Authors & Affiliations

Dolgikh V.P., Koscheev V.N., Kriachko M.V., Yakunin A.A.
A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia

Dolgikh V.P. – Researcher, A.I. Leypunsky Institute for Physics and Power Engineering.
Koscheev V.N. – Leading Researcher, Cand. Sci. (Phys.-Math.), A.I. Leypunsky Institute for Physics and Power Engineering.
Kriachko M.V. – Researcher, A.I. Leypunsky Institute for Physics and Power Engineering.
Yakunin A.A. – Researcher, A.I. Leypunsky Institute for Physics and Power Engineering.

Abstract

The reliability of the calculated values of the non-fuel compositions and structural elements radiation characteristics (including structural elements of the fuel assemblies and non-fuel compositions of the core) directly affects on the evaluation of the structural elements activity, and, consequently, the development of approaches to structural assemblies handling during their processing, transportation, storage and burial.
In addition to iron, structural elements of assemblies and non-fuel compositions include impurity elements: Cr, Mn, Co, Ni, Nb, Mo, etc., which significantly influence on the radiation characteristics of the structural elements of the core assemblies. Their activity directly affects on the category of radioactive waste, which, in turn, affects on the cost parameters when handling and dumping radioactive waste.
For nuclides, the activation of which makes the main contribution to the activity of structural elements assemblies and non-fuel compositions at different holding times, there arises a primary need for determining the reliability of the neutron capture cross section. The selected list of nuclides, the most important from this point of view, includes: 54Fe, 59Co, 62Ni.
The traditional approaches to verification of nuclear data on the simplest integral "standard" spectra (the value of the cross section at the thermal point, the resonant capture integral of RIC) do not provide an opportunity to reliably estimate the quality of the nuclear data used for structural nuclides in the resonance energy region.
The fact is that the first resonance levels on structural nuclides are located in the energy range about ~1.0 keV, i.e. in the energy range in which the contribution of the capture cross section to the resonance integral is already negligible. Additional evaluation criteria are needed to assess the reliability of the capture cross section in the resonance region.
The KADoNiS database of astrophysical data was used for this purpose. It contains the recommended values of the neutron capture cross section (MACS) averaged with the weight of the Maxwell spectrum in the temperature range from 5 to 100 keV for isotopes participating in nuclear nucleosynthesis.
The recommended values were obtained on the basis of experiments performed by different methods. Using the Maxwell spectrum for such a range of spectral temperatures makes it possible to estimate the reliability of nuclear data in the resonance region up to ~1 MeV.
The conclusions were drawn regarding the reliability of the capture cross section based on the verification of the capture cross-section from various nuclear data sources for the nuclides listed above.

Keywords
reactor of high power, the structural elements activity, the radiation capture cross section, verification of the cross section estimation reliability, the astrophysical base experiments KADoNiS

Article Text (PDF, in Russian)

References

UDC 621.039.7

Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants", 2018, issue 3, 3:2