Understanding the Radiation Soaking Effect in Neutron Survey Instruments

Area of Science:

• Nuclear instrumentation and radiation detection.
• Metrology and calibration of radiation measurement devices.

Background:

• Neutron survey meters using 3He and BF3 proportional counters exhibit response drift.
• This drift, known as the radiation soaking effect, is characterized by increasing dose rate readings under high-intensity radiation.
• The effect is attributed to charge accumulation on internal insulating surfaces.

Purpose of the Study:

• To investigate the radiation soaking effect in neutron survey meters.
• To identify the cause of response variance between different instruments.
• To explore potential mitigation techniques for the radiation soaking effect.

Main Methods:

• Assessing the magnitude of the radiation soaking effect in various instruments under identical high-intensity radiation conditions.
• Analyzing the physical mechanisms responsible for charge accumulation within the detectors.
• Evaluating existing calibration compensation measures.

Main Results:

• A specific reason for the observed variance in detector response has been identified.
• The study quantifies the magnitude of the radiation soaking effect across different neutron survey meters.
• Understanding of charge accumulation mechanisms has been enhanced.

Conclusions:

• The radiation soaking effect in neutron survey meters is a significant factor affecting accuracy.
• The identified cause of response variance provides a basis for instrument selection and understanding.
• Potential methods for mitigating the effect and restoring baseline sensitivity are discussed.