222Rn and 226Ra Concentrations in Spring Water and Their Dose Assessment Due to Ingestion Intake

Temporal variation of tritium concentration in monthly precipitation collected at a Difficult-to-Return Zone in Namie Town, Fukushima Prefecture, Japan

This article discusses tritium concentrations in monthly precipitation in part of the Difficult-to-Return Zone in Namie Town during 2012-2021. The tritium concentrations, which were measured with a low background liquid scintillation counter after carrying out an enrichment procedure, fluctuated seasonally from 0.10 ± 0.02 to 0.85 ± 0.02 Bq L-1. This range of concentrations is concluded to not be unusual based on comparisons with the concentrations at other sites and estimates of the past range of the concentrations. Moreover, no significant variations in observed tritium concentrations were observed due to decommissioning work at the Fukushima Dai-ichi Nuclear Power Plant. These results contribute to understanding the background level of tritium concentration in precipitation before the oceanic discharge of treated water from the Fukushima plant. In addition, this article evaluates the amount of tritium supplied to the ocean by terrestrial rainwater pouring into the Pacific Ocean via Ukedo River, which flows through Namie Town; this information will contribute to the discussion on the impact of the oceanic discharge of treated water.

Calibration experiments for radon in drinking water measurements using portable-type electrostatic-collection radon monitors

Portable-type electrostatic-collection radon monitors (RAD7) are often used for in-situ measurements of radon in water. In this study, we evaluated the calibration factors and their uncertainties for two RAD7 monitors based on comparative measurements with the liquid scintillation counting method. In the first experiment, we found that both RAD7 monitors had relatively large uncertainties due to leakage of radon gas that bubbled from the gaps between the lids of the desiccant container and the glass vial. Therefore, for the second experiment, these gaps were closed as much as possible using parafilm and clay, respectively. As a result, the relative uncertainties for both RAD7 monitors were significantly decreased. Furthermore, we collected spring water samples to confirm the reliability of radon concentrations. After closing the leakage point, the uncertainty of radon concentrations in spring water we measured using the typical protocol of the RAD7 were significantly lower, which improves the measurement.

Investigation of radioactivity level in drinking water resources and soil samples collected from the Hawraman villages, Iraq

In the present study, the RAD7 and NaI(Tl) techniques were utilized to determine the radon concentrations in drinking water resources and the natural primordial radionuclides in soil samples collected from Hawraman villages. The measured radon concentrations ranged from 1.7 ± 0.6 to 34.0 ± 2.8 Bq L^-1 with an arithmetic mean of 14.8 ± 1.2 Bq L^-1. This research demonstrates that roughly 54% of drinking water samples exceed the EPA-recommended level of 11.1 Bq L^-1. For adults, children, and infants, the total annual effective doses for the three types (D_ing, D_inh, and D_di) vary from 7.6 to 149.2 μSv y^-1 with an average of 65.0 μSv y^-1, 8.1-160.0 μSv y^-1 with an average of 69.7 μSv y^-1, and 10.5-207.0 μSv y^-1 with an average of 90.2 μSv y^-1.18.2%, 22.7%, and 36.4%, respectively, of the annual effective dose for adults, children, and infants exceeds the 100 μSv y^-1 level recommended by WHO and UNCEAR 2000. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴ K in soil samples varied from 10.9 ± 0.1 to 32.6 ± 0.2 Bq kg^-1, 18.3 ± 0.4 to 52.1 ± 0.6 Bq kg^-1, and 252.7 ± 2.5 to 585.6 ± 3.7 Bq kg^-1. The arithmetic mean concentrations of ²²⁶Ra, ²³²Th, and ⁴ K were determined to be 19.4 ± 0.2 Bq kg^-1, 36.2 ± 0.5 Bq kg^-1and 426.6 ± 3.2 Bq kg^-1, respectively. This research reveals that the average soil activity concentrations of ²²⁶Ra, ²³²Th, and ⁴ K are within the global average limits of 32, 45, and 420 Bq kg^-1, respectively. Comparing the concentrations to global averages, some soil samples revealed significant amounts of radionuclides, with around 18% of ²³²Th and 41% of ⁴ K. The computed radiological hazard indices of 100% of Ra_eq., 82% of D_out, 82% of E_out, and 95.5% of ELCR_out are all below the internationally recommended levels declared by Unscear 2000.