Alternatives to NIST Cf-252 Iirradiations for Transfer Calibration of S-32 Neutron Monitors

¹ Sandia National Laboratories, Radiation Modelling and Metrologi, Albuquerque, NM 87123, USA
² The University of Texas at Austin, Nuclear Engineering Teaching Laboratory, Austin, TX 78758, USA

^* Corresponding author: dwvehar@sandia.gov

Published online: 11 November 2024

Abstract

Gas-flow proportional counting systems are used by the Radiation Metrology Laboratory (RML) at Sandia National Laboratories for reactor fluence monitoring with the ³²S(n,p)³²P reaction. Calibration of these systems has traditionally been accomplished by fluence-transfer irradiations at the NIST ²⁵²Cf facility. Such calibrations have become increasingly difficult as the NIST ²⁵²Cf source decayed to unusable levels. To minimize the risk to the testing programs from an inability to properly calibrate these systems, the RML has developed two alternative calibration techniques: 1) development and implementation of certified ³²P sources for activity calibrations and subsequent calculation of neutron fluence, and 2) direct counting of non-certified reactor-irradiated sulfur pellets by liquid scintillation counting to determine ³²P activity for the subsequent calibration of gas-flow proportional counters. Preliminary comparisons show that the several calibration methods are capable of overall uncertainties within about 5 percent.