Radiological Investigation of High Background Radiation Areas

Abstract

In this paper, we used the Hyper-Pure Germanium (HPGe) detector to measure 30 samples which are collected from north of Nile Delta near Rosetta beach in Egypt. The activity of primordial radionuclides, such as 238U, 235U, 232Th, and 40K was estimated. Concentrations ranged between 36.5–177.4, 50–397.5 and 56.1–168.9 Bq.kg−1 for 238U, 232Th and 40K respectively. Activity concentration of 235U and the variation in uranium isotopic ratio 235U/238U was calculated. External hazard indices (Hex) (or radium equivalent activity Raeq), activity concentration indices (I), alpha index (Iα), absorbed outdoor gamma dose rate (Dout), effective outdoor gamma dose rate (Eout) and Excess Lifetime Cancer Risk (ELCR) due to different samples are estimated. External hazard indices (Hex) are ranged between 0.32–2.04, radium equivalent activity (Raeq) are ranged between 118.67–753.91, the activity concentration indices (I) are 0.42–2.61, and alpha index (Iα) are 0.18–0.89. External hazard indices (Hex) in some samples more than unity then it exceeds the upper limit of exposure. Also, the radium equivalent activities (Raeq) are higher than the exemption limits (370 Bq.kg−1).

Distribution of gamma radiation dose rate related with natural radionuclides in all of Vietnam and radiological risk assessment of the built-up environment

“…The gamma radiation emitted by natural sources present in the earth's crust, in building materials, air, water, food and the human body is largely due to primordial radionuclides, mainly 40 K, 238 U and 232 Th series elements and their decay products. These primordial radionuclides have contributions of 35% for 40 K, 25% for 238 U and 40% for 232 Th to the absorbed dose rate in air as gamma radiation 24 ; consequently, the dose distribution depends on their activity concentrations 25 . Figure 7 presents a geographical map for Vietnam.…”

“…The conversion coefficient from absorbed dose rate in air to effective dose 6 , 18 (0.7 Sv G year −1 ) for an adult, and the outdoor (0.2) and indoor (0.8) occupancy factors 21 were used for estimating the annual outdoor (OAED) and indoor (IAED) annual effective doses based on the absorbed dose rate in air ( D air ) measured from the car-borne survey; OAED and IAED (mSv year −1 ) were calculated using Eqs. ( 2 ) and ( 3 ) 25 . …”

“…The external hazard index due to gamma radiation was calculated using Eq. ( 6 ) 9 , 25 : where A U , A Th and A K are the concentrations in Bq kg −1 of 238 U, 232 Th and 40 K, respectively. When the external hazard index values did not exceed the acceptable limit which is less than unity (H ex < 1), radiation hazards could be assumed to be negligible in the study area.…”

Determination of Activity Concentration of Natural Radionuclides and Radiation Hazards’ Assessment of Building Materials in High Background Radiation Areas of Homa and Ruri, Kenya

“…The results obtained in this work have been compared with results reported in building materials in other high background radiation areas in Kenya and others around the world as tabulated in Table 5 [ 8 , 11 , 20 , 21 ]. 40 K was 70% and 50% higher in Homa and Ruri, respectively, compared to Mrima hill, Kenya.…”

Comprehensive exposure assessments from the viewpoint of health in a unique high natural background radiation area, Mamuju, Indonesia

“…Calculation of external exposure dose assumed that the population received external exposure for 8 h outside the home (from 8 am to 4 pm), considering that almost all residents who lived in the HNBRA are farmers with a total of 7000 h for radon occupancy factor in houses 34 , 60 . For ingestion, the daily consumption of water was 1.6 L d −1 based on the questionnaire survey, and the dose conversion factors for adults are reported as 2.8 × 10 –7 Sv Bq −1 for 226 Ra, 4.5 × 10 –8 Sv Bq −1 for 238 U and 2.3 × 10 –7 Sv Bq −1 for 232 Th 61 .…”