Evaluating radiation risks and resource opportunities associated with phosphogypsum in the Philippines

Phosphogypsum (PG) accumulates during wet-phosphoric acid production for fertilizers. In the Philippines, PG is partly (40%) utilized to produce gypsum walls and cement. This work assesses the radiological risks and resource opportunities associated with PG stacks in the Philippines. The conducted in situ radiometric survey measured the activity concentrations of 40K, 238U, and 232Th at 270 locations. Besides, another 120 surface samples were collected. Pure PG exceeds the recommended radiation limits, but simple dilution with conventional materials can make PG available as an inexpensive secondary raw material for construction. PG further contains relevant concentrations of rare earths and Y (195 ppm).

In situ Ground Radiometric Survey and Risk Assessments of Allanite-Bearing Beach Sands in Erawan, Palawan

Past exploration for U deposit in the Philippines discovered the mineralization of radioactive allanite in Palawan. The allanite occurs as sand component in the heavily populated beach of Erawan, San Vicente, Palawan. This work assessed the risks associated with the radionuclides in Erawan beach by in situ ground radiometric survey of K, U, and Th in 694 sampling points. Principal component analysis (PCA) and Pearson correlation coefficient were used to determine the similarity between the radionuclides and to identify other probable anthropogenic sources of radionuclides. Our results show that the mean activity concentrations of K (597.8 Bq kg-1) and Th (93.15 Bq kg-1) are equivalent to 1.5 and 3.1 times of the world average natural radioactivity levels in soil, respectively, while the mean U (34.7 Bq kg-1) is similar to the world average. The mean radiological risk assessments like radium equivalent, gamma specific activity index, external hazard index, internal hazard index, absorbed gamma dose rate, annual effective dose equivalent, annual gonadal equivalent dose, and excess lifetime cancer risk are 213.96 Bq kg-1, 0.78, 0.58, 0.67, 97.24 nGy h-1, 119.25 µSv y-1, 684.39 µSv y-1, and 0.42 (10-3), respectively. Th consistently correlated most to the risks. We attribute the occurrence of Th to the presence of allanite, K to fertilizer use for farming, and U to both the allanite and farming. The results of our study can provide important baseline data for future detailed studies or monitoring of the long-term effects of elevated radiation levels to the local population of Erawan.

RADIOMETRIC SURVEY OF THE TYAA RIVER SAND MINE IN KITUI, KENYA

Gamma spectroscopic analyses of sand and rock samples from Tyaa River report an average activity concentration of 33 ± 1, 55 ± 2.8 and 812 ± 40.46 Bqkg−1 for 226Ra, 232Th and 40K, respectively in the sand. A similar analysis of rock samples reveals a mean of 21 ± 2.47, 49 ± 2.47 and 782 ± 39.13 Bqkg−1 for 226Ra, 232Th and 40K, respectively. The absorbed dose rate in rocks averaged 75 ± 3.78 nGyh−1, while in the sand was 86.2 ± 4.31 nGyh−1. The ranges and mean radiological hazard indices (radium equivalent, internal and external) were within the permissible limits and the use of sand and rocks from this mine as construction material pose no health risks. Correlation analysis between the radioactivity in the sand and rocks reveals weak non-linear positive relationships suggesting that they might be from different bedrocks.

Radiometric Evaluation of Radionuclides in Some Selected Mining Sites across Azara Development Area of Nasarawa State, Nigeria

The data for this research contains the in-situ measured activity concentration of radionuclides and gamma-radiation dose rate obtained from the radiometric survey in Azara development area of Awe Local Government, Nasarawa State, Nigeria. The data were manually collected in eight (8) locations with 20 data taken from each point using a portable hand held Thermo Scientific Interceptor and a radionuclide IdentiFINDER. The descriptive statistical analysis of the data was equally explored for possible statistical relationships. The result obtained is made available publicly for further extended analyses that can provide insights into the safety status of the study area from radiological health concerns. The data could also serve as a significant baseline radiometric data for future researches and monitoring initiative in Azara and its environs. The data for this research contains the in-situ measured activity concentration of radionuclides and gamma-radiation dose rate obtained from the radiometric survey in Azara development area of Awe Local Government, Nasarawa State, Nigeria. The data were manually collected in eight (8) locations with 20 data taken from each point using a portable hand held Thermo Scientific Interceptor and a radionuclide IdentiFINDER. The descriptive statistical analysis of the data was equally explored for possible statistical relationships. The result obtained is made available publicly for further extended analyses that can provide insights into the safety status of the study area from radiological health concerns. The data could also serve as a significant baseline radiometric data for future researches and monitoring initiative in Azara and its environs.