Benchmarking MCNP and TRIPOLI with PGNAA measurements

Full text of publication follows. The French Alternative Energies and Atomic Energy Commission (CEA Cadarache), the Forschungszentrum Juelich GmbH (FZJ), and the RWTH Aachen University (RWTH) are involved in a cooperation aiming at characterizing toxic and reactive elements in radioactive waste packages by means of Prompt Gamma Neutron Activation Analysis (PGNAA). The design of an optimized measurement system and the assessment of its performances for realistic scenarios can be conveniently studied by numerical Monte Carlo simulation, provided the model and nuclear data offer a sufficient precision. Previous studies performed with MCNP have shown that when the nuclear data libraries lack of precision, relevant results can still be obtained by performing calculations in multiple steps (by first determining the radiative capture rate, and transporting the induced gamma toward the detector) and by injecting valid gamma-ray production data in-between [1]. In such cases, it is interesting to compare the results obtained with different codes. In the present paper, we propose to compare the MCNP and TRIPOLI codes with measurements obtained in MEDINA (Multi Element Detection based on Instrumental Neutron Activation), which is the new FZJ PGNAA facility [2]. The aim of the measurement campaign is to assess capture gamma rays of toxic elements that can be found in 200 liter waste drums which are expected for geological repository. References: 1) J.-L. Ma, C. Carasco, B. Perot, E. Mauerhofer, J. Kettler, A. Havenith, Prompt Gamma Neutron Activation Analysis of toxic elements in radioactive waste packages, Applied Radiation and Isotopes 70 (2012) 1261-1263. 2) E. Mauerhofer, A. Havenith, C. Carasco, E. Payan, J. Kettler, T. Kring, J.L. Ma, B. Perot, Quantitative comparison between PGNAA measurements and MCNP calculations in view of the characterization of radioactive wastes in Germany and France, CAARI 2012, 22. International Conference on the Application of Accelerators in Research and Industry, August 5-10, 2012, Fort Worth, Texas, USA. (authors)