Self-absorption correction factor applied to 129I measurement by direct gamma–X spectrometry for Fucus serratus samples

The Potential Of I-129 as an Environmental Tracer

“…It is used for monitoring of environmental samples collected in vicinity of NFRP such as thyroid, urine, seaweed, and for nuclear waste by using high purity Ge or plenary Si detector (Suarez et al, 1996;Bouisset et al, 1999;Frechou et al, 2001;Lefevre et al, 2003;Frechou & Calmet, 2003;Barker et al, 2005). To lower the detection limits normally big samples (50−500 g) are used, which induces considerable attenuation at low energies.…”

“…Therefor the mass energyattenuation coefficient (self-absorption correction) at a given energy must be measured for all sample matrices with respect to that of the standard source. Experimentally obtained selfabsorption correction factors are used to obtain accurate results (Bouisset et al, 1999;Lefevre et al, 2003, Barker et al, 2005. To quantify self-absorption correction factors 210 Pb (46.5 keV) and 241 Am (59.6 keV), with gamma lines close to 129 I are used.…”

129I determination by direct gamma-X spectrometry and its application to concentration variations in two seaweed species

“…• standard gamma spectrometry to quantify radionuclides in samples using N-type HPGe detectors with a relative efficiency above 50% [10], and • transmission in relation to the energy of a parallel flux of photons (collimator) with a planar detector in view of determining mass attenuation coefficients [1][2]. The gamma spectrometers were calibrated using Analytics or Cerca multi-elementary sources (water equivalent resin matrix, density = 1.15 g.cm -3 ).…”

“…An attenuation correction factor at low energy was calculated using the mass attenuation coefficient of each seaweed species [1][2]. The coefficients for gamma-X rays of 129 I for Fucus serratus and Laminaria digitata are represented in table 2 and 3 respectively.…”

“…These corrections must not only take into account the density but also the elementary composition of the matrix seeing that the photoelectrical process becomes the dominating interaction phenomenon under 100 keV. We recently developed a corrective method based on transmission measurements [1][2] to determine these self-attenuation correction factors in relation to standard calibration sources. Temporal variations in the self-attenuation coefficient are related to variations in the elementary composition of the matrix, including variations in iodine in the case of seaweed.…”