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  • Author or Editor: Tran Van Hung x
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Abstract  

The α-factor is a measure of the epithermal neutron flux deviation from the ideal distribution 1/E, where E is neutron energy. It defends on the position of the irradiation channel in reactor. A determination method of the α-factors in irradiation channels of Dalat reactor is presented by fitting the epithermal neutron spectrum obtained from the calculation using MCNP code. The fitting α-values were compared to those by experiment used the “Cd-ratio” method with monitors 197Au–94Zr and 197Au–64Zn. It shows that the α-values calculated from neutron spectra agree well with experimental ones. The difference between both data is about 6%.

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Abstract  

A modified method has been developed for the α determination in the 1/E 1+α epithermal neutron spectrum of reactor. It is based on the Cd-covered and without Cd-covered irradiations of two monitors. This method was applied to determine the α value in the channels of Dalat reactor and the results were compared with those obtained by the other methods. It appeared that the results of the modified method were in quite good agreement with those of other methods. It also showed that the modified method was simple in practical uses and a good application in the experiment of α determination in the reactor irradiation channels.

Open access

Abstract  

The neutron temperature is a characteristic parameter in irradiation channels of reactor. For nuclides which have resonances in the thermal neutron energy range, their Westcott g-factors are different from unity. The values of g-factors and cross-sections of (n, γ) reaction of these nuclides are temperature dependence. The standard energy for tabulation of thermal neutron cross-section (σ0) is that of room temperature (293.59 K or 20.43 °C), corresponding to a neutron energy 0.0253 eV or to a neutron velocity of 2200 m/s. However, in the irradiation channels of reactor, the temperature is not exact at 20.43 °C. Thus, the temperature at the irradiation position must be known to convert σ0 to σ(T). A method for determination of the neutron temperature in irradiation channels of Dalat reactor is presented by fitting the thermal neutron spectrum obtained from the calculation using MCNP code.

Open access