S. Anilkumar

Studies on matrix interferences during uranium analysis by extractive liquid scintillation technique

The efficiency of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) in reducing the influence of salinity and extraction of iron and calcium into the organic phase along with uranium was studied. DTPA has been observed to be more suitable complexing agent compared to EDTA. Iron and calcium were found to be separated quantitatively with more than 95% recovery for uranium, facilitating its rapid and interference free analysis in the presence of DTPA. Uranium recovery under high salinity conditions was also observed to be in the range 89.7–98.6% in the presence of DTPA.

Application of spectrum shifting methodology to restore NaI(Tl)-recorded gamma spectra, shifted due to temperature variations in the environment.

A method has been standardized for restoring a shifted differential pulse height spectrum from a scintillator based gamma ray spectrometer recorded at measurement temperature, to the position of a desired spectrum, recorded at a reference temperature. The method is based on the assumption that the spectrum obtained at measurement temperature represents the same statistical distribution as that at reference temperature but with different energy scales. A computer program has been developed for calculation of the transformation between the energy scales and for the restoration of the shifted spectrum. The method developed has been successfully applied for the restoration of gamma spectra measured at different temperatures.

A comparative study of 232 Th and 238 U activity estimation in soil samples by gamma spectrometry and neutron activation analysis technique

Neutron activation analysis (NAA) is a well-established analytical technique. It has many advantages as compared to the other commonly used techniques. NAA can be performed in a variety of ways depending on the element, its activity level in the sample, interference from the sample matrix and other elements, etc., This technique is used to get high analytical sensitivity and low detection limits (ppm to ppb). The high sensitivity is due to the irradiation at high neutron flux available from the research reactors and the activity measurement is done using high resolution HPGe detectors. In this paper, the activity estimation of soil samples using neutron activation and direct gamma spectrometry methods are compared. Even though the weights of samples considered and samples preparation methods are different for these two methods, the estimated activity values are comparable.

Determination of 231Pa in Monazite and Other Streams of the Thorium Production Cycle

Monazite (chief source of thorium) which is available in plenty in the beach sands of Kerala, India, contains uranium in the range of 0.25% to 0.35%. An attempt has been made to estimate 231Pa in monazite and the corresponding process stream samples of the thorium production cycle. This paper reports the 231Pa activity in these samples, after coprecipitation of 231Pa on MnO2 carrier and estimation by γ-ray spectrometry. The estimation shows about 1000 Bq/kg of 231Pa in monazite. This is the first reported estimate of 231Pa in monazite.

Calibration and optimization of alpha-beta separation procedures for determination of radium/radon in single- and two-phase liquid scintillation systems

Liquid scintillation alpha beta discrimination technique based on pulse shape analysis (PSA) was evaluated for determination of 226Ra and 222Rn in water samples. In view of the significance of calibration, for the reliable and precise determination of 226Ra and 222Rn concentrations in water samples, calibration procedures were standardized for single and two phase systems using Quantulus 1220 liquid scintillation counter. PSA optimization and efficiency calibrations were performed using 226Ra standard rather than conventionally used pure alpha and beta standards and substantiated by measuring the activity concentrations of 226Ra and 222Rn in the spiked water samples.

Study of liquid scintillation alpha spectral properties

Alpha spectra were acquired with Quantulus 1220 liquid Scintillation Counter (LSC) and correlations among parameters, such as alpha particle energy, sample quenching, peaks centroid and resolution were established. The effect of quenching and factors such as types of counting vials, extractive reagents and composition of extractive scintillation cocktail on alpha spectral resolution, was experimentally studied.

Application of simulated standard spectra for the analysis of complex sample spectra from NaI(Tl) detectors

The most accurate method for the analysis of complex gamma ray spectra from scintillation detectors is least squares method. The major requirement of this method is individual standard spectra of all nuclides expected in the complex spectrum which is not possible and feasible for some nuclides. In the present work, an approach of using simulated standard spectrum of the radionuclides for the least squares analysis is studied. The paper describes the methodology used for the generation of simulated spectrum which is the main objective, and validation of results using standard sources in the Sodium Iodide (NaI(Tl)) based gamma ray spectrometer.

Direct estimation of 90Sr in water samples of spent fuel storage bay using partial counting rate technique

The direct estimation of 90Sr by β counting from a mixture of other β and γ emitter is often difficult due to the efficiency variation among the β-emitters and the unknown nature of the sample. This paper deals with use of a combination of β and γ spectrometry measurements in estimating the activity of 90Sr, pure β emitter from a mixture of other β–γ emitters in water samples. This procedure offers a simple, easy to use, rapid and a reliable method for 90Sr estimation as an alternative to the tedious radiochemical separation procedure in this specific case.

Bulk laundry monitoring system

Protective wear (like boiler suits, hand gloves etc.) is necessary while handling radioactive material in plants/laboratories. During the course of work, it is quite possible that protective wear may get contaminated. These protective wear are packed in laundry bags and send to Decontamination Centre (DC) for washing. There is a need for monitoring the laundry bags at the time of receipt, as well as before dispatch to respective locations to comply with AERB guidelines. To avoid cross contamination during wash cycle, contaminated bags (>0.5 mR/h on surface) need to be segregated. Present paper describes the development of such system for monitoring surface dose rate on bags at the time of receipt.

Performance of LaCl 3 detector for environmental radioactivity measurements

Assessment of natural radioactivity in the environment using gamma spectrometry is common method. NaI (Tl) detectors and HPGe detectors are used for gamma spectrometry in general. The recent arrival of Lanthanum Halide detectors have better resolution compared to NaI (Tl) detectors. In the present work, the performance of Lanthanum Chloride (LaCl 3 ) detector for the natural radioactivity estimation is studied and compared with NaI (Tl) and HPGe detectors.