Analytical model for determining the leakage albedo component for a direct cylindrical channel passing through the nuclear reactor protective layer

The task of determining the radiation situation, including neutron and gamma-quantum flux density, radiation spectrum, specific volumetric activity of radioactive gases in the air, etc. behind the protective composition having inhomogeneities, has always been important in matters of radiation safety. One of the ways to solve the problem of determining gamma radiation fluxes was to divide the total ionizing radiation flux into four components: line-of-sight (LOS), leakage, line-of-sight albedo, and leakage albedo, and obtain an analytical solution for each component. The first three components have been studied in detail in relation to simple geometries and there are analytical solutions for them, but there is no such a solution for the last component. The authors of this work have derived an analytical representation for the leakage albedo component, which, in contrast to numerical methods (such as Monte Carlo methods), makes it possible to analyze the effect of inhomogeneities in protective compositions on the radiation environment as well as to quickly obtain estimated values of fluxes and dose rates. Performing a component-by-component comparison, it becomes possible to single out the most significant mechanisms of the dose load formation behind the nuclear reactor protection, to draw conclusions about the effectiveness of design solutions in the protection design and to improve the protection at significantly lower computational costs. Finally, the authors present calculations for the four components of the total ionizing radiation flux for various parameters of the cylindrical inhomogeneity in the reactor protection. Based on the obtained values, conclusions are made about the importance of taking into account the leakage albedo component in the formation of the radiation situation behind the core vessel.

CROSS-SECTIONS OF PHOTONUCLEAR REACTIONS ON natМо TARGETS AT END-POINT BREMSSTRAHLUNG ENERGY UP TO Еγmax = 100 МeV

Experiments to determine the yields and bremsstrahlung flux-averaged cross-sections σ(Еγmax) of photonuclear reactions on the natural Mo targets were performed on the beam from the electron linear accelerator LUE-40 with the use of the γ-activation technique. The bremsstrahlung end-point energies were in the range Еγmax = 35…80 MeV. The bremsstrahlung quantum flux was calculated with the program GEANT4.9.2 and, in addition, was monitored using the 100Мо(γ, n)99Мо reaction. Calculations of the yields and average cross-sections σ(Еγmax) for photonuclear reactions on stable Mo isotopes were computed using the σ(Е) cross-sections from the TALYS1.95 code (for the level density model LD1). A comparison of experimental and calculated cross-sections σ(Еγmax) for reactions 92Мо(γ, 2n)90Мо and 92Мо(γ, pn)90Nb was performed.

Times of arrival and gauge invariance

We revisit the arguments underlying two well-known arrival-time distributions in quantum mechanics, viz., the Aharonov–Bohm–Kijowski (ABK) distribution, applicable for freely moving particles, and the quantum flux (QF) distribution. An inconsistency in the original axiomatic derivation of Kijowski’s result is pointed out, along with an inescapable consequence of the ‘negative arrival times’ inherent to this proposal (and generalizations thereof). The ABK free-particle restriction is lifted in a discussion of an explicit arrival-time set-up featuring a charged particle moving in a constant magnetic field. A natural generalization of the ABK distribution is in this case shown to be critically gauge-dependent. A direct comparison to the QF distribution, which does not exhibit this flaw, is drawn (its acknowledged drawback concerning the quantum backflow effect notwithstanding).

Effects of Cornell-type scalar potential on a generalized KG-oscillator field in Kaluza–Klein theory

We study a generalized KG-oscillator in the five-dimensional cosmic string geometry background with a magnetic field and quantum flux using Kaluza–Klein theory under the effects of a Cornell-type scalar potential, and observe the gravitational analogue of the Aharonov–Bohm effect. We see that the scalar potential allows the formation of bound states solution, and the energy eigenvalue depends on the global parameter characterizing the space–time. We also see that the magnetic field depends on quantum numbers of the relativistic system which shows a quantum effect.