Environmental Liquid Scintillation Analysis

TLDR: In this article, the principles of ultralow-level liquid scintillation spectrometers are introduced and the sources of background signals and the means to reduce background are discussed.

Abstract: Principles of ultralow-level liquid scintillation spectrometers are introduced in this chapter. The sources of background signals and the means to reduce background are discussed. Electronic pulse discrimination and anticoincidence counting allow the determination of low radioactivities and the separation of α- and β-events into their respective spectra. These features make liquid scintillation counting (LSC) methods practical for simultaneous detection of low α and β activities in environmental samples, which are described. LSC methods are presented and discussed for 3 H, 14 C, 63 Ni, 89 Sr, 90 Sr/ 90 Y, and 99 Tc, transuranium elements including plutonium and for most important natural radionuclides, 222 Rn, Ra, U and Th isotopes, and 210 Pb and 210 Po. Because the radiation exposure from environmental radioactivity arises largely from natural radionuclides, the importance of their analyses is discussed along with the sensitive methods used for their analysis. A section is devoted to radiometric methods to differentiate between biogenic and fossil 14 C in fuels. Spectrum unfolding or deconvolution of low-activity α-spectra is discussed.