REDUCTION IN AMBIENT GAMMA DOSE RATE FROM RADIOCESIUM DUE TO SNOW COVER

Area of Science:

• Environmental Science
• Radiation Physics
• Radiological Protection

Background:

• Radioactive contamination in Fukushima Prefecture necessitates monitoring environmental radiation.
• Snow cover is a common environmental factor that can influence radiation measurements.

Purpose of the Study:

• To investigate the impact of snow cover on ambient gamma dose rates.
• To quantify the reduction in dose rates based on snow characteristics.

Main Methods:

• Field measurements of ambient gamma dose rates were conducted in Fukushima.
• Snow depth, density, and snow water equivalent were measured.
• Gamma-ray flux density distributions were analyzed.

Main Results:

• Ambient gamma dose rates decreased with increasing snow depth.
• Dose rate reduction varied between fresh and granular snow due to density differences.
• Snow water equivalent was a key parameter, with dose rates reducing to 0.6 and 0.5 at 4 and 8 g/cm2, respectively.
• Primary gamma rays showed greater reduction than scattered gamma rays.

Conclusions:

• Snow cover significantly attenuates ambient gamma dose rates.
• Snow water equivalent is a critical factor for assessing radiation shielding by snow.
• Understanding these variations is vital for accurate environmental radiation monitoring in snowy, contaminated regions.