Specific features of the control systems of new-modification 310–330-MW steam turbines manufactured by PAO turboatom

Principal engineering solutions taken by PAO Turboatom when developing the control systems of the 310–325-MW turbines for thermal power stations are set forth. A schematic diagram of the control system is presented and the designs of the retrofitted basic mechanisms, viz., high-pressure steam-distribution unit and the cutoff valve, are described. It is noted that the accepted principles of designing the control systems allow retaining the following advantages of the latter: use of the condensate as a cheap nonflammable working fluid, valveless switches to control the locking servomotors, a mechanical ring-type turbine trip mechanism (TTM) in combination with an actuator fitted with two double-seated actuator valves to control the pressure in the pulse security lines, and a rotary valve to block the triggering of the actuator valves during successive testing of the TTM rings by filling the oil during the operation of the turbine and the subsequent raising of the above valves. The control systems of the new-modification turbines are based on microprocessor hardware using electromechanical converters to drive every cutoff valve as a universal solution that is not oriented towards a particular manufacturer of the control system electronics. Application of a mechanical turbine trip mechanism is acknowledged as indispensable for unconditional guarantee of the safe operation of the turbines irrespective of the presence of the electronic turbine trip mechanism.     

Resonant coherent excitation of hydrogen-like ions planar channeled in a crystal; Transition into the first excited state

The presented program is designed to simulate the characteristics of resonant coherent excitation of hydrogen-like ions planar-channeled in a crystal. The program realizes the numerical algorithm to solve the Schrödinger equation for the ion-bound electron at a special resonance excitation condition. The calculated wave function of the bound electron defines probabilities for the ion to be in the either ground or first excited state, or to be ionized. Finally, in the outgoing beam the fractions of ions in the ground state, in the first excited state, and ionized by collisions with target electrons, are defined. The program code is written on C++ and is designed for multiprocessing systems (clusters). The output data are presented in the table.Program summaryProgram title: RCE_H-like_1Catalogue identifier: AEKX_v1_0Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEKX_v1_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 2813No. of bytes in distributed program, including test data, etc.: 34 667Distribution format: tar.gzProgramming language: C++ (g++, icc compilers)Computer: Multiprocessor systems (clusters)Operating system: Any OS based on LINUX; program was tested under Novell SLES 10Has the code been vectorized or parallelized?: Yes. Contains MPI directivesRAM: <1 MB per processorClassification: 2.1, 2.6, 7.10External routines: MPI library for GNU C++, Intel C++ compilersNature of problem: When relativistic hydrogen-like ion moves in the crystal in the planar channeling regime, in the ion rest frame the time-periodic electric field acts on the bound electron. If the frequency of this field matches the transition frequency between electronic energy levels, the resonant coherent excitation can take place. Therefore, ions in the different states may be observed in the outgoing beam behind the crystal. To get the probabilities for the ion to be in the ground state or in the first excited state, or to be ionized, the Schrödinger equation is solved for the electron of ion. The numerical solving of the Schrödinger equation is carried out taking into account the fine structure of electronic energy levels, the Stark effect due to the influence of the crystal electric field on electronic energy levels and the ionization of ion due to the collisions with crystal electrons.Solution method: The wave function of the electron of ion is the superposition of the wave functions of stationary states with time-dependent coefficients. These stationary wave functions and corresponding energies are defined from the stationary Schrödinger equation. The equation is reduced to the problem of the eigen values and vectors of Hermitian matrix. The corresponding matrix equation is considered as the linear equation system. Then the time-dependent coefficients of the electron wave function are defined from the Schrödinger equation, with a time-periodic crystal field. The time-periodic field is responsible for the transitions between the stationary states. The final time-dependent Schrödinger equation represents the matrix equation which has been solved by means of the QR-algorithm.Restrictions: As expected the program gives the correct results for relativistic hydrogen-like ions with the kinetic energies up to 1 GeV/u and at the crystal thicknesses of 1–100 μm. The restrictions are: first, the program might give inadequate results, when the ion kinetic energy is too large (>10 GeV/u); second, the unaccounted physical factors may be significant at specific conditions. For example, the spontaneous emission by exited highly charged ions, as well as both energy and angular spread of the incident beam, could lead to additional broadening of the resonance. The medium polarization by the electric field of ion can influence the electronic energy levels of the ion in the non-relativistic case. The role of these factors was discussed in the references. Also, the large crystal thickness may require large computational time.Running time: In general, the running time depends on the number of processors. In our tests we used the crystal thickness up to 100 μm and the number of 2.66 GHz processors was up to 100. The running time was about 1 hour in these conditions.     

129I AMS at 0.5 MV tandem accelerator

The ¹²⁹I measurement program has been established at the 0.5 MV ‘Tandy’ accelerator of the PSI/ETH Zürich AMS facility. This development was made possible by using a SiN window instead of Mylar one in a gas ionization detector. The setting up of the ¹²⁹I measurement at Tandy is simple, the acquired performance is stable and reliable, and the quality of results is equal to or better than at our larger EN-tandem. With this setup, high sample throughput, which is required in many ¹²⁹I studies, can be easily achieved. The measurements are performed in the +3 charge state. At this charge state the major difficulty in the ¹²⁹I⁺³ identification is caused by a highly abundant 43⁺¹ (m = 43, q = +1) molecule interference. This is a positive molecular ion, because its intensity reduces exponentially with an increase in gas stripper pressure. We conclude that this molecule is ²⁷Al¹⁶O⁺ (m/q = 43/1 = 129/3) and comes from the break-up of (Al₂O₃ + Al)^? (m = 129) precursor at the terminal: (Al₂O₃ + Al)^? → ²⁷Al¹⁶O⁺. The expected isobaric interferences ⁴³Ca⁺¹ and ⁸⁶Sr⁺², which also originate from the break-up of molecules in the stripper, were found to be low and do not disturb the ¹²⁹I⁺³ measurements. The best repeatable performance with our standard sample material was achieved at 0.14 μg/cm² Ar gas stripper pressure with machine blanks showing ～6 × 10^?14 normalized ¹²⁹I/I ratio and 9% transmission through the accelerator. However, high ²⁷Al¹⁶O⁺ molecular rates were observed from the user samples, and in order to destroy these molecules we had to increase the stripper pressure to ～0.22 μg/cm². This increase in the stripper pressure degraded the machine blank values to ～9 × 10^?14 and reduced transmission to 8%. Nevertheless, the achieved measurement conditions are sufficient for measurement of nearly all ¹²⁹I samples that have been submitted to PSI/ETH over the last few years.     

Automated recordkeeping of nuclear materials at electric power plants powered with a water-moderated-water-cooled nuclear reactor

Conclusions The automated nuclear-material recordkeeping system based on the NUMIS-2 program is at present being introduced at the Novororonezh electric power plant. Concurrently, the program is being modified in order to allow its use by the computer model being created in the COMECON member-nations. In the long term, it is expected that the recordkeeping program will become a component part of a single automated control systems of individual electric power plants.The NUMIS-2 program was approved for nuclear-material recordkeeping use after it was tested on the first fuel load of the fourth unit of the Novovoronezh electric power plant. The experiment confirmed the feasibility of automating the processing and storing of nuclear-material information and of recording that information and on the standard computer carriers of information. In principle, these same records can be submitted to the national recordkeeping service (or to the International Atomic Energy Agency) for their further immediate processing by means of the computer program employed by the service. In this manner, the recordkeeping system becomes closed, which makes it promising.We note that the propesed nuclear-material recordkeeping system satisfied the basic requirements of recordkeeping by computer laid down by the International Atomic Energy Agency as well as the required order of reporting by the plants under the control of the Agency.Translated from Atomnaya Énergiya, Vol. 45, No. 4, pp. 267–270, October, 1978.     

Reflective light modulator based on epsilon-GaSe crystal

We report the results of investigating a low-voltage, polarization-insensitive, reflective-type modulator based on an epsilon-GaSe crystal and operated at the 1.960-eV line of a He-Ne laser. We demonstrate that the modulation in an Al-epsilon-GaSe-Cu device results mainly from the Franz-Keldysh effect. Relatively high speed and low operating voltage could make these modulators with Schottky-barrier contacts attractive devices in the red range of the spectrum.