Measurement of natural radioactivity of building materials used in the southern valley region of Manipur, India

Abstract

A study of natural radionuclides of different types of houses was conducted at 493 houses in the southern valley region of Manipur, India. The average annual effective doses of gamma radiation level in indoor and outdoor were estimated from the measurements using Micro R-survey meter and found as 1.25 ± 0.10 (range: 1.02–1.38) mSv/y and 0.76 ± 0.08 (range: 0.58–0.99) mSv/y for reinforced cement concrete (RCC) houses, followed by 1.07 ± 0.09 (range: 0.95–1.19) mSv/y and 0.76 ± 0.08 (range: 0.67–0.95) mSv/y for Adobe laid earthen houses, 1.05 ± 0.09 (range: 0.78–1.24) mSv/y and 0.74 ± 0.08 (range: 0.58–0.91) mSv/y for Assam-type (AT) brick houses, 0.83 ± 0.09 (range: 0.40–1.07) mSv/y and 0.72 ± 0.08 (range: 0.23–0.97) mSv/y for AT mud houses and 0.73 ± 0.08 (range: 0.66–0.82) mSv/y and 0.74 ± 0.07 (range: 0.64–0.82) mSv/y for AT katcha houses. The activity concentration226Ra,232Th, and40K of building materials was evaluated using the gamma ray spectrometry and found average value as 42.4 (range: 23.0–69.9) Bq/kg, 111.3 (range: 23.8–214.5) Bq/kg, and 1369.0 (range: 995.7–2284.6) Bq/kg. Moreover, the annual effective dose conceived from the building material was found as 1.1 mSv/y from Portland cement, 1.4 mSv/y from sand, and 1.5 mSv/y from brick. Seasonal variations of indoor effective dose rates were observed in RCC houses; the highest dose rate was observed during the premonsoon season followed by postmonsoon and least with monsoon season.