Authors:R. Acharya, A. Nair, K. Sudarshan, A. Goswami, and A. Reddy
A summary of k0-based R&D work on neutron activation analysis (NAA), internal mono standard NAA (IM-NAA) and prompt gamma-ray NAA (PGNAA)
is presented. The k0-based NAA was standardized by characterizing irradiation sites of research reactors, validated using reference materials
and applied to samples of different origin. Recently IM-NAA method was developed, validated for small and large size samples
and applied for the analysis of large size as well as non-standard geometry samples. Studies on PGNAA included characterization
of neutron beam, determinations of detection efficiency and prompt k0-factors, and analytical applications.
Authors:Rupali Lagad, D. Alamelu, R. Acharya, and Suresh Aggarwal
Instrumental neutron activation analysis (INAA) was employed to determine concentrations of 19 elements (As, Ba, Br, Ce, Co,
Cr, Cs, Fe, K, La, Mn, Na, Nd, Rb, Sc, Sm, Th, Yb and Zn) in a large number (55) of tea samples (from market as well as virgin
tea leaves) from different locations in India (Assam, Darjeeling, Munnar and Kangra). The results obtained in the present
work are compared with those reported in literature. The concentration levels, their variations with collection locations
and the correlations among different elements in these samples are discussed.
Authors:R. Acharya, P. Burte, A. Nair, A. Reddy, and S. Manohar
Multielement analysis was carried out in two samples of natural rubies obtained from Kenya and Tanzania and a synthetic ruby obtained locally. The trace element profile was used to characterise the ruby samples. Instrumental Neutron Activation Analysis (INAA) by the single comparator (K0 method) was used to determine the concentrations of 22 elements with gold as the comparator. High resolution -ray spectrometry was employed for radiometric assay of the activation products. The accuracy and precision were evaluated by analysing standard reference materials such as USGS-W-1 and AGV-1 and were found to be satisfactory.
Authors:R. Sathyapriya, Suma Nair, V. Kamesh, R. Prabhath, Madhu Nair, R. Acharya, and D. Rao
A study was conducted to estimate the thorium concentration in locally grown vegetables in high background radiation area
(HBRA) of southern coastal regions of India. Locally grown vegetables were collected from HBRA of southern coastal regions
of India. Thorium concentration was quantified using instrumental neutron activation analysis. The samples were irradiated
at CIRUS reactor and counted using a 40% relative efficiency HPGe detector coupled to MCA. The annual intake of thorium was
evaluated using the consumption data provided by National Nutrition Monitoring Board. The daily intake of 232Th from the four food categories (green leafy vegetables, others vegetables, roots and tubers, and fruits) ranged between
0.27 and 5.352 mBq d−1. The annual internal dose due to ingestion of thorium from these food categories was 46.8 × 10−8 for female and 58.6 × 10−8 Sv y−1 for male.
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:N. Sharma, R. Prakash, A. Srivastava, U. Sadana, R. Acharya, N. Prakash, and A. Reddy
In the Nawanshahr–Hoshiarpur region of Punjab, India, more than 1000 hectares of agricultural land is significantly affected
by high levels of selenium (Se). Studies were carried out to examine Se levels in soil and crops such as wheat grains, wheat
husk, rice, maize and mustard using neutron activation analysis. The Se concentrations in soil and crop products were found
to be ranging from 2.7 to 6.5 mg kg−1 and 13 to 670 mg kg−1, respectively, indicating significantly high selenium in these crop products. Two reference materials were analysed for Se
contents by INAA as controls.
Authors:R. Dutta, R. Acharya, V. Chakravortty, A. Nair, A. Reddy, S. Chintalapudi, and S. Manohar
Three ferromanganese crusts from different locations of the Indian Ocean were analysed by neutron activation analysis using
thek0 method (k0 NAA method) for studying the distribution of some trace elements along with Fe and Mn. Another crust from the Lau basin of
the Pacific Ocean was investigated for comparison of the influence of different oceanic conditions on the trace element distributions
in ferromanganese crusts. Variation in Co concentration along with the Mn/Fe ratio were discussed in terms of the hydrogenous/hydrothermal
nature of the crusts. The normalised REE content was used to identify possible anomalies. The observed Ce anomaly is discussed
in the light of the depositional environment. The precision and accuracy of the method were confirmed by measuring the elemental
concentrations in a USGS nodule standard NOD A-1.
Authors:R. Acharya, K. Swain, Amit Kumar, Nicy Ajith, R. Verma, and A. Reddy
For standardization of k0-based instrumental neutron activation analysis, k0-factors for short-lived nuclides (half-lives—11 s to 37 min) of elements F, Se, Sc, Al, V, Ti, Cu, Ca, Mg, I, and Cl with
respect to gold (197Au) were determined using pneumatic carrier facility (PCF) at CIRUS reactor of BARC, Mumbai. Characterization of PCF was carried
out by cadmium-ratio method using Au and Zr. The experimental k0-factors of the isotopes were found to be in good agreement with the recommended k0-factors in most of the cases, as evident from the values of % error and U-score at 95% confidence level. The method was validated
by determining concentrations of elements through their short-lived nuclides in one type of the synthetic multielement standards
(SMELS-I) obtained from SCK-CEN, Belgium. The method was also applied for determination of concentrations of some of the elements
in two reference materials of IAEA, SL-3, and SL-1.
Authors:D. Mishra, R. Acharya, K. Swain, R. Joshi, V. Joshi, P. Verma, A. Hegde, and A. Reddy
Thorium along with its daughter products present in the soil is one of the major contributors to the external gamma dose in
the environment. To establish the dose levels, quantification of thorium contents in soil samples is very important. As a
part of pre-operational environmental radiological surveillance, a total of 23 soil and six sand samples were collected from
different locations around the proposed nuclear power plant site of Jaitapur, Maharashtra. Thorium concentrations in these
samples were determined by instrumental neutron activation analysis (INAA). Samples were irradiated with neutrons in Apsara
reactor at a neutron flux of ~5 × 1011 cm−2 s−1 and radioactive assay was carried out using high resolution gamma ray spectrometry. Relative method of INAA was used for
quantification of thorium utilizing 311.9 keV gamma ray of 233Pa, the daughter product of 233Th. The concentrations of thorium in the soil and sand samples were in the ranges of 4.0–18.8 and 1.2–6.2 mg kg−1 respectively.
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.