Physical Startup Research Articles

Tokamak T-15MD—Two years before the physical start-up

At the present time, in the NRC Kurchatov Institute under the auspices of the Federal Target Program “Nuclear energy-technologies of new generation for period 2010–2015 and to the prospect until 2020” the tokamak T-15MD and supporting facilities are being built. The preassembly of the tokamak T-15MD magnet system together with the vacuum vessel was completed at a plant in Bryansk. All elements of the magnet system and vacuum vessel have been delivered to the NRC “Kurchatov Institute” in Moscow for the tokamak T-15MD assembly. It is expected that the T-15MD assembly will be completed in March of 2019. The reconstruction of the sub-station 110/10/04 kV for own needs was completed in 2017 and the reconstruction of the main sub-station 110/10/1 kV, 300 MW was completed in 2018. Twenty- two of the new transformers 10/1 kV and 20 new thyristor convertors will be installed during 2018–2019 period. One gyrotron with output power 1 MW for pre-ionization should be installed in 2019. Tokamak T-15MD connection to water and electrical communication and also the adjustment of control system will be completed in the middle of 2020. Physical start-up T-15MD is scheduled for December 2020 year.

COMPARISON OF NEUTRON SPECTRUM IN THE WWR-K REACTOR WITH LEU FUEL AGAINST HEU ONE

WWR-K is the research tank-type light-water heterogeneous reactor. Reactor operation started in 1967 with enrichment36 % in uranium-235. In 2016 reactor conversion to low-enriched uranium fuel (19.7 % in uranium-235) was implemented with the VVR-KN-type fuel assemblies (FA). In view of reactor operation, compact configuration of the core was chosen, where, following fuel burning up, side water reflector is gradually changed by beryllium one. Besides, an amount of work elements of the reactor control and protection system is increased in the new reactor core. Following results of measurement of the thermal neutron flux density, carried out in the core center in course of reactor physical startup, it has increased up to 2·1014 cm-2s-1. Thus, in terms of experimental capacities, reactor has gained after conversion in attractiveness. As is known, uranium fission is accompanied by generation of neutrons, which energies obey the Watt’s spectrum, that is, the spectrum peak is associated with the neutrons having the energy 0.7 MeV, whereas the neutron average energy comprises 2 MeV. Due to an enhanced amount of uranium-238 in the new low-enriched uranium fuel FA, neutron spectrum is making «harder». In the presented paper, neutron spectra in the core irradiation channels of re calculated by means of the computer code MCNP, and comparison of neutron spectra in the WWR-K reactor core with high-enriched uranium fuel against lowenriched fuel is conducted.

Physical Start-Up of the Power Supply System for Corrector Magnets of the European XFEL

The European X-ray Free-Electron Laser (XFEL) was commissioned in 2017. Budker Institute of Nuclear Physics (BINP) participated in the development, production and delivery of the power system for the corrector magnets. Seven types of high-precision power supplies (current sources) to feed the corrector magnets were developed. To ensure high reliability, a “hot-swap” system was developed for the power supplies. About 400 power supplies for the corrector magnets and 50 hot-swap devices have been put into operation. This article presents details of starting up the power system.

CALCULATED STUDY OF NEUTRONIC CHARACTERISTICS OF EXPERIMENTAL DEVICES

The article presents calculated study of the neutronic characteristics of the experimental device (ED) designed to simulate the residual energy release in the melt trap due to neutron irradiation [1]. The relations of energy release in the melt in different variants of traps filling to the energy release in the reactor are estimated. Proposals for optimal physical start-up have been developed.

Simulation of VVER-1000 startup physics tests using the MCU Monte Carlo code

The main objective of this work is to make the quality test and verification of a full-scale computer model of the VVER-1000 reactor with the detailed description of the geometry and material composition. Using the computer model and MCU Monte Carlo code, we simulated the experiments conducted at the stage of physical start-up of the third power unit of Rostov NPP (Russia) in December 2014. The following neutron-physical characteristics were calculated: effective neutron multiplication factor, critical boric acid concentration, efficiency of single control rod cluster, integral and differential efficiency of control rod group, scram system reactivity worth, and reactivity coefficients. The calculated neutron-physical characteristics were compared with the measured ones. The comparison shows agreement with the measured data over the range of the experimental error and statistical uncertainty of the calculation. To reduce the impact of statistical uncertainty on the calculated differential control rod reactivity worth and reactivity coefficients we applied a special approach for the estimation of these parameters.

Numerical Simulation of Measurements during the Reactor Physical Startup at Unit 3 of Rostov NPP

The results of numerical calculations and measurements of some reactor parameters during the physical startup tests at unit 3 of Rostov NPP are presented. The following parameters are considered: the critical boron acid concentration and the currents from ionization chambers (IC) during the scram system efficiency evaluation. The scram system efficiency was determined using the inverse point kinetics equation with the measured and simulated IC currents. The results of steady-state calculations of relative power distribution and efficiency of the scram system and separate groups of control rods of the control and protection system are also presented. The calculations are performed using several codes, including precision ones.

К ВОПРОСУ О ЗАПАЗДЫВАЮЩИХ НЕЙТРОНАХ В РЕАКТОРАХ С УРАНОВЫМ ЯДЕРНЫМ ТОПЛИВОМ

К ВОПРОСУ О ЗАПАЗДЫВАЮЩИХ НЕЙТРОНАХ В РЕАКТОРАХ С УРАНОВЫМ ЯДЕРНЫМ ТОПЛИВОМ

Physical startup tests for VVER-1200 of Novovoronezh NPP: advanced technique and some results

Abstract The intention of the startup physics tests was to confirm design characteristics of the core loading and their compliance with safety analysis preconditions. The program of startup tests for the leading unit is usually composed in such a way that is is possible to study as much neutron-physical characteristics as possible in the safest condition of zero power. State-of-the-art safety analysis is including computer codes that use three dimensional neutron kinetics and thermohydraulics models. For the substantiation of such models, for its validation and verification there is a need in reactor experiments that implementing spatially distributed transients. We based on such statements when composing hot zero power physical startup program for the new VVER-1200 unit of Novovoronezh NPP. Several tests unconventional for VVER were developed for that program. It includes measuring the worth for each of control rod groups and measuring of single rod worth from the inserted groups – test that models rod ejection event in some sense.

Experimental study of asymmetric boron dilution at VVER-1000 of Kudankulam NPP and its simulation

Abstract The Kudankulam NPP units contain additional and unique for VVER Quick Boron Injection System (QBIS) for beyond-design-basis accident management without scram. During the physical start-up stage at hot zero power of both Kudankulam units, special tests were performed to assess the efficiency of the system. In the course of test three out of four QBIS tanks had been promptly opened and it led to the asymmetrical injection of boric acid into the core. The scenario of the tests may address to the inhomogeneous boron dilution process that is now an essential part of safety analysis of pressurised water reactors. The simulation of the process, including ex-core ion chambers readings, has been accomplished using ATHLET/BIPR-VVER code. Behaviour of some reactor parameters in the course of the test and some results of the simulation are discussing in the paper. Authors believe the process of the asymmetrical injection of boric acid may be useful for verification and validation of coupled neutronic and thermo-hydraulic codes widely used for safety analysis, including analysis of boron dilution accident.

IVV-2M Nuclear Research Reactor

Physical startup of the IVV-2 nuclear research reactor at nominal power 5 MW was conducted 50 years ago. Designers, builders, and personnel at the Institute of Reactor Materials needed about 10 years to develop a new reactor – IVV-2M – on the basis of the IVV-2 design. The redesign, which was accomplished in 1974–1982, made it possible not only to increase the neutron-physical parameters of the reactor but also the nuclear and radiation safety. The structural features of the IVV-2M reactor and the basic problems now being solved as well as the prospects for new advancement are shown in the present article.

Estimation of experimental uncertainty for physical measurements based on the start-up data of the latest VVER-1000 units

Abstract During the last decades several new VVER-1000 units of different projects have been commissioned. At some of them similar initial fuel loadings were implemented. To determine experimentally neutron-physics characteristics of those units almost similar physical start-up test programs were performed and measurement equipment were also similar. The paper presents the analysis of some result of neutron-physics characteristics that were carried out during physics start-up of VVER-1000 units with similar initial fuel loading. The subject of analysis is an estimation of experimental uncertainties. An effort is made to consider individual test result as a single random realization of universal set. It is assumed the analysis of individual results spread helps to estimate general inherent uncertainty of experiment.

Simulative verification of a novel semi-active broadband energy harvester

Abstract. This paper presents a semi-active broadband vibrational-energy harvesting system. Based on a non-resonant rotational generator, electronic circuitry was used to overcome the physical start-up restrictions. Due to the functional design it remains an energy harvester suitable for battery-less devices. For the first time a vibrational energy harvester is presented that allows standardization and thus higher volume production. A system layout, simulation, and measurement data will be shown.

Application of controlled startup to increase the safety of ship pressurized water nuclear reactors

The operating results for antimony-beryllium neutron startup sources in the reactor core of the Vaigach icebreaker are presented. It is shown that such sources used together with pulsed startup apparatus secure controlled startup of ship pressurized water reactors during operation from the initial subcritical state over a period of ≥200 days after shutdown. It is also shown that the neutron-physical state of the reactors can be monitored during loading of the fuel assemblies and physical startup.

Comparison between the measured and calculated reactivity in measuring the effectiveness of the emergency protection at the stage of physical start-up of unit no. 3 at the Kalinin nuclear power plant

This paper presents comparisons between the effectiveness of the emergency protection under both stationary and nonstationary formulations calculated with the use of the RADUGA-7.5 package [1] and experimental data obtained in measuring the “weight” of the emergency protection in the process of physical start-up of the VVER-1000 reactor of unit no. 3 of the Kalinin NPP. On the basis of the results obtained, recommendations are given on comparing the measured and calculated reactivity and parameters determined by using its value.

A new method for improving critical extrapolation

The divergent phenomenon of critical extrapolation and ρ–1/N extrapolation curve is analyzed during the physical startup of a reactor. Aiming at the deficiency of the existing improving method—constant neutron source elimination (CNSE) method, a new method—variable neutron source elimination (VNSE) is proposed. This new method aims at getting accurate neutron count rate for extrapolation, and considers all the errors caused by the neutron source leakage, reactor spatial effect and neutron detector positions as a whole. Applied to a small reactor, this VNSE method can remove all errors and eliminate the divergence of extrapolation so that the accurate ρ–1/N extrapolation curve is got. The VNSE method is efficient and accurate for the critical extrapolation.

Calculation of reactivities using ionization chamber currents with different sets of kinetic parameters for reduced scram system efficiency in the VVER-1000 of the third unit of the Kalinin nuclear power plant at the stage of physical start-up

The effectiveness of the VVER-1000 reactor scram system is analyzed using ionization chamber currents with different sets of kinetic parameters with allowance for the isotopic composition in the calculation of these parameters. The most “correct, aesthetically acceptable” results are obtained using the eight-group constants of the ROSFOND (BNAB-RF) library. The difference between the maximum and minimum values of the scram system effectiveness calculated with different sets of kinetic parameters slightly exceeds 2β. The problems of introducing corrections due to spatial effects are not considered in this study.

Reactivity effects in VVER-1000 of the third unit of the kalinin nuclear power plant at physical start-up. Computations in ShIPR intellectual code system with library of two-group cross sections generated by UNK code

The ShIPR intellectual code system for mathematical simulation of nuclear reactors includes a set of computing modules implementing the preparation of macro cross sections on the basis of the two-group library of neutron-physics cross sections obtained for the SKETCH-N nodal code. This library is created by using the UNK code for 3D diffusion computation of first VVER-1000 fuel loadings. Computation of neutron fields in the ShIPR system is performed using the DP3 code in the two-group diffusion approximation in 3D triangular geometry. The efficiency of all groups of control rods for the first fuel loading of the third unit of the Kalinin Nuclear Power Plant is computed. The temperature, barometric, and density effects of reactivity as well as the reactivity coefficient due to the concentration of boric acid in the reactor were computed additionally. Results of computations are compared with the experiment.

Main stages of physical startup of BN-600 and comparison of the measured and nominal characteristics

A retrospective exposition of the preparation for and performance of the physical startup of BN-600 is presented. There are three sections: program of physical startup and measurements of the physical characteristics, physical startup procedure, and main results of the investigations of the neutron-physical characteristics of a reactor and their comparison with the nominal characteristics. The use of the experience gained in performing the physical startup of BN-600 will be important for the startup of other advanced fast reactors, first and foremost, BN-800.

Physical start-up of the first stage of IREN facility

The full-scale scientific research complex IREN will comprise a 200-MeV linear accelerator LUE-200 with a beam power about 10 kW, a subcritical multiplying target, and beam infrastructure with experimental pavilions, as well as technological, control, safety and service systems. The characteristics of the full-scale complex IREN (integral neutron yield 1015n/s and pulse width 0.6 μs) will allow it to rank among the best neutron sources of such class GELINA (Belgium) and ORELA (USA). The realization of the project is conducted in several stages. The first stage includes the construction of the LUE-200 linear accelerator and nonmultiplying target. This will make possible to carry out experiments which require precision neutron spectroscopy in the energy range from fractions of eV to hundreds of eV already at the first stage of IREN. The results of the physical start-up of the first stage of IREN facility at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research are presented. General scheme and current status of the electron linac are described. Achieved parameters are: pulsed electron beam current – 2.0 A; electron energy – 30 MeV; pulse width – 100 ns; repetition rate – 25 Hz; integral neutron yield (3÷5)•1010 n/s.

Physical startup of energy dispersive EXAFS spectrometer at Kurchatov Center of synchrotron radiation and nanotechnologies

The energy dispersive EXAFS spectrometer was created by a joint effort of the Joint Institute for Nuclear Research, Belarus State University, the Kurchatov Institute Russian Research Center, and the Institute of Crystallography of the Russian Academy of Sciences. A brief description of the spectrometer is given. The first results of a complex adjustment of the spectrometer units on the synchrotron radiation beam are presented.