Uranium and thorium mixed oxides are being prepared using natural U and Th for studies on fuels for Advanced Heavy Water Reactors,
wherein composition of U and Th is specific and requires strict control in terms their contents and homogeneity. Chemical
quality control necessitates accurate and precise compositional characterization of the fuel material by a suitable analytical
method. Among various analytical methods for U and Th, instrumental neutron activation analysis (INAA) is one of the best
methods for their simultaneous determination without chemical dissolution and separation. INAA methods using reactor neutrons
namely thermal NAA and epithermal NAA were standardized for the determination of U and Th in their mixed oxides. Standards,
synthetic samples and U–Th mixed oxide samples, prepared in cellulose matrix, were irradiated at pneumatic carrier facility
of Dhruva reactor as well as at self serve facility of CIRUS reactor under cadmium cover (0.5 mm). Radioactive assay was carried
out using a 40% relative efficiency HPGe detector. Both activation and daughter products of 238U (239U and 239Np) and 232Th (233Th and 233Pa) were used for their concentration determination. The method was validated by analyzing synthetic samples of 6–48%U–Th
mixed oxides. The standardized method was used for the concentration determination of U and Th in 4–30%U–Th mixed oxide samples.
Results of U and Th concentrations including associated uncertainties obtained from the INAA methods are presented in this
Authors:H. Sodaye, P. Pujari, A. Goswami, and S. Manohar
This paper discusses the diffusion of Cs+ and Zn2+ ions through Nafion-117 cation exchange membrane using radiotracer technique. The validity of the Donnan's equation is checked for these ions using65Zn and137Cs radiotracers. The paper also discusses the diffusion of Cl– and I– anions studied by using36Cl and131I radiotracers. The probable mechanism of diffusion of these anions in the presence of Zn2+ cations is suggested.
Authors:S. Chhillar, R. Acharya, R. Pai, S. Sodaye, S. Mukerjee, and P. Pujari
A particle induced gamma-ray emission method using proton beam in conjunction with in situ current normalization approach
was standardized for non-destructive determination of low Z element lithium and was applied for quantification of Li in lithium
doped neodymium dititanate (Nd2Ti2O7) ceramic sample. Thick pellets of heat treated samples, their precursors and Li standards were prepared separately by homogeneously
mixing with cellulose and fixed amount of F used for in situ current normalization. For validation of the method, four synthetic
samples were also analyzed. Samples and standards were irradiated with 4 MeV proton beam (~5 nA current) from folded tandem
ion accelerator (FOTIA) BARC, Mumbai. Characteristic γ-rays of 478 keV from 7Li to 197 keV from 19F were measured by high resolution γ-ray spectrometry. The Li concentrations determined in the six samples were in the range
of 0.29–0.85 wt%. The Li contents in heat treated samples gave the idea about loss of Li compared to their precursors.
Authors:S. Chhillar, R. Acharya, S. Sodaye, K. Sudarshan, S. Santra, R. Mishra, C. Kaushik, R. Choudhury, and P. Pujari
Barium borosilicate glass (BaBSG) is proposed as a potential candidate for vitrification of nuclear waste generated from thoria
based nuclear reactors. Along with fission products, activation products and many inactive chemicals, like fluorine in the
form of HF are expected to be present in the dissolver solution with nuclear waste. As vitrification occurs at high temperature,
it is important to quantify fluorine in BaBSG. Due to its complex matrix, most of the wet chemical and nuclear analytical
methods encounter problems in the estimation of fluorine. Particle induced γ-ray emission (PIGE) method has been standardized
for non-destructive determination of fluorine contents in BaBSG samples utilizing measurement of prompt gamma-rays from 19F (p, p’γ) 19F reaction. Experiments have been carried out with thick pellet targets prepared in cellulose matrix using 4 MeV proton beam
from the folded tandem ion accelerator at BARC, Mumbai. For obtaining current normalized count rate of interest, beam current
variation was monitored by the Rutherford backscattering spectrometry (RBS) method as well as by the in situ approach using
an externally added element sensitive to PIGE. In this paper standardization of PIGE methods for F determination, validation
of methods using synthetic samples, and application to BaBSG samples are reported.