Abstract:
Absorbed dose rates at 38 locations along the coastline from Hambantota to Dondra, at 1
m above ground were measured using a portable digital survey meter. The values ranged
from <0.01 to 3.66 μSv h-1.
The measured values were compared with the dose rates calculated using the activity
concentrations of 232Th, 226Ra and 40K in sand collected from each location and measured
in the laboratory using a HPGe detector. Calculated values ranged from 0.005 to 5.527 μSv
h-1. A good correlation was obtained between the calculated and the measured values.
However the calculated values were somewhat higher than the measured values. The
calculated annual effective dose ranged from 0.01 to 9.68 mSv with an average of 0.43
mSv. In 3% of the locations, the annual effective dose was greater than the worldwide
average annual effective dose of 2.4 mSv. The highest background radiation level was
recorded in ‘Nilwella’ (5°57'54.8"N 80°43'03.3"E) beach which is a newly identified location
with high radiation background.
This research is a part of an ongoing study to measure radiation levels along the entire
coastline of Sri Lanka.
