A total reflection X-ray fluorescence method for the determination of chlorine at trace levels in nuclear materials without sample dissolution Sangita Dhara, a Nand Lal Misra, a * Uday Kumar Thakur, b Dipti Shah, b R. M. Sawant, b K. L. Ramakumar b and Suresh K. Aggarwal a A total reflection X-ray fluorescence (TXRF) method for the determination of chlorine at trace levels in nuclear fuel samples is described. Chlorine present in trace concentrations in nuclear fuel materials such as U 3 O 8 , (U,Pu)C, PuO 2 and Pu-alloys was first separated from the solid matrix by pyrohydrolysis as HCl and was collected in 5 mM NaOH solution. This solution was analyzed for chlorine by TXRF spectrometry using Cl Ka analytical line excited by W La. Cobalt was used as internal standard. The precision for such chlorine determination was found to be within 27% (n = 4) when the analysis was carried out in air atmosphere. This could be improved to 8% by making TXRF measurement in flowing helium atmosphere. The results obtained from TXRF determinations were also compared with those obtained from ion chromatography (IC) and were in good agreement. The collection of distillate during pyrohydrolysis in NaOH helped in counterchecking loss of chlorine during TXRF sample preparation. The average deviation of TXRF-determined values in helium-purged TXRF measurements with IC determined values (as chloride) was 15% at a chlorine concentration level in the range of 1–70 mg/mL. Copyright © 2012 John Wiley & Sons, Ltd. Keywords: TXRF; Pyrohydrolysis; Nuclear Materials; Ion Chromatography; Chlorine Introduction Quality assurance control of the nuclear materials such as nuclear fuels, structural materials, cladding, and so on, for the presence of trace elements is an important step from the point of view of sustainable, efficient and safe operation of nuclear reactors. [1–3] Presence of both metallic and non-metallic impurities at trace and ultra trace levels can affect the performance of the fuel and cause detrimental effects on the structural materials. Hence, the amounts of these trace impurities, which can be tolerated in nuclear materials, is very specific and have to be determined using suitable analytical techniques depending upon the nature of sample, sensitivity, precision and accuracy required. Although several trace element determination techniques are available to determine metals, only a few techniques are available for determi- nation of non-metals. The non-metallic impurities include H, B, C, O, F, P, S and Cl. Among these trace nonmetallic impurities; chlorine is one of the very important elements to be determined because of its extremely corrosive nature. Even at very low concentrations, it can lead to depassivation of the oxide film on the surface of the clad, thereby leading to corrosion of the cladding material [4] and separation of phases. Similar effects are observed if chlorine is present in higher amounts in nuclear fuel. Chlorine as an impurity becomes incorporated into the nuclear materials during the various stages of their fabrication and processing. Because of these reasons, the specification limits for chlorine in nuclear materials are very stringent. In UO 2 and MOX fuel, the specification limit for chlorine is 15 ppm in (U, Pu)C and in (U,Pu)O 2 it is 50 ppm (Cl + F) whereas in ThO 2 , Zircaloy-2 and Zr-2.5% Nb alloys, this value is fixed at 25 ppm, 20 ppm and 4–5 ppm, respectively. [3] Ion chromatography (IC), spectrophotometry and ion selective electrode are some of the widely used techniques [5,6] for chlorine determination. Methods such as mass spectrometry, differential pulse cathodic stripping voltammetry, neutron activation analysis, x-ray fluorescence (XRF) and glow discharge mass spectrometry (GDMS) can also be used. [6–9] Total reflection x-ray fluorescence (TXRF), a variant of energy dispersive x-ray fluorescence (EDXRF), is a promising technique for trace and ultra trace determinations of both metallic and non-metallic impurities in different matrices. Compared with most of the well-established trace element determination techniques, TXRF is simple, fast, and accurate, requires much less sample amount (10–50 mL) and needs addition of only a single internal standard for quantification. In contrast to normal XRF, this technique does not suffer from matrix effects; hence, does not require matrix matched standards. It has detection limits several orders better compared with conventional XRF. [10,11] Requirement of much less sample amount and generation of less analytical waste makes it very attractive for the analysis of radioactive samples. [12] However, TXRF has a disadvantage of requirement of samples in the form of solutions in most cases and thus requiring dissolution of solid samples. The sample dissolution, especially for nuclear materials, is generally a cumbersome procedure and can lead to the possibility of addition of some impurities into the sample. * Correspondence to: Nand Lal Misra, Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India. E-mail: nlmisra@yahoo. com, nlmisra@barc.gov.in a Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India b Radio Analytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India X-Ray Spectrom. (2012) Copyright © 2012 John Wiley & Sons, Ltd. Research Article Received: 21 March 2012 Accepted: 19 April 2012 Published online in Wiley Online Library (wileyonlinelibrary.com) DOI 10.1002/xrs.2400