An international journal published by K. N. Toosi University of Technology

Document Type : Research Article


Reactor and Nuclear Safety Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran


‎Routine gamma dosimetry of spent fuels in nuclear power stations is mandatory to manage their storage in dry or wet spent fuel storages‎. ‎Mostly the spent fuel gamma dose rate measurements out of the spent fuel pool is impossible because of the high exposures of the operators‎. ‎Therefore‎, ‎determination of a conversion factor as precise as possible is important that could be applied to convert the measured gamma dose rate inside the water shield to the air values‎. ‎Simulation methods are powerfully applied to investigate the conversion factor variation trends due to different burnup‎, ‎cooling time and irradiation history of the spent fuels‎. ‎The present work uses MCNPX Monte Carlo-based code to determine the trend‎. ‎The obtained results of this computational study showed that the conversion factor would not have any dependency to the cooling times‎, ‎burnup values and irradiation history if the detector is placed at special positions in air or water environments‎. ‎Comparison of the simulation and experimental data showed an acceptable conformity‎, ‎so that the experimental verified the simulation data trend


• Determination of gamma dose rate ratio in air to water helps the air gamma dose rate be estimated.

• The ratio has not any dependency to cooling time at special detector positions in air and water.

• The ratio has not any dependency to irradiation history at special detector positions.


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