Ultrasonic measurement of gap between calandria tube and liquid injection shutdown system tube in PHWR

Sag of CT or liquid injection shutdown system tubes in pressurized heavy water reactor is known to occur due to irradiation creep and growth during plant operation. When the sag of CT is big enough, the CT tube possibly comes in contact with liquid injection shutdown system tube (LIN) crossing beneath the CT, which subsequently may prevent the safe operation. It is therefore necessary to check the gap between the two tubes in order to confirm no contacts when using a proper measure periodically during the plant life. An ultrasonic gap measuring probe assembly which can be fed through viewing port installed on the calandria was developed and utilized to measure the sags of both tubes in a pressurized heavy water reactor in Korea. It was found that the centerlines of CT and LIN can be precisely detected by ultrasonic wave. The gaps between two tubes were easily obtained from the relative distance of the measured centerline elevations of the tubes. But the measured gap data observed at the viewing port were actually not the data at the crossing point of CT and LIN. To get the actual gap between two tubes, mathematical modeling for the deflection curves of two tubes was used. The sags of CT and LIN tubes were also obtained by comparison of the present centerlines with the initial elevations at the beginning of plant operation. The gaps between two tubes in the unmeasurable regions were calculated based on the measurement data and the channel power distribution.     

Analysis of one-dimensional pressure pulse propagation in a closed fluid system

This paper describes a unique numerical method for linear inviscid fluid hammer analysis based on the method of characteristics. The uniqueness lies in that it uses the analytical solutions of the wave equation in place of the compatibility relatins of the more conventional method of characteristics. The numerical solution is obtained by a simple superposition technique for tracing the waves traveling along each characteristic and extending the solution from one constant time line to the next. Using a predetermined finite difference net of grids with equal spacings, an elimination is made of the spatial interpolation, thereby maintaining the wave amplitudes in their full strength in the numerical procedure. This is in contrast to the case of a nonlinear problem in which the pressure peaks are always flattened to some degree in the interpolation procedure.The computer program NAHAMMER is a system analysis code adequate for short-term pressure transients of most engineering problems of significance involving a moderate pressure source. It considers the simplified one-dimensional, linear, inviscid set of governing equations with an isentropic flow assumption. A closed fluid-network system is considered to be composed of a multiple of one-dimensional pipe sections and components that are connected by various joints. An analytical solution is obtained under an acoustic approximation for a simple system and the result shows good agreement with the numerical solution. As examples of the application of the method, complex problems of engineering importance are calculated and the results are presented.     

Energy consumption analysis of the pressure control system in the primary loops of a PHWR (pressurized heavy water reactor)

In recent development of CANDU type reactors, a low vapor quality is found allowable in the hot side primary coolant. Since the void fraction is adequately low under operation pressure, parameters in reactivity control aspects do not much deviate from the case of subcooled coolant. Both coolant inventory and pressure control can be accomplished by feed-and-bleed devices in a subcooled system. As the saturated phases appear, a surge tank is usually necessary for the pressure control.Quantitative formulations in energy consumption for the pressurizing and depressurizing processes in both feed-and-bleed and surge tank systems are derived as functions of the system pressure or the corresponding saturation temperature. Consequently, one may suggest that the liquid bleed valves should be scheduled less active than the vapor bleed valves for energy conservation.     

Non reflecting boundary conditions and their use in estimating the effects of coolant channel failure in a PHWR

Non reflecting boundary conditions are applied to the truncation boundary of large domains to restrict the domain to a small region of interest from which waves travel only outwards. In this paper, this procedure is used to calculate the pressure field in the moderator of a pressurized heavy water reactor after a coolant channel has failed. Non reflecting boundary conditions are applied to the moderator boundary while a perfectly reflecting boundary is assumed for the channels.     

Characteristics of the beam injection system in an electron LINAC

The main characteristics of an electron beam injection system are described; the system is used for injecting and focusing electron beams into the acceleration structure of an 10 MeV linear electron accelerator. The beam injection system consists of a Pierce convergent diode-type electron gun with pulse modulator for power supply and a thin axially symmetric lens. The perveance and the capture coefficient were optimized by the analogical resistors network. This type of injection system was used in the linear electron accelerators: ALIN - 3 MeV, ALIN - 10 MeV and ALID − 8 MeV, performed at NILPRP^∗ Bucharest, Romania.     

Commissioning of the first KSTAR neutral beam injection system and beam experiments

The neutral beam injection (NBI) system was designed to provide plasma heating and current drive for high performance and long pulse operation of the Korean Superconducting Tokamak Advanced Research (KSTAR) device using two co-current beam injection systems. Each neutral beam injection system was designed to inject three beams using three ion sources and each ion source has been designed to deliver more than 2.0 MW of deuterium neutral beam power for the 100-keV beam energy. Consequently, the final goal of the KSTAR NBI system aims to inject more than 12 MW of deuterium beam power with the two NBI for the long pulse operation of the KSTAR. As an initial step toward the long pulse (～300 s) KSTAR NBI system development, the first neutral beam injection system equipped with one ion source was constructed for the KSTAR 2010 campaign and successfully commissioned. During the KSTAR 2010 campaign, a MW-deuterium neutral beam was successfully injected to the KSTAR plasma with maximum beam energy of 90 keV and the L-H transition was observed with neutral beam heating. In recent 2011 campaign, the beam power of 1.5 MW is injected with the beam energy of 95 keV. With the beam injection, the ion and electron temperatures increased significantly, and increase of the toroidal rotation speed of the plasma was observed as well. This paper describes the design, construction, commissioning results of the first NBI system leading the successful heating experiments carried in the KSTAR 2010 and 2011 campaign and the trial of 300-s long pulse beam extraction.     

On the decrease of the ion pulse duration and ion pulse rate in a cyclotron

Results of calculations and experiments dealing with shortening of the duration of ion pulses on the target of a cyclotron are presented. The possibility of changing the ion pulse rate by deflecting with a high frequency potential applied to an electrode inside the dee, which draws off the ions on the first half turn is discussed.Calculations and experiments were made for the condition of deuteron acceleration up to 10 Mev in the one and one-half meter cyclotron [1].The authors deeply thank N. A. Vlasov, S. P. Kalinin, B. V. Rybakov, and V. A. Sidorov for sustained interest in the work and their joint discussion of it; N. I. Chumakov, V. P. Konyaev, and G. N. Golovanov for making a series of calculations; Yu. V. Korshunov, A. V. Antonov, and E. A. Meleshko for the deisgn and adjustment of the electronic apparatus for the control electrode supply.     

Thermohydraulic characteristics and critical thermal loads in the beam collectors of the T-15 injection system

Republic Science Center "Kurchatov Institute." Translated from Atomnaya Énergiya, Vol. 72, No. 6, pp. 580-587, June, 1992.     

Qualitative response of safety injection system for a large size break in the reactor coolant system cold leg

Safety injection system, accumulator injection system and residual heat removal system of CHASNUPP-1 were simulated using the computer code APROS. We observed the qualitative response of the simulated system during injection and re-circulation phases after LOCA. During rapid depressurization of SRC system due to leakage, these systems started coolant injection in the SRC system as per plant requirement. Different thermal-hydraulic parameters of the respective systems are presented and discussed. Results obtained are in good agreement with the reported document of the reference power plant.     

电流注入法模拟双电缆系统的X光辐照效应实验研究

在简要介绍屏蔽电缆的转移阻抗和转移导纳耦合的基础上,描述了利用三同轴系统对双电缆和等效负载组成的电缆系统进行电流注入,模拟电缆屏蔽层发射电流,测量芯线等效负载感应信号的实验,给出实验结果及分析,并对理论结果与实验进行了比较。     

Computational investigations of the dynamical characteristics of the core of a periodic pulse reactor in a system with cascade neutron multiplication

The core dynamics of a fast reactor in a cascade reactor system operating in a periodic-pulse regime are examined. A model of a BN-600 fuel element is used as a computational model. Computational studies of the neutron kinetics processes in a fast rector-subcritical assembly system and the thermal dynamics of a fuel element in the core of a periodic-pulse reactor are performed. Estimates are made of the service life of a fuel element operating in a regime with repeating pulses and a number of heat loads that is admissible from the standpoint of the fatigue strength of the element.Translated from Atomnaya Ènergiya, Vol. 97, No. 4, pp. 260–269, October, 2004.     

A method of measuring the mean charge in a pulse and an estimate of the limit pulse sensitivity of a fission chamber

A physical-mathematical justification and an experimental verification of an improved method of measuring the mean charge in a pulse and the limit pulse sensitivity of neutron fission ionization chambers are presented. All-Union Scientific Research Institute of Theoretical Physics and Astronomy. Translated from Atomnay énergiya, Vol. 86, No. 6, pp. 457–460, June, 1999.     

The Greuling–Goertzel and Wigner approximations in the theory of neutron slowing down

The classic Greuling–Goertzel and Wigner approximations for neutron slowing-down problems are reappraised theoretically and numerically. We sketch the standard derivations of these approximations and show that, contrary to conventional wisdom, their theoretical bases are comparable. We also present a new derivation of these approximations, which clarifies the relationship between them and the Fermi age approximation. Finally, we compare numerical solutions of the exact, Greuling–Goertzel, and Wigner equations. These results show that for narrow absorption resonances described by the Breit–Wigner formula, the Wigner solution is significantly more accurate than the Greuling–Goertzel solution.     

Use of spar elements to stimulate fluid acoustical effects and fluid-solid interaction in the finite element analysis of piping system dynamics

A technique is presented for using existing options in structural analysis finite element computer programs to simulate fluid acoustical effects and fluid-structure interaction in piping system dynamic analysis. With this technique, the fluid in straight pipe section is represented as a sequence of spar elements coupled to the pipe motion in the transverse direction but free to move independently in the axial direction. Special modeling considerations for treating the acoustical and fluid-structure interaction effects at elbows, tees and area changes are also derived. Results using this kind of modeling are presented for a pulse loading of a leg of piping with the same cross-sectional dimensions and elbow radii as the Clinch River Breeder Reactor Plant (CRBRP) primary piping.     

Changes in trace elements of cerebrospinal fluid after subarachnoid hemorrhage, and effects of trace elements on vasospasm

Various causal factors have been proposed for cerebral vasospasm after subarachnoid hemorrhage (SAH), such as serotonin, acetylcholine, angiotensin, thrombin and thromboxane A2. However, none of them explain the whole pathomechanism of vasospasm. To evaluate the role of trace elements on vasospasm, we have examined these sequential changes in the cerebrospinal fluid (CSF) after SAH by PIXE, and have investigated the relation between trace elements and vasospasm. We obtained the CSF samples from cisternal drainage in patients with SAH who underwent radical surgery within 48 h from the onset. The drainage was placed into basal cisterns at the end of the operation. Three sampling times (3–5, 7–9 and 12–14 days from the onset) has been scheduled because vasospasm is likely to occur from day 4 to day 14 after the onset. In this study, we focused on the levels of Mg, Ca, Mn, Al, Zn, P, Pb, Sr, Br, Co, Cu, Si, Ti, Mn,Co, Cu, Zn, Br, Sr, Mo and Pb, and we found a significantly lower level of Mg in the CSF of patients with vasospasm on days 7–9 after the onset. These results suggest that Mg in the CSF may ameliorate vasoconstriction due to Ca in the pathomechanism of vasospasm.