Transforming a VVÉR-440 to a five-year fuel cycle

Kurchatovskii Institute, Russian Scientific Center. Gidropress Special Design Office. Kolskii Nuclear Power Plant. Translated from Atomnaya Énergiya, Vol. 73, No. 2, pp. 168-170, August, 1992.     

Study of a self-regulated nuclear burn wave regime in a fast reactor based on a thorium–uranium cycle

The possibility of a wave of slow nuclear burning in a fast reactor in thorium–uranium fuel cycle is investigated. The calculations were performed using a model based on the solution of a nonstationary nonlinear diffusion equation for a cylindrical homogeneous reactor using the concept of a radial geometric factor (buckling) and the effective multigroup approximation taking account of the nuclear kinetics of the precursors of delay neutrons and burnup and production of the main nuclides of the thorium–uranium fuel cycle. The calculations showed that the generation and propagation of a wave of nuclear burning traveling with velocity approximately 2 cm/yr are possible in a thorium–uranium medium. However, the addition of even small quantities of a construction material and coolant to the composition of the reactor makes it impossible to obtain the burn wave regime. A self-maintained nuclear burn regime is also established in this case and exists for a long time (∼5 yr), but the system does not transition into a regime with a nuclear burn wave propagating along the axis of the reactor.     

Prompt acceleration of a μ+ beam in a toroidal wakefield driven by a shaped steep-rising-front Laguerre–Gaussian laser pulse

Recent experimental data for anomalous magnetic moments strongly indicates the existence of new physics beyond the Standard Model. Energetic μ⁺ bunches are relevant to μ⁺ rare decay, spin rotation, resonance and relaxation (μSR) technology, future muon colliders, and neutrino factories. In this paper, we propose prompt μ⁺ acceleration in a nonlinear toroidal wakefield driven by a shaped steep-rising-front Laguerre–Gaussian (LG) laser pulse. An analytical model is described, which shows that a μ⁺ beam can be focused by an electron cylinder at the centerline of a toroidal bubble and accelerated by the front part of the longitudinal wakefield. A shaped LG laser with a short rise time can push plasma electrons, generating a higher-density electron sheath at the front of the bubble, which can enhance the acceleration field. The acceleration field driven by the shaped steep-rising-front LG laser pulse is about four times greater than that driven by a normal LG laser pulse. Our simulation results show that a 300 MeV μ⁺ bunch can be accelerated to 2 GeV and its transverse size is focused from an initial value of w₀ = 5 μm to w = 2 μm in the toroidal bubble driven by the shaped steep-rising-front LG laser pulse with a normalized amplitude of a = 22.     

Characterization of a 3-Phase a.c. Free Burning Arc Plasma

A 3-phase a.c. arc plasma reactor with large volume plasma has been developed for the synthesis of new carbon nano-structures. One of the main characteristics of the plasma system is related to the absence of a fixed neutral point. This gives rise to a rich and complex phenomenology related to instabilities and arc motion since the arcs are ＂burning＂ freely in the gas flow between the three electrodes. This paper is dedicated to the analysis of the behavior of such a system under typical conditions using argon and nitrogen as plasma gases. A classification of are configuration, arc commutating, arc interaction, arc motion and arc instabilities are discussed based on ultra high-speed cine camera analysis. A simple model describing the time evolution of the system is also presented and compared with the experimental measurements. The results show that an adequate control could allow the improvement of the overall system.     

Electron Transport Behavior in a Mirror Magnetic Field and a Uniform Electric Field

1.IntroductIOnMuchefforthasbeenpaidontheresearchabouttheglowdischargeofplasma.Low--temperatureandlow-pressuregaseousglowdischargeplasmasarewidelyusedinanumberofapplications,suchasplasmachemicalvapordeposition(PCVD),plasmaetching,plasmadisplay,gaslaser,andplasmasputtering.Someexperimentalresultshaveshownthatinglowdischargeplasmatheelectrontransportbehaviorscanbecontrolledbyamagneticfield.Fukumasaet.al.[1]showedthatmagneticfieldcouldbeusedtocontroltheelectrontransportbehaviorsindischargeplasm…     

Comparative study on the degradation of phenol by a high-voltage pulsed discharge above a liquid surface and under a liquid surface

The degradation of phenol by pulsed discharge plasma above a liquid surface(APDP) and under a liquid surface(UPDP) was compared. The effects of discharge voltage, discharge distance,initial solution conductivity and initial p H on the removal of phenol were studied. It was concluded that the removal of phenol increases with increasing discharge voltage and with decreasing discharge distance in both APDP and UPDP systems. An increase in the initial solution’s conductivity has a positive effect in...     

Use of Refractory Coatings in Systems for Melt Containment in a Serious Accident at a Nuclear Power Plant with a VVÉR Reactor

A computational analysis is performed of the use of zirconium dioxide ceramic in melt containment systems with relatively thin heat-conducting structures. The results of an investigation of the physicochemical processes for the interaction of melt with zirconium dioxide ceramic are presented. It is shown that the use of zirconium dioxide ceramic together with a passive water source gives the required melt cooling parameters for 3 to 24 h depending on the cooling regime. 4 figures, 9 references.     

Applicability of a catalytic reduction method using a palladium–copper catalyst and hydrazine for the denitration of a highly concentrated nitrate salt solution

Denitration of a highly concentrated sodium nitrate (NaNO₃) aqueous solution via a catalytic reduction method using a palladium–copper catalyst supported on carbon powder (Pd–Cu/C) and hydrazine (N₂H₄) was investigated. It was demonstrated that nitrate ion (NO₃ ^?) in a 5 mol L^?1 NaNO₃ solution was completely reduced through an intermediate nitrite ion (NO₂ ^?) to nitrogen compounds such as nitrogen, nitrous oxide, and ammonia. By comparing the reaction rates of NO₃ ^? and NO₂ ^? obtained using catalysts with various Pd–Cu compositions and different reductants (hydrogen (H₂) or N₂H₄), it was determined that the catalyst with a molar ratio of Pd:Cu = 1:0.66 provides the maximum reaction rates for NO₃ ^? and NO₂ ^? using N₂H₄, and that not only the reactions of NO₃ ^? and NO₂ ^? but also that of N₂H₄ were affected by the Pd–Cu composition.     

Synthesis of a New Amide-type Extractant

Recently, amide-type extractant is widely used for the separation of the lanthanide ion and actinide ion because of its excellent extraction capability. Tripodal ligand is a semi-rigid compound of which three side-chain could rotate freely to adapt differ…     

Synthesis of a New Amide-type Extractant

在加速器研制中，磁控管、闸流管、速调管及电子枪的灯丝都需提供稳定电压，同时电压能从零加起，缓慢上升到规定电压，不能出现突然加电情况。     

Strange Quasi-Repeller in a Kicked Rotor

A new kind of crisis was observed in a system where a transition from conservative to quasi-dissipative can be observed. The crisis signifies a sudden and intrinsic change of a stochastic web, which is formed by the end-results of the images of the discontinuous borderlines of the system function. In the crisis, a strange quasi-repeller can be defined. When changing the controlling parameter, the variation of the fractile dimension of the quasi-repeller obeys a logarithmic rule.     

镨叶绿素a分子结构的确定

通过合成镨叶绿素a(Pr-Chla)研究了稀土在叶绿素中的结合方式。Pr-Chla的紫外可见光谱（UV－Vis)、红外光谱（FTIR）证实镨离子已配位到叶绿素a的卟啉环上。其磁圆二色谱（MCD）Soret带具有双层夹心卟啉的特征结构；通过扩展X射线吸收精细结构谱（EXAFS），采用双层夹心结构模型拟合，确定了Pr周围的近邻结构。表明合成镨叶绿素a具有双层夹心结构。Pr(Ⅲ）夹于两个卟啉环之间，与上下卟啉环上共8个N原子配位，Pr-N键平均键长0.242nm。     

Gamow-Teller Resonance in a Relativistic Approach

We establish the formalism of nuclear spin-isospin excitations, especially the Gamow-Teller (GT) resonance in a fully consistent relativistic random phase approximation. A relativistic form of the Landau-Migdal parameter g'=0.6 is adopted as a residual sp…     

Experimental investigation on pressure-buildup characteristics of a water lump immerged in a molten lead pool

Motivated to understand the pressure-buildup characteristics in a circumstance of a water droplet immerged inside a heavy liquid metal pool, which is a key phenomenon during a Steam Generator Tube Rupture accident of Lead-cooled Fast Reactor,many experiments have been conducted by injecting water lumps into a molten lead pool at Sun Yat-sen University. In order to deepen the understanding of the influence of melt material, this lead experiment was compared with a Lead–Bismuth-Eutectic(LBE) exper...     

Development and simulation of a gridded thermionic cathode electron gun for a high-energy photon source

A gridded thermionic cathode electron gun was developed for the linear accelerator of the High Energy Photon Source(HEPS). An electron gun should provide a large maximum bunch charge with a wide adjustable range. To satisfy these requirements, the shape of the electrode was optimized using a multi-objective genetic algorithm. A large bunch charge with an adjustable range was achieved using the grid-limited gun, the flow of which was analyzed using 3-D simulations. The electron gun has been manuf...     

Alfvén continuum in the presence of a magnetic island in a cylinder configuration

In this work, the effect of a magnetic island on Alfvén waves is studied. A physical model is established wherein Alfvén waves propagate in the presence of a magnetic island in a cylindrical geometry. The structure of the Alfvén wave continuum is calculated by considering only the coupling caused by the periodicity in the helical angle of the magnetic island. The results show that the magnetic island can induce an upshift in the Alfvén continuum. Moreover, the coupling between different branches of the continuous spectrum becomes more significant with increasing continuum mode numbers near the boundary of the magnetic island.     

Design of a mobile neutron radiography installation based on a compact sealed tube neutron generator

A series of optimum conditions are taken into account in the construction of neutron radiography(NR) installation based on a sealed tube neutron generator capable of gnerating 10^10 n/s with 14MeV.The characteristics of NNU screens,a kind of self-made ^6LiF.ZnS(Ag)scintillation intensifying screen are presented.Finally,some neutron radiographies taken by this NR installation and NNU screens are given.     

TLD calibration and absorbed dose measurement in a radiation-induced liver injury model under a linear accelerator

The application of a thermoluminescent detector(TLD) for dose detection at the liver irradiation site in mice under linear accelerator precision radiotherapy and the use of a single high dose to irradiate the mouse liver to construct a biological model of a radiation-induced liver injury(RILD) in mice were to determine the feasibility of constructing a precision radiotherapy model in small animals under a linear accelerator. A 360° arc volumetric rotational intensity-modulated radiotherapy(VMAT)...