Using an ultrapure ⁴He spike in tritium measurements of environmental water samples by the ³He‐ingrowth method

Abstract

Dear Editor,Using an ultrapure 4 He spike in tritium measurements of environmental water samples by the 3 He-ingrowth method The tritium ( 3 H or T, half-life 12.32 years 1 ) concentrations of environmental water samples have already decreased below the level that can be accurately measured by conventional liquid scintillation or proportional counting techniques, even if electrolytic enrichment is used prior to the measurements. [2][3][4] In addition, when the precipitation infiltrates under the soil or ocean surface, the tritium concentration starts to decrease due to radioactive decay. Therefore, tritium concentrations of less than 0.5-1 TU (1 TU corresponds to a 3 H/ 1 H ratio of 10 À18 ) can hardly be measured by counting.He spike aliquots were admitted into the mass spectrometer (note that the uncertainty of the parameters of the exponential function is better than the last digits). The different components of the measured 4 He, i.e. 4 He blank and 4 He spike , have to be determined: the 4 He spike is calculated from the exponential curve, while the blank can be obtained as the difference between 4 He meas and 4 He spike . Figure 6. The results and the IAEA reference values of the TRIC-2008 tritium samples with 1s uncertainties.

Cesium, iodine and tritium in NW Pacific waters – a comparison of the Fukushima impact with global fallout

“…Tritium was then precisely analyzed in seawater samples using the 3 He in-growth method (Palcsu et al, 2010).…”

Differences in temporal changes of selected water quality parameters on Jasovská Planina Plateau (Slovak Karst, Slovakia)

“…The first samples for groundwater age estimation based on the tritium ( 3 H) content of water were also collected from the end of December 2013. Water samples for tritium have been analyzed using the 3He-ingrowth method (Palcsu et al 2010). Due to the principle of the method, the samples had to be stored for a couple of months so that 3 He is produced from the tritium decay.…”

Experimental investigation and modelling of tritium washout by precipitation in the area of the nuclear power plant of Paks, Hungary

“…All samples were then measured via LSC, with some also subjected to 3 He ingrowth method because this method is suitable for the measurement of very low tritium concentrations (Palcsu et al, 2010). As can be seen from Table 2, sample values obtained using the 3 He ingrowth technique correspond well with their LSC counterparts and as a result it can be stated that the low values produced with the latter method are valid, despite the large uncertainty and high detection limit.…”

“…As a result, helium partial pressures achieved in the mass spectrometer were comparable to ones those are measured during calibration, using well known air aliquots. The overall precision of the tritium measurements was better than 2.4% above 0.1 Bq l À1 (Palcsu et al, 2010).…”

“…The tritium concentration of collected rainwater was measured using the lowlevel liquid scintillation counting (LSC) technique (Kern et al, 2009), with some samples analysed via the lengthier yet more precise 3 He ingrowth method where greater accuracy was required (Palcsu et al, 2002(Palcsu et al, , 2010. Before taking LSC measurements, samples were distilled to minimize quenching (Svetlik and Budska, 2001).…”