Polymer Engineering and Science

The purpose of this work is to estimate dose received in case of release of radionuclide into the atmosphere from the under-construction Rooppur Nuclear power plant (NPP) due to a hypothetical accident with the help of an atmospheric dispersion model. A generic source term code has also been developed using MATLAB by following NUREG-1228. The sensitivity analysis is based on variation of the received total effective dose equivalent (TEDE) corresponding to the variation of the uncertain input parameters. The sensitivity was seen to be higher at stable conditions with the change of high wind speed. Estimated TEDE dose results for Xe-133 at different downwind distances from Rooppur NPP site in different atmospheric stability classes. The maximum TEDE of 6.40E-06 Sv was estimated at maximum distance of 0.7 km from the site for stability class A, whereas, in case of unstable stability class B, it was 5.70E-05.

This paper focuses on the relationship between radon concentration and lung cancer morbidity from the methodological point of view. Geographically aggregated data on cancer risk factors, collected for 3142 US counties and county-equivalents are discussed. Apart from the Least-Squares and Bayesian linear regression analysis, for the first time the Maximum Entropy Method (MEM) is used to investigate this type of correlation, where major confounding factors under considerations are altitude and ultraviolet (type B) radiation. First two methods of analysis show statistically significant decrease in the group with the high smoking prevalence. This trend did not depend on the sex of the subjects or their prevalence of smoking. The use of MEM provides a much richer picture of a clear trend of decreasing morbidity of lung cancer with increasing radon concentration level. Last but not least, it is shown that the data binning has to be made carefully as otherwise the conclusions based on the data can be dubious.

The aim in this present work is to determine the specific activities of 226Ra, 232Th and 40K in rock samples collected from Mounana in Gabon, to assess the contribution of natural radioactivity. A p-type high-purity germanium detector has been coupled with a multichannel analyser DSA-1000 to perform measurements and data processing. The energy resolution of the 1332 keV60Co line is still found to be 1.8 keV at FWHM, with a relative efficiency of 30%. The specific activities average values of 226Ra, 232Th and 40K are 6554±198 Bq/kg, 63±12 Bq/kg and 513±93 Bq/kg, respectively wet weight. To assess the radiological risks due to 226Ra, 232Th and 40K, many parameters were estimated. The average value of annual effective dose was 18.95 mSv from the studied area. Rock from Mounana presents a high radioactivity, and we are planning to measure radon in homes to assess the risks of living in Mounana.

Twenty borehole (BH) and 15 hand-dug wells (HD) water samples were collected from Ifako-Ijaiye for this study. The samples were analysed using NaI (TI) detector for radioactivity and BUCK200 AAS for elemental concentrations. The Effective Dose Rates (EDR) and Excess Lifetime Cancer Risks (ELCR) were calculated from activity concentrations of 40K, 238U and 232Th. The activity and elemental concentrations were statistically correlated. The mean activity concentrations of 40K, 238U and 232Th in the BH water were 8.77±8.40 Bq/L, 1.03±0.19 Bq/L and 0.93±0.15 Bq/L, respectively; and 10.12±0.07 Bq/L, 0.94±0.34 Bq/L and 0.89±0.10 Bq/L, respectively in the HD water. The EDR and ELCR in the study were higher in the infant than either creche or adult. The elemental concentrations in BH water were higher than the World Health Organisation (WHO) recommended limits. The ELCR in the study is higher than the USEPA limit; therefore, drinking untreated water from the area should be discouraged.

The present study aims to assess 222Rn concentration and its radiological hazard for agricultural soil samples collected from Wadi Al-Hussini and Tuban as agricultural areas. Forty agricultural soil samples were collected from Lahj Governorate, Yemen. AlphaGUARD was used to measure radon concentration, and radon exhalation rates and annual effective dose in the agricultural soil samples were calculated. The average 222Rn activity concentration, area radon exhalation rate, mass radon exhalation rate and annual effective dose outdoor are as follows: 5170 ± 1740 Bq m−3, (12.4 ± 4.18)×10−4 Bq m−2s−1, (20.3 ± 6.82)×10−6 Bq kg−1s−1 and 49.13 mSv y−1 for Wadi Al-Hussini, 7263±2061 Bq m−3, (17.4±4.95) × 10−4 Bq m−2s−1, (28.5±8.08)×10−6 Bq kg−1s−1 and 69.03 mSv y−1 for Wadi Tuban. The average value of 222Rn concentration in agricultural soil gas in Wadi Al-Hussini and Tuban is much higher than the value of United Nations Environment Programme (UNEP), which the recommended reference 100 Bq m−3.

The linear non-threshold (LNT) single-hit (SH) dose response model for cancer risk assessment is assessed with respect to its historical foundations. This paper examines and summarises how mistakes, ideological biases, and scientific misconduct by key scientists affected the acceptance, validity, and application of the LNT single-hit model for cancer risk assessment. This analysis concludes that the LNT single-hit model was inappropriately adopted for governmental risk assessment, regulatory policy and practices, and for risk communication.