Turbulent forced convection flow of Al2O3/water nanofluid in a single-bare subchannel of a typical pressurized water reactor is numerically analyzed. The single-phase model is adopted to simulate the nanofluid convection of 1% and 4% by volume concentration. The renormalization group k-εmodel is used to simulate turbulence in ANSYS FLUENT 12.1. Results show that the heat transfer increases with nanoparticle volume concentrations in the subchannel geometry. The highest heat transfer rates are detected, for each concentration, corresponding to the highest Reynolds number Re. The maximum heat transfer enhancement at the center of a subchannel formed by heated rods is ~15% for the particle volume concentration of 4% corresponding to Re = 80,000. The friction factor shows a reasonable agreement with the classical correlation used for such normal fluid as the Blasius formula. The result reveals that the Al2O3/water pressure drop along the subchannel increases by about 14% and 98% for volume concentrations of 1% and 4%, respectively, given Re compared to the base fluid. Coupled thermohydrodynamic and neutronic investigations are further needed to streamline the nanoparticles and to optimize their concentration.

Silicon PIN photodiode has recently found broad and exciting applications in the ionizing radiation dosimetry. In this study a compact and novel dosimetry system using a commercially available PIN photodiode (BPW34) has been experimentally tested for diagnostic radiology. The system was evaluated with clinical beams routinely used for diagnostic radiology and calibrated using a secondary reference standard. Measured dose with PIN photodiode (Air Kerma) varied from 10 to 430 μGy for tube voltages from 40 to 100 kVp and tube current from 0.4 to 40 mAs. The minimum detectable organ dose was estimated to be 10 μGy with 20% uncertainty. Results showed a linear correlation between the PIN photodiode readout and dose measured with standard dosimeters spanning doses received. The present dosimetry system having advantages of suitable sensitivity with immediate readout of dose values, low cost, and portability could be used as an alternative to passive dosimetry system such as thermoluminescent dosimeter for dose measurements in diagnostic radiology.

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This paper is aimed at understanding thermohydrodynamic and neutronic characteristics of nanofluids for prospective application to water cooled small modular reactors. Numerical analysis is performed to investigate turbulent convective heat transfer and flow features of Al2O3 nanofluids as working fluid. The Al2O3-water nanofluids of 1%, 4% and 6% by volume have been employed for the numerical simulation resorting to the homogenous fluid assumptions with modified thermophysical properties. Results indicate that the heat transfer increases with nanoparticle volume concentrations by 4.2%–31% as compared against that for pure water. The maximum heat transfer increase at the center of a subchannel formed by fuel rods is 31.29% for the particle volume concentration of 6% corresponding to the Reynolds number of 65,000. It consequently appears promising enough to use nanofluids in small modular reactors. Neutronic and thermohydrodynamic investigations are further needed to streamline the nanoparticles and to optimize their concentration during the normal and abnormal operations.

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