The epithermal neutron flux distribution in a nuclear reactor and its effect on epithermal neutron activation analysis

1978 ◽  
Vol 45 (2) ◽  
pp. 423-434 ◽  
Author(s):  
T. Bereznai ◽  
T. D. Mac Mahon
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Neutron Flux ◽  
Flux Distribution ◽  
Nuclear Reactor ◽  
Epithermal Neutron ◽  
Epithermal Neutron Flux ◽  
Epithermal Neutron Activation Analysis ◽  
Neutron Flux Distribution

Epithermal neutron activation analysis with a SLOWPOKE nuclear reactor

1981 ◽  
Vol 59 (10) ◽  
pp. 1470-1475 ◽  
Author(s):  
Donald Craig Stuart ◽  
Douglas Earl Ryan
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Nuclear Reactor ◽  
Epithermal Neutron ◽  
Instrumental Analysis ◽  
Epithermal Neutron Activation Analysis ◽  
Experimental Values ◽  
Selection Of

Epithermal neutron activation analysis is examined using a SLOWPOKE nuclear reactor. Data are given for 69 elements using cadmium and boron shielding. Cadmium ratios calculated from literature values of resonance integrals are compared with experimental values. All elements except cadmium are shielded more effectively by boron. Advantage factors for a selection of elements under cadmium, natural boron, and enriched boron shields are given. Boron shields are of particular practical value for rapid instrumental analysis.

scholarly journals Determination of uranium in tree bark samples by epithermal neutron activation analysis

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Nicole Pereira de Lima ◽  
Mitiko Saiki
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Reference Materials ◽  
Epithermal Neutron ◽  
Certified Reference Materials ◽  
Tree Bark ◽  
Good Precision ◽  
Epithermal Neutron Activation Analysis ◽  
Relative Standard

In this study uranium (U) concentrations were determined in certified reference materials (CRMs) and in tree bark samples collected in “Cidade Universitária Armando de Salles Oliveira” (CUASO) USP, São Paulo. The barks were collected from different species namely Poincianella pluviosa and Tipuana tipu. These bark samples were cleaned, dried, grated and milled for the analyses by epithermal neutron activation analysis method (ENAA). This method consists on irradiating samples and U standard in IEA-R1 nuclear reactor with thermal neutron flux of 1.9 x 1012 n cm-2 s-1 during 40 to 60 seconds depending on the samples’ matrices. The samples and standard were measured by gamma ray spectroscopy. U  was identified by the peak of  74.66 keV of 239U with half life of 23.47 minutes. Concentration of U was calculated by comparative method. For analytical quality control of U results, certified reference materials were analyzed. Results obtained for CRMs presented good precision and accuracy, with |Z score| ≤ 0.39. Uranium concentrations in tree barks varied from 83.1 to 627.6 ng g-1 and the relative standard deviations of these results ranged from 1.8 to 10 %.

Determination of thermal neutron flux distribution at the rotary rack served for elemental concentration analysis using the k0-INAA method

2021 ◽  
Vol 10 (1) ◽  
pp. 11-20
Author(s):  
Tho Nguyen Thi ◽  
Anh Tran Tuan ◽  
Cuong Trinh Van ◽  
Doanh Ho Van ◽  
Duong Tran Quoc ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Flux Distribution ◽  
Thermal Neutron Flux ◽  
Epithermal Neutron ◽  
Epithermal Neutron Flux ◽  
Irradiation Position ◽  
Neutron Flux Distribution ◽  
Sample Irradiation

The accuracy of elements concentration determination using the k0-standardization method directly depends on irradiation and measurement parameters including Non-1/E epithermal neutron flux distribution shape α (ϕ epi ≈1/E1+α ) , thermal-to-epithermal neutron flux ratio f, efficiency ε, peak area… In the case of the irradiation position at the rotary rack of the Dalat Nuclear Research Reactor (DNRR), the difference of thermal neutron flux between the bottom (3.54x1012 n.cm-2.s-1) and the top (1.93x1012 n.cm-2.s-1) of the 15 cm aluminum container is up to 45%. Therefore, it is necessary to accurately determine above-mentioned parameters in the sample irradiation position. The present paper deals with the determination of the distribution of thermal neutron flux along the sample irradiation container by using 0.1% Au–Al wire activation technique. The thermal neutron flux was then used to calculate the concentration of elements in the Standard Reference Material 2711a and SMELS type III using k0-INAA method at different positions in the container. The obtained results with the neutron flux correction were found to be in good agreement with the certified values. In conclusion, the proposed technique can be applied for activation analyses without sandwiching flux monitors between samples during irradiations.

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