NISCAIR Online Periodicals Repository Collection: IJPAP Vol.50(07) [July 2012]

Device for mechanoluminescence excitation by applying gradually varying pressure on the sample

Title: Device for mechanoluminescence excitation by applying gradually varying pressure on the sample

Authors: Rai, R K; Kher, R S; S A, Khan; Dhoble, S J; Upadhyay, A K

Abstract: A low cost set-up has been designed and developed for producing mechanoluminescence (ML) by continuously varying pressure on the sample. The ML of γ-irradiated BaAl₂O₄:Eu phosphor has been studied. ML is excited impulsively by dropping a load through guiding cylinder and by applying continuously varying pressure on the sample. When BaAl₂O₄:Eu phosphor is deformed impulsively, a single peak with shoulder is observed in the time versus ML intensity curve, while number of peak is observed when continuously increasing pressure applied on to the sample. When pressure is continuously decreased less number of peaks is observed as compared to that of increasing pressure. The enhancement in ML intensity with γ-irradiation suggests that BaAl₂O₄:Eu is a suitable candidate for ML dosimetry.

Page(s): 534-537

Angular distribution of the ambient neutron dose equivalent from incidence of alpha particles on thick Al target

Title: Angular distribution of the ambient neutron dose equivalent from incidence of alpha particles on thick Al target

Authors: Shanbhag, A A; Tripathy, S P; Sahoo, G S; Sunil, C; Nandy, M; Sarkar, P K

Abstract: In this study, the measured data of angular distribution of neutron dose equivalent due to neutrons arising from the bombardment of 19.8 and 30 MeV alpha particles on a thick aluminium target has been reported. These measurements have been carried out at the BARC-TIFR Pelletron Linac Accelerator Facility using neutron dose equivalent meters popularly known as REM meters. The neutron dose equivalent values measured at a distance of 1 m from the target at various angles relative to the incident beam direction are presented here. The values are compared with those predicted by the empirical formulation of Clapier & Zaidins.

Page(s): 531-533

Shield design for a hull neutron monitor using Monte Carlo techniques

Title: Shield design for a hull neutron monitor using Monte Carlo techniques

Authors: Anand, S; Singh, Kapil Deo; Sharma, V K

Abstract: In the head-end process of a reprocessing plant, the spent fuel is chopped using a mechanical chopper into small pieces and the heavy metal oxide is leached in nitric acid leaving behind the undissolved zircaloy clad (hull) in the basket. The hull mass needs to be estimated for the residual actinides and fission products to check for the completion of dissolution and also for the purpose of nuclear material accounting. This is normally carried out by gamma spectroscopy for the residual fission products. A new method is proposed based on active/passive neutron measurements of the residual actinides. The basket along with the hull is moved to a corner of the dissolution cell using remote tools, where the hull monitoring exercise will be carried out. Hence, shielding around this basket is required in this area to limit the dose rate to a value acceptable (i) for the operating personnel engaged in monitoring, and (ii) for ³He detectors used to measure neutrons. It has been proposed that the acceptable dose rate criteria at this detector location should be less than 1.74 mGy/hr (200 mR/hr). ORIGEN2 code is used to calculate the gamma and neutron emission rate from the residual spent fuel and the clad material in the hulls. Shielding code based on Monte Carlo technique is used for the gamma and neutron shielding calculations. In this paper, calculations are carried out for each of the shield material considered, and it is found that the shielding thickness required to bring down the dose rate to 1.74 mGy/hr is 12.5 cm for lead or 21 cm for iron.

Page(s): 527-530

Comparison of methodologies of gamma ray spectrometer and X-ray fluorescence

Title: Comparison of methodologies of gamma ray spectrometer and X-ray fluorescence

Authors: Cunha, P D; Narayana, Y

Abstract: Gamma-ray spectrometric analysis is often considered as an ideal method for thorium analysis, which would otherwise require the use of more tedious, time consuming and often less precise chemical methods. With the development of rare earth research, X-ray fluorescence spectrometry analysis has become an important means of rare earth elements analysis and has been playing an increasingly important role. In the present study, the XRF-spectrometry and gamma-spectrometric techniques have been carried out in determining the concentration of thorium in monazite bearing sand samples. Monazite is the principal source of thorium and the rare earth elements but its composition and the distribution may vary within very wide limits. Both XRF and Gamma-ray spectrometry techniques use uncharged radiation, although of different in origin, to identify and estimate concentrations of elements present in the sample. However, the XRF method is much quicker and the amount of sample needed for analysis is much less compared to gamma spectrometry analysis. The correlation study of the results obtained by these two methods was analysed and compared.

Page(s): 524-526