Destructive and Nondestructive Determination of <sup>226</sup>Ra and <sup>228</sup>Ra in Drinking Water by Gamma Spectrometry

Abstract

The Safe Drinking Water Act (SDWA) mandates that the drinking water should be monitored for 226 Ra and 228 Ra isotopes and establishes the Maximum Contaminant Level of 185 mBq/L (5 pCi•L −1) for the sum. In addition, SDWA regulates the Detection Limit (DL) of 37.0 mBq/L (1 pCi/L) for each isotope. The purpose of this work is to develop a working method for the determination of radium isotopes in drinking water satisfying the regulatory requirements of U.S. Environmental Protection Agency by utilizing our extensive experience in low-background gamma spectrometry at this laboratory. Two versions of the method were studied: destructive and non-destructive. Destructive method used the BaSO 4 coprecipitation as well as 133 Ba tracer for chemical recovery. We have used three gamma spectrometers: low-background 102% and 134% efficient with top muon guards, as well as an ultralow-background 140% efficient with full muon guard. We obtained a range of DLs from 5.3 to 22.6 mBq/L for 226 Ra and from 7.4 to 30.4 mBq/L for 228 Ra using the destructive method. For non-destructive method, the DL range was 26.0 to 26.9 mBq/L for 226 Ra and 27.6 to 28.6 mBq/L for 228 Ra using the 140% detector. To verify the methods, 7 to 10 laboratory control samples were spiked with both 226 Ra and 228 Ra at two different activities of 37.0 and 185 mBq/L. The results were evaluated by performing a combined location/variance chi-square test at a right-tail significance of 0.01 (99% Confidence Level), as stipulated by EPA. The verification results passed the chi-square tests at both activity levels. The destructive method can be accomplished using low-background gamma spectrometry, whereas non-destructive method requires ultralow-background gamma spectrometry.

Influence of culture on strategic leadership in international developent projects

“…Eksterni faktori su povezani sa unutrašnjim faktorima na osnovu njihovog uticaja. Istraživanje koje je korišćeno za razvoj modela je i Khanovo i Spangovo predstavljanje KFU-a u MR projektima [18]. Takođe, ko-rišćen je i Colemanov [19] zaključak da strateški lideri moraju biti u stanju da uravnoteže agilnost i doslednostm što je od značaja za organizacije koje imaju visoke hijerarhijske strukture, složene administrativne procese i procedure, rade na udaljenim geografskim lokacijama i imaju timove koje karakteriše kulturna raznolikost.…”

Uranium Series Disequilibrium and Precision Measurement of Radionuclides Activity in Sediment Sample Using Low Background Gamma Spectrometry

“…The development of low-background gamma-ray spectrometer (LBGS) was originally for basic physics research such as neutrino oscillation, 0νββ decay, and dark matter search (Heusser, 1995;Povinec et al, 2004;Laubenstein et al, 2004;Aalseth et al, 2012;Armengaud et al, 2013;Khan et al, 2014) during the last two decades, however, LGBS has found several important applications such as monitoring natural radionuclides such as 226 Ra, 228 Ra (Semkow et al, 2019;Khan et al, 2020) as well as anthropogenic radionuclides such as fission products in the environment for contamination control and nonproliferation applications. The Nuclear Chemistry Laboratory (NCL) at the New York State Department of Health has been operating LBGS for over two decades (Semkow et al, 2002;Haines et al, 2011;Khan et al, 2014).…”