Measurement of the subcriticality of power-stressed reactors with an analog reactimeter

Conclusions A technique has been developed for measuring the effects of reactivity in a subcritical reactor with an analog reactimeter. It is based on the compensation of the current applied to the reactimeter input from the neutron detector. The compensation of current produced by neutrons of the subcritical multiplying assembly formalizes the algorithm for reactivity calculation, making it an adequate model of a reactor with a source and making it possible to determine the subcriticality without prior entry into the critical state. In this case the measurements are made in the presence of neutron sources characteristic of power-stressed reactors. The regular devices of the control and safety system could be used to produce unsteady variation of the neutron flux.All of this permits the proposed method to be extended to zero-power reactors and to power-stressed reactors. Once the subcriticality has been measured an analog of the neutron source is introduced into the reactimeter. This instrument measures the effects of reactivity in the subcritical state without the reactor being previously put into the critical state, monitors the entry of the reactor into the critical state by checking the reactivity, and makes all the measurements usually made with analog reactimeters. If the intensity of the source does not change during measurements (5–10 min) when chambers sensitive to rays (e.g., KNK-56 chambers) are used as neutron-flux detectors, then the accuracy of -ray compensation does not affect the results of the measurements.Translated from Atomnaya Énergiya, Vol. 45, No. 5, pp. 375–376, November, 1978.     

Experimental study of burn-up regimes in mixtures of C2H2+O2+N2 in closed tubes

An experimental study is performed of burn-up regimes in C₂H₂+O₂+N₂ acetylene mixtures in closed volumes formed by tubes with sealed ends and sections of 50–80 cm² for various initiation methods. Conditions are determined for detonation-free burn-up, as well as for propagation of a regime intermediate between combustion and detonation.Arzamas. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 2, pp. 43–46, March–April, 1992.     

Effect of Hydroxide Calcination Temperature,Cold Isostatic Pressing (CIP) Pressure,and Sintering Temperature on Properties of ZrO2 + 3 mol.% Y2O3 Ceramic

ZrO₂ + 3 mol.% Y₂O₃ ceramic specimens are prepared by sintering, at 1500 and 1600°C, preforms molded from calcined hydroxide powders at 850 and 750°C using a cold isostatic pressing (CIP) technique. Bending strength and density measured as a function of the CIP pressure is shown to be quite different for specimens sintered at the two temperatures. Implications of this different behavior are discussed.     

Crystallization of comminuted boron powders

Conclusions An x-ray diffraction investigation has established that, irrespective of their degree of amorphization, comminuted boron powders crystallize after melting in the rhombohedral structure, i.e., revert to their original crystalline state.Translated from Poroshkovaya Metallurgiya, No. 4 (148), pp. 83–87, April, 1975.     

Experiments on the synthesis of neutron-deficient isotopes of kurchatovium in reactions with accelerated50Ti ions

Conclusions A number of conclusions can be drawn from the aggregate of experimental results.The method of synthesis of transfermium elements in the irradiation of lead isotopes with ions with mass A_I40 atomic units, investigated earlier [12] for the example of the reaction Pb(⁴⁰Ar, xn)Fm, is also extremely effective using⁵⁰Ti ions. The reactions Pb(⁴⁰Ar, 2n)Fm and Pb(⁵⁰Ti, 2n)Ku have approximately equal cross sections, which might have been expected on the basis of theoretical estimates. This permits us to hope that this method can be used successfully for the synthesis of heavier elements in the reactions induced by⁵⁴Cr,⁵⁵Mn, and⁵⁸Fe ions.In all probability, the substantial changes in the systematics of the half-lives for even-even isotopes of kurchatovium are associated with the structure of the barriers to fission of these nuclei. From this standpoint, it seems important to investigate the properties of more neutron-deficient isotopes of kurchatovium, using, in particular, the reactions with²⁰⁴Pb, and to attempt to advance into the region of elements with Z 106. On the other hand, a detailed theoretical analysis must be made of the data obtained on the basis of the modern theory of nuclear fission, which, in our opinion, will aid in a more reliable prediction of the properties of heavy and ultraheavy elements.Translated from Atomnaya Énergiya, Vol. 38, No. 6, pp. 382–390, June, 1975.     

Preparation of monolithic ZnSxSe1−x layers via chemical vapor deposition followed by hot isostatic pressing

A process is described for the preparation of monolithic ZnS_xSe_1?x (0.1 < x < 0.6) plates uniform in composition. The effect of hot isostatic pressing on the optical and structural properties of zinc sulfoselenide is examined.     

Effectiveness of dispersing the blow to speed up the steelmaking operation

Various methods of injecting steelmaking baths with oxidizing and neutral gases through the bottom of hearth-type furnaces have come into wider use abroad in recent years. Having decided that potential problems with the durability of the lances would preclude the injection of oxygen through the bottom of its arc steelmaking furnaces, the Moldavian Metallurgical Plant (MMZ) decided to install lances in the side of the furnace and inject oxygen deep into the bath. The gas-oxygen lances were installed in the shell of the furnace 300–500 mm below the surface of the bath. Placing the cermet lances in the shell satisfies operating requirments, makes it easier to service the lances, and allows them to be repaired or replaced in the working regime. The requirements that must be met for high-rate steel production are best satisfied with the use of refractories made by the company RHI AG. Results obtained in the course of the above-mentioned project were used to construct an algorithm that optimizes the relationship between the depth of immersion of the lance in the melt and the direction of the lance relative to the surface of the bottom of the furnace. Innovations such as these, developed by the MMZ in collaboration with the company TECHCOM Import Export to intensify steelmaking operations, are now in use on the arc furnaces at the MMZ’s ISTIL plant.