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, energydependent response of the rem meter was not considered. To address this discrepancy, the absolute energydependent 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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