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R. Khan, S. Karimzadeh, H. Böck, M. Villa:
"Modeling a TRIGA Mark II Biological Shield using MCNP5";
Talk: International Conference on Nuclear Energy for New Europe 2009, Bled, Slovenia; 09-14-2009 - 09-17-2009; in: "Modeling a TRIGA Mark II Biological Shield using MCNP5", (2009), 1 - 8.

The 250kW TRIGA Mark II research reactor, Vienna, is equipped with experimental
facilities inside and outside the reactor core. Outside the core, there are four beam tubes (three
radial and one tangential beam tube), a thermal column and a neutron radiography collimator,
supplying neutrons for irradiation experiments. These experiments include neutron radiography,
neutron tomography, neutron activation and academic training purposes. This paper describes
calculations of the neutron flux density in the thermal column and in one of the selected beam
tubes (i.e. BT-A), using the MCNP5 neutron transport code. To validate these calculations with
experiments, neutron flux measurements using the gold foil activation method were performed on
13 selected positions in the thermal column. After comparison between calculations and
measurements on thermal column, this paper also presents the thermal flux distribution in BT-A
calculated by MCNP5. For this task, the already developed MCNP model for the TRIGA core was
extended to the biological concrete shield including the four irradiation beam tubes and the above
mentioned irradiation facilities. To save computational costs and incorporate the accurate and
complete information for the individual MC particle tracks, the surface source writing
capability of MCNP was applied to the TRIGA shielding model. The variance reduction
techniques were also applied to improve the statistics of the problem and to save
computational efforts.

http://publik.tuwien.ac.at/files/PubDat_186307.pdf