Vertical variations of flux parameters in irradiation channels at the TRIGA Mark II reactor of Pavia

Production and characterization of 111Ag radioisotope for medical use in a TRIGA Mark II nuclear research reactor

Radio Pharmaceutical Therapy (RPT) comes forth as a promising technique to treat a wide range of tumors while ensuring low collateral damage to nearby healthy tissues. This kind of cancer therapy exploits the radiation following the decay of a specific radionuclide to deliver a lethal dose to tumor tissues. In the framework of the ISOLPHARM project of INFN, ¹¹¹Ag was recently proposed as a promising core of a therapeutic radiopharmaceutical. In this paper, the production of ¹¹¹Ag via neutron activation of ¹¹⁰Pd-enriched samples inside a TRIGA Mark II nuclear research reactor is studied. The radioisotope production is modeled using two different Monte Carlo codes (MCNPX and PHITS) and a stand-alone inventory calculation code FISPACT-II, with different cross section data libraries. The whole process is simulated starting from an MCNP6-based reactor model producing the neutron spectrum and flux in the selected irradiation facility. Moreover, a cost-effective, robust and easy-to-use spectroscopic system, based on a Lanthanum Bromo-Chloride (LBC) inorganic scintillator, is designed and characterized, with the aim of using it, in the future, for the quality control of the ISOLPHARM irradiated targets at the SPES facility of the Legnaro National Laboratories of INFN. ^natPd and ¹¹⁰Pd-enriched samples are irradiated in the reactor main irradiation facility and spectroscopically characterized using the LBC-based setup and a multiple-fit analysis procedure. Experimental results are compared with theoretical predictions of the developed models, showing that inaccuracies in the available cross section libraries prevent an accurate reproduction of the generated radioisotope activities. Nevertheless, models are normalized to our experimental data allowing for a reliable planning of the ¹¹¹Ag production in a TRIGA Mark II reactor.

Developments of the k0-NAA measurement model implemented in k0-INRIM software

The k0-INRIM software is a computer program that was recently developed to automatically evaluate combined uncertainty while performing mass fraction measurements adopting the k0-standardization method of Neutron Activation Analysis. In this paper, significant developments of the adopted measurement model, following a complete revision of the detector characterization procedure, are reported. In particular, the efficiency ratio between monitor and analyte γ-emissions accounts for conversions between counting positions, extended sample geometry and self-absorption. In addition, true-coincidence summing, neutron flux gradient, moisture and blank corrections are included in the model. The developed measurement model is implemented in the latest k0-INRIM release; this greatly improves flexibility of the software in most of the common situations encountered in routine analysis without losing its inherent characteristic focused on uncertainty evaluation through propagation of covariances via sensitivity coefficients. A performance test was carried out by measuring the Au mass fraction of a cylindrical sample prepared from electronic waste material. Results obtained by counting the sample at different positions with respect to the detector end-cap are presented.