Title: Background minimisation of HPGe detector by passive graded shielding

Authors: Vishwanath P. Singh; D.D. Veerendra; B.N. Dileep; Q. Sheikh; S.S. Managanvi; N.M. Badiger; H.R. Bhat

Addresses: Health Physics Section, Kaiga Generating Station 3&4, NPCIL, Kaiga 581400, Karnataka, India; Department of Physics, Karnatak University, Dharwad 580003, Karnataka, India. ' Health Physics Section, Kaiga Generating Station 3&4, NPCIL, Kaiga 581400, Karnataka, India. ' Environmental Survey Laboratory, Health Physics Division, BARC, Kaiga, Karnataka, India. ' Health Physics Section, Rawatbhata Atomic Power Station 1&2, NPCIL, Kota 312901, India. ' Health Physics Section, Kaiga Generating Station 3&4, NPCIL, Kaiga 581400, Karnataka, India. ' Department of Physics, Karnatak University, Dharwad 580003, Karnataka, India. ' Nuclear Power Corporation of India Limited, Mumbai 400095, India

Abstract: A simple and economical passive graded shielding which is combination of low and high Z materials for HPGe detector for background radiation minimisation is developed for better identification of the peaks in acquired spectrum by reducing Compton continuum. The present paper discusses the design and advantages of the passive graded shielding (lead + copper + aluminium) which encloses the HPGe detector. The passive graded shielding improved sensitivity of the detector and reduced Minimum Detectable Activity (MDA) for planchet source from 19.6% to 11.7% for gamma photon energies in the range of 81-1408 keV and brought down the MDA, 35.25 GBq d−1 and 35.26 GBq d−1 for 133Xe and 135Xe respectively which was 72.31 GBq d−1 and 78.27 GBq d−1 for noble gases in gaseous effluents before shielding of the detector. The passive graded shielding as integral part is considerably very useful for radiological protection at nuclear power/research reactors by minimising background radiation.

Keywords: HPGe detectors; background radiation; passive shielding; MDA; minimum detectable activity; graded shielding; continuum; gaseous effluent; integral; FPNG; stack; low radiation; lead; copper; aluminium; radiological protection; nuclear power plants; NPP; nuclear energy.

DOI: 10.1504/IJLR.2011.046530

International Journal of Low Radiation, 2011 Vol.8 No.4, pp.313 - 328

Published online: 07 Feb 2015 *

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