NISCAIR Online Periodicals Repository Collection: IJPAP Vol.50(11) [November 2012]

Studies on optimisation of collimator thickness and aperture for hot spot identification system using Monte Carlo technique

Mon, 29 Oct 2012 22:58:59 GMT

Title: Studies on optimisation of collimator thickness and aperture for hot spot identification system using Monte Carlo technique

Authors: Verma, Amit K; Anilkumar, S; Thakur, Vaishali M; Jain, Amit; Babu, D A R; Sharma, D N

Abstract: The optimum collimator design in terms of aperture and thickness for accomplishing improved performance for wide energy radiation field has been investigated in the present paper. A 2"2" NaI(Tl) detector was used as sensor in proposed Hot Spot Identification system. The spectral response of the detector with various collimator apertures and thickness was developed using Monte Carlo methods for optimizing the collimator design. The optimum size of collimator aperture is found to be 2 mm and thickness of 5 cm. Studies were also carried out to optimize lead shield thickness around the detector.

Page(s): 874-875

Alanine-EPR dosimetry in 10 MeV electron beam to optimize process parameters for food irradiation

Mon, 29 Oct 2012 22:58:59 GMT

Title: Alanine-EPR dosimetry in 10 MeV electron beam to optimize process parameters for food irradiation

Authors: Sanyal, Bhaskar; Kumar, Sanjeev; Kumar, Mukesh; Mittal, K C; Sharma, Arun

Abstract: Absorbed dose in food product is determined and controlled by several parameters of the LINAC irradiation facility as well as those of the product. Standardization of the parameters characterizing the facility parameters, process load and the irradiation conditions collectively termed as ‘process parameters’ are important for successful dose delivery to the food products. In the present study, alanine-EPR dosimetry system was employed to optimize process parameters of 10 MeV electron beam of a LINAC facility for commercial irradiation of food products. Three sets of experiments were carried out with different food commodities namely, mango, potato and semolina (coarsely ground wheat, local name Rawa) with the available product conveying system of different irradiation geometries in one sided or two sided mode of irradiation. Three dimensional dose distributions into the process load for low dose requiring food commodities (0.25 to 1 kGy) were measured in each experiment. The actual depth dose profile in food product and useful scan width of the electron beam were found to be satisfactory for commercial radiation processing of food. Finally, a scaled up experiment with a commercial food product (packets of semolina) exhibited adequate dose uniformity ratio allowing use of the facility for large scale radiation processing of food commodities.

Page(s): 870-873

Estimation of the heat generation in vitrified waste product and shield thickness for the transportation of vitrified waste product using Monte Carlo technique

Mon, 29 Oct 2012 22:58:59 GMT

Title: Estimation of the heat generation in vitrified waste product and shield thickness for the transportation of vitrified waste product using Monte Carlo technique

Authors: Deepa, A K; Jakhete, A P; Mehta, Darshit; Singh, Neelima; Kaushik, C P; Singh, Kunjman

Abstract: High Level liquid Waste (HLW) generated during reprocessing of spent fuel contains most of the radioactivity present in entire nuclear fuel cycle resulting in need for its containment, isolation and surveillance for extended periods of time. The major components of HLW are corrosion products, fission products such as ¹³⁷Cs, ⁹⁰Sr, ¹⁰⁶Ru, ¹⁴⁴Ce ¹²⁵Sb etc, actinides and various chemicals used during reprocessing of HLW. Fresh HLW having an activity concentration of around 100 Ci/l is vitrified into borosilicate glass and contained in canisters which are placed in SS overpacks for better confinement. These overpacks contain about 0.7 million Curies of activity. For transporting the vitrified waste product (VWP), two most important parameters are shield thickness of transportation cask and heat generation in vitrified waste product. This paper describes methodology used in estimation of Pb thickness for transportation cask using the Monte Carlo technique. Using the same technique, heat generation in canister and overpack containing vitrified glass were also estimated.

Page(s): 867-869

Simulations of photoneutron spectra due to incident high energy electrons on tungsten target using FLUKA

Mon, 29 Oct 2012 22:58:59 GMT

Title: Simulations of photoneutron spectra due to incident high energy electrons on tungsten target using FLUKA

Authors: Sahani, P K; Haridas, G; Sarkar, P K

Abstract: Bremsstrahlung photons followed by photoneutrons are the major radiation hazards in high energy electron accelerators. These neutrons in high energy electron accelerator are produced by Bremsstrahlung photons through photo nuclear reactions. Monte Carlo code FLUKA was used to generate the photoneutron spectra for 20 MeV, 450 MeV and 2.5 GeV electron (electron energies in Indus facility) hitting 4 mm of tungsten target. The total photoneutron yield was calculated from the generated spectrum for different target thicknesses. The results have indicated the isotropic Giant Dipole Resonance (GDR) neutrons dominating the spectra for the above three incident electron energies. The peak energy of the neutron spectra lies between 0.1-1 MeV for these electron energies. The average neutron energy was calculated and found to be 0.82 MeV, 4.09 MeV and 11.6 MeV for 20 MeV, 450 MeV and 2.5 GeV incident electron energy, respectively. The details of the simulation and results are discussed in the paper.

Page(s): 863-866