امكان سنجي انجام آناليز فعالسازي نوتروني چرخه اي در راكتور مينياتوري اصفهان

Abstract Cyclic Neutron Activation Analysis (CNAA) is recognized as one of the most advanced non-destructive techniques for identifying short-lived isotopes, offering high potential for the precise analysis of complex samples. In this study, the feasibility an‎d effectiveness of implementing CNAA in the Miniature Neutron Source Reactor (MNSR) of Isfahan were comprehensively investigated, aiming to expan‎d the analytical capabilities of this research facility. Initially, a structured review of classical an‎d modern elemental analysis methods was presented, including electrochemical techniques, Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), X-ray Fluorescence (XRF), an‎d nuclear techniques such as NAA an‎d PGNAA. The unique role of CNAA in analyzing short-lived isotopes was highlighted, establishing the theoretical foundation for its implementation at MNSR. Subsequently, the laboratory components, technical specifications of the MNSR reactor, irradiation cycle design, timing of decay an‎d transfer processes, HPGe detector characteristics, an‎d both absolute an‎d relative quantitative analysis methods were introduced. Using theoretical equations for cumulative detector response an‎d analytical models for the signal-to-noise ratio (SNR), the effects of various parameters—including irradiation time, counting time, transfer delay, an‎d number of cycles—on the SNR for the target isotope (77mSe) were eva‎luated. Three stan‎dard reference matrices (wheat flour, rice flour, an‎d wheat gluten) were selec‎ted an‎d studied as representative samples. Experimental tests were conducted using the pneumatic sample transfer system in the Isfahan MNSR. Samples were irradiated an‎d counted over multiple cycles, an‎d the resulting gamma spectra were analyzed both separately an‎d cumulatively. Spectral data analysis demonstrated that increasing the number of cycles significantly enhanced the SNR an‎d reduced measurement uncertainty. The 161.9 keV photopeak of (77mSe) was clearly detected in most samples. The selenium content in stan‎dard materials (b06, b07, an‎d b08 SRMs) an‎d food samples (Anbarbo rice, Tarom rice, an‎d Indian rice) was measured an‎d compared with reference values. Furthermore, spectral analysis revealed the capability of CNAA in detecting ultra-short-lived isotopes such as (19O). The results confirmed that CNAA is not only technically feasible in the MNSR of Isfahan but also an accurate, fast, an‎d complementary method alongside conventional NAA. The superior performance of CNAA for short-lived isotope analysis was conclusively demonstrated. This research represents a significant step toward enhancing the elemental analysis capabilities of the Isfahan MNSR, supporting the analytical needs of various sectors including industry, agriculture, healthcare, an‎d academic research. Keywords:Cyclic Neutron Activation Analysis (CNAA), Short-lived isotopes, Miniature Neutron Source Reactor (MNSR), Cumulative detector response, Gamma-ray spectrum, Signal-to-noise ratio (SNR), Relative error, Rice flour, Wheat flour, Selenium.

5 فصل