Development and intercomparison of a reusable radon-in-water standard

Radium-free standards are not readily available for proficiency testing of laboratories that conduct radon (²²²Rn) analyses of water. For this study, 33 identical, reusable, radon-in-water standards were prepared using a ²²⁶Ra-loaded filter sandwiched in polyethylene sheeting. The ²²²Rn concentrations in the ²²⁶Ra-free standards were measured by liquid scintillation counting and compared to 10 reference solutions containing ²²⁶Ra. The ²²²Rn concentrations measured in the standards were consistent (standard deviation of <2%), but averaged substantially less than concentrations determined in the ²²⁶Ra reference standards. At full ingrowth, 86% of the ²²²Rn produced by the sandwiched ²²⁶Ra sources emanated into the water. An intercomparison of radon-in-water standards, performed to examine the accuracy of analyses by commercial, government, and private companies, showed that 18 of the 21 participants reported concentrations within 25% of the known (693 Bq l^?1).     

Airborne gamma-ray emitters from Fukushima detected in New York State

An air-sampling network that operates continuously as part of New York State’s environmental surveillance program collected radionuclides emitted as a result of the Fukushima nuclear accident. Samples were collected, typically for 7 days each, by drawing ~600 m³ of air through a particulate-collecting filter followed in series by a canister containing activated charcoal. Additional air sampling was implemented at ~3-day intervals at two locations. Gamma-ray spectroscopy was used to confirm the detection of ¹³¹I, ¹³⁷Cs, ¹³⁴Cs, and ⁷Be in the particulate phase at all sites, with maximum concentrations near 1,260, 160, 160, and 5,200 μBq/m³, respectively. Gas-phase ¹³¹I, collected on activated charcoal, exhibited a maximum concentration of 3,400 μBq/m³ at the sites. Assessment of radionuclide levels in the air samples suggests that there were minimal health impacts from the airborne radionuclides as the activities contributed an insignificant amount to the annual human dose.     

Homogenization of food samples for gamma spectrometry using tetramethylammonium hydroxide and enzymatic digestion

Journal of Radioanalytical and Nuclear Chemistry - We have developed a method of food sample preparation for gamma spectrometry involving the use of tetramethylammonium hydroxide (TMAH) and/or...     

Assessment of gamma-ray emissions from natural and manmade decorative stones

Decorative stones (32 natural and 18 manufactured) and five ceramic tiles that are used in home interiors were measured with gamma-ray spectrometry, to identify and quantify the naturally occurring radionuclides. Activity concentrations of the radioisotopes varied by more than two orders of magnitude across the stone samples, with maximal levels of 3380, 850, and 2130 Bq/kg, for ²³⁸U, ²³²Th, and ⁴⁰K, respectively. A radiation index and measurements with a radiation meter established that the annual effective dose rates due to a 1 h/day exposure to gamma rays emitted by the granite samples were often low, but can occur as high as 1 mSv/year.