Activation Analysis in Preparation for a Tungsten Irradiation Experiment at LANSCE

Abstract

To organize the safe handling of activated material, knowing the residual dose rates is crucial. In this work, we present the pre-experiment activation analysis for an experiment in which tungsten blocks are irradiated by 800-MeV protons. In this analysis, we use the Monte Carlo N-Particle (MCNP) code for radiation transport, Attila4MC for unstructured mesh generation, and Activation in Accelerator Radiation Environments (AARE), including CINDER2008, for activation analysis. If the tungsten blocks must be removed within a day after the experiment, then exposure to personnel entering the room must be reduced. One exposure-reduction strategy is to add carbon steel shielding around the tungsten blocks, efficiently reducing the dose from the activated tungsten. However, the shielding becomes activated itself during irradiation: ⁵⁶Mn is the dominant contributor for short decay times. The actual schedule at the time of the experiment allowed sufficient cool-off time for the tungsten in the room so that additional shielding was not necessary. A less rigorous comparison of the calculated values with the post-experiment measurements showed reasonable agreement.

Keywords:

• Spallation
• tungsten
• MCNP
• shielding

Acknowledgments

This research used the resources of the Spallation Neutron Source STS Project at ORNL. ORNL is managed by UT-Battelle LLC for the DOE Office of Science, the single largest supporter of basic research in the physical sciences in the United States.

This paper was authored by UT-Battelle LLC under contract no. DE-AC05-00OR22725 with DOE. The U.S. government retains and the publisher, by accepting this paper for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this paper, or allow others to do so, for U.S. government purposes. DOE will provide public access to the results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was performed, in part, at LANSCE, a National Nuclear Security Administration User Facility operated for DOE by Los Alamos National Laboratory (contract 89233218CNA000001).