# On the use of solution to the adjoint inhomogeneous transport equation in determining parameters of multiplying media

12/25/2015 2015 - #04 Physics and technology of nuclear reactors

Grabezhnoy V.A. Doulin V.A. Doulin V.V.

https://doi.org/10.26583/npe.2015.4.12

### UDC: 621.039.519.4

The measurements to determine the weight of the block and the part of plutonium contained therein 239Pu made were done by the detector AWCC - Active Well Coincidence Counter. The using of a known point model can not determine the value of effective neutron multiplication factor for subcritical block appreciable size or mass and the part they contain 239Pu, because the efficiency detection of the neutrons depends on their production place (spatial effects). Analysis of the measurements for results of double and triple neutron-neutrons coincidence carried out taking into account the spatial effects. The solution of the homogeneous quasi-critical transport equations and the solutions of the inhomogeneous adjoint transport equation were used to clarify the definitions of efficiency detection neutrons as appearing only on the spontaneous fission, and taking into account their multiplication in the blocks at the same time. The value of the effective multiplication factor in the single-core subcritical assembly BFS-73 was determined by these methods and compared with the standard method ORUK, based on inverted solution of kinetics equation. The aim of the work was to determine the preference of these three definitions of efficiency for the analysis of measurement results. It was been shown the unsuitability of the homogeneous quasi-critical equations solutions for the analysis of very deep subcriticalities as solutions of the adjoint inhomogeneous equation does not take into account the neutron multiplication near criticality.

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neutron detectors method of neutron coincidence neutron detection efficiency determine the mass of plutonium and enrichment effective multiplication factor