consideration of individual exposure
scenarios – update of the radio-epidemiological tables (3607S04570)“ methods have been developed
to express the probability and its distribution that some preceding radiation exposure resulted in cancer
development for a given individual and a given exposure situation (probability of causation). The first version
of the respective computer program ProZES was developed and the methods were implemented. The
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