Characterization of Irradiation Sites of Apsara Reactor for $k_{0}$-Based IM-NAA and Its Validation and Application

Abstract

Three irradiation positions of Apsara reactor were characterized by determining epithermal neutron spectrum shape factor <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$(\alpha)$</tex></formula> and sub-cadmium to epithermal neutron flux ratio <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$(f)$</tex> </formula> for <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm k}_{0}$</tex> </formula> -based Internal Monostandard Neutron Activation Analysis (IM-NAA). The <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\alpha$</tex></formula> values were determined by cadmium ratio method using six neutron flux monitors (In, Au, Co, Mo, Zn and Zr). The <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$f$</tex> </formula> -value was also determined by cadmium ratio method using an Au monitor. The <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\alpha$</tex></formula> values of two irradiation positions are found to be positive, which indicated softened epithermal neutron spectra whereas <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\alpha$</tex> </formula> value of the third one is negative indicating hardened neutron spectrum. IAEA reference material, RM SL-1 (Lake Sediment) was analyzed by IM-NAA using experimentally determined <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$f$</tex></formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\alpha$</tex></formula> values of all three irradiation positions. A total of 16 elemental concentrations were determined using Sc as the internal monostandard and the values are found to be in good agreement with respect to the certified or information values. As an application of IM-NAA, two ceramic archaeological samples along with one soil sample were analyzed using Sc as the monostandard.