Validation of neutron generator yield in a complex shielding facility using MCNP6 and rem-meter response correction

초록

This study presents a methodology for verifying the neutron yield of the DD-108 neutron generator installed in a complex shielding facility. The neutron generator was assumed to be operating at its nominal maximum yield of 1 × 108 neutrons/s, and the neutron dose rate was measured using a calibrated rem meter. The same configuration was modeled with MCNP6 to obtain the neutron fluence at the rem-meter location, which was initially converted to ambient dose equivalent by folding the spectrum with ICRP-74 conversion coefficients. However, the resulting simulated dose rate showed a large discrepancy from the measurement as the complex, energy-dependent response of the rem meter was not considered. To address this discrepancy, the absolute energy-dependent response function of the rem meter was derived and applied to the MCNP6-calculated fluence, yielding a calibrated dose rate that reflects the instrument response. By further considering the specified angular dependency of the rem meter, a reference dose rate was established for a rem meter placed at a given position when the neutron generator operates at its maximum yield. The proposed approach provides a practical framework for confirming neutron generator output using rem meters in realistic shielding environments and offers valuable insight for future neutron-generator yield verification.

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