THE IN-SITU CALIBRATION METHOD FOR AMBIENT DOSE EQUIVALENT DOSEMETERS

Area of Science:

• Nuclear instrumentation and dosimetry
• Radiation protection and measurement
• Metrology and calibration

Background:

• Ambient dose equivalent (H*(10)) dosemeters are crucial for radiation monitoring in nuclear facilities, but their calibration in metrology laboratories is inconvenient.
• Ensuring the accuracy of these widely distributed dosemeters is essential for both routine operations and emergency preparedness.
• Existing calibration methods require disassembly and transport, posing logistical challenges.

Purpose of the Study:

• To develop and validate an in-situ calibration method for ambient dose equivalent dosemeters.
• To assess the feasibility and accuracy of calibrating dosemeters directly within nuclear facilities.
• To provide a reliable alternative to traditional metrology laboratory calibrations.

Main Methods:

• Design and implementation of an ambient dose equivalent secondary standard ionization chamber.
• Development of a portable gamma ray irradiation facility for on-site calibration.
• Conducting experimental calibrations at five distinct sites within the China Institute of Atomic Energy.

Main Results:

• In-situ calibration factors showed a relative deviation within 5% compared to metrology laboratory calibration factors.
• The combined standard uncertainty for the in-situ calibration factor was determined to be 2.8%.
• The expanded uncertainty (k=2) for the in-situ calibration factor was 5.6%.

Conclusions:

• The developed in-situ calibration method is effective for fixed ambient dose equivalent dosemeters.
• This approach significantly improves the practicality and efficiency of dosemeter calibration.
• The method meets the necessary calibration requirements for ensuring accurate radiation monitoring.