Variation of neutron flux and related parameters in an irradiation container, in use with k0-based neutron activation analysis

1992 ◽  
Vol 157 (2) ◽  
pp. 301-312 ◽  
Author(s):  
P. Bode ◽  
M. Blaauw ◽  
I. Obrusník
2013 ◽  
Vol 101 (9) ◽  
pp. 601-606
Author(s):  
M. Wasim

Summary Miniature neutron source reactors (MNSR) are known for their stable neutron flux characteristics and are mostly employed for neutron activation analysis (NAA). Interfering reactions are sometimes observed in instrumental neutron activation analysis (INAA). Failure to correct for these interferences produces significant systematic positive errors. This paper provides correction factors for the interferences caused by the threshold reactions and fission products of 235U. These factors were calculated by using the experimentally determined thermal, epithermal and fast neutron flux and epithermal neutron flux shape factor and the nuclear data from the literature using the Høgdahl convention. Correction factors were calculated for (n, p) and (n, α) reactions for the most commonly observed radionuclides in INAA. Similarly, correction factors for uranium fission were calculated for 9 elements (Ce, Ba, La, Mo, Nd, Pd, Ru, Sm and Zr). The correction factors were validated by analyzing different materials. A comparison of uranium fission factors with those published in the literature showed a good agreement except for 97Zr, 99Mo and 131Ba which is due to difference in the flux characteristics. In general, these factors can be used with confidence.


Author(s):  
Wellington Ferrari Da Silva ◽  
Maria Ângela de B. C. Menezes ◽  
Douglas José Marques

Corn cultivation for silage requires special soil management and constant applications of fertilizers and agricultural pesticides to achieve satisfactory yield levels. This study was carried out on a farm that has grown corn for several years. The soil does not have adequate management in terms of fertility and fertilization. The matrices collected were soil, roots, leaves and grains in a corn silage area to investigate which chemical elements are present and their concentrations. The neutron activation analysis (NAA) by k0-standardization method was applied on elemental concentration determination. In this technique, the sample is submitted to a neutron flux, in order to produce radioactive isotopes of the nuclei present in the original sample. In the k0 method, the sample is irradiated together with a neutron flux monitor, usually gold (Au), in the same irradiation position and standards of the interested element are not necessary. Several samples can be irradiated simultaneously when stacked inside the irradiation vessel, intercalated with neutron flux monitors. The irradiations were carried out in the TRIGA MARK I IPR-R1 research reactor at Nuclear Technology Development Centre/Brazilian Commission for Nuclear Energy (CDTN / CNEN). In the analysis, As, Ba, Br, Ca, Ce, Co, Cr, Cs, Cu, Eu, Fe, Hf, K, La, Mo, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn were identified in the samples. Although the site studied lacks adequate management of soil fertility and fertilization, Ca, Cu, K, Mo and Zn were determined and their presences are important because they are essential for corn development. Adequate content for the cultivation of silage corn were verified by assessing these nutrients and their translocation in the plant.


2015 ◽  
Vol 103 (9) ◽  
Author(s):  
Alimardon V. Rakhimov ◽  
Viktor B. Brudanin ◽  
Dmitry V. Filosofov ◽  
Pia Loaiza ◽  
Genko M. Marinov ◽  
...  

AbstractInstrumental neutron-activation analysis (INAA) was applied to estimate trace contaminations in polyethylene (PE) used as a neutron shield for low background setup of the EDELWEISS Dark Matter search experiment. PE samples with masses of 1–10 grams each were irradiated at the WWR-SM nuclear reactor by neutron flux of 1 · 10


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