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Tests for the instability resulting from temperature changes occurring during transient modes of operation of a reactor
ReactorSaence and Technology(1.N.E PansA/B). l%I. Vol. 14. pp. 67 to 6s.
ABSTRACTS
PergamOn PIUSLtd.
Rintcd in NorthernIreland
AND TITLES OF FUTURE
PAPERS
Atomnaya Energiya Vol. 9, No. 5 Use of (a,n) reactions in quantitative assays of dressing products for beryllium, boron and fluorine: 1. N. PLAKSIN, V. N. SMIRNOV and L. P. STARCHIK. A rapid method based on (a,n) reactions is described for use in assaying dressed products for Be, B, and F. The a-ray source is 250 ,I’of 210Po; the neutrons are recorded by a neutron counter. The dressed products examined in this way are fluorite and ores of boron and beryllium, or ores rich in B and F, the error of measurement being 1.5-2%. Any one element can be assayed provided that the content of any other element having a high (2.n) cross section is constant.
Replacement of a block in a two-dimensional rectangular array: L. TRLIFAY and J. Ro&K. The results are given from a study of the effects of modifying one block in an infinite uniform two-dimensional square array. The solution obtained for an inactive medium is analogous to one given elsewhere; that for a medium producing neutron multiplication is obtained by means of a modified form of a method used in the quantum theory of fields. The case of a critical infinite array is considered as the limit of the two preceding cases. The results obtained (subject to homogenization conditions) correspond to those found for the analogous homogeneous case.
Uranium monocarbide: G. A. MEERSON,R. G. KOTEL’NIKOV and S. N. BASHLYKOV. Uranium monocarbide is of interest as a material for fuel rods and for nuclear thermoelectric generators. A study of the relation of composition to synthesis conditions has resulted in a scheme for the best method of making carbide of stoichiometric composition. It is possible to make specimens of porosity about 5 % as a result of the sintering and hot-pressing studies that have been made on UC and mixtures of UC with U. The density of UC powder (pyknometer) is 12.97 & O-60 g/cm*; UC has a microhardness of 923 * 56 kg/mm?, and its thermal conductivity varies from O-028 to 0.04 cal cm-l se~-“C-~ in the range from 100 to 700°C; the mean linear expansion coefficient for the range from 20 to 15OO‘C is 11.6 x 1O-a. Specimens of UC have been cycled 500 times between 200 and IOOO’C without rupture; specimens of UC + U have withstood more than 1000 such cycles.
The increase in internal friction associated with temperature changes in uranium: Yu. N. SOKURSKII and Yu. V. BOBKOV. An internal-friction mechanism described previously for heated uranium has been used to derive a semi-quantitative estimate of the increase in internal friction as a function of the rate of heating and of the frequency and amplitude of the oscillations. The results agree satisfactorily with those found fromexperimelt. A study is made of the effects of the initial state of the material on the increase in the internal friction during the initial stages of the heating.
Tests for the instability resulting from temperature changes occurring during transient modes of operation of a reactor: R. JANE and R. DESAY. A discussion is given of the kinetics of a Calder Hall type uranium-graphite reactor; allowance is made for the temperature coefficient of reactivity and for the reactivity changes resulting from burn-up. It is found that the minimum positive period is not less than I70 set for levels of burn-up up to 3000 MW-days/ ton.
Letters to the Editor The fission cross-sections of *33Th, ‘WJ, n37Np, and z3aU for neutrons of energies ranging from 10 to 22 MeV: V. M. PANKRATOV, N. A. VLA.WVand B. V. RYBAKOV.
Isothermal irradiation of non-fissile materials in a reactor by means of calorimetric devices: N. F. PRAVDYUK, V. N. KUZNET-
Measurement of radiitive-capture cross sections for fast neutrons: Yu. YA. STAVI~~KII and V. A. TOLSTIKOV. The gamma rays produced when neutrons of energy 3 MeV are scattered ineb+ically: A. L. ANDROSENKO, D. L. BRODER and
sov and N. 1. LALETIN.
A. 1. LASHUK.
Production of thin layers of thorium, uranium, neptunium, plutonium and americium: G. 1. KHLEBNIKOV and E. P. DER-
A discussion is given of the heat generated in irradiated inactive materials by the gamma rays produced in the core of a reactor. The mass absorption coefficient is calculated as a function of Z for an RFT spectrum. A description is given of a steady-state method developed on the RFT for calculating the heat 4 released in unit mass of an inactive material irradiated within a fuel-rod assembly. The results for aluminium, steel 30, tin, and lead range from 2.2 to 3.7 W/g for cylinders 13.5 and 10 mm in diameter used in a 10 MW reactor. It is found that 4 varies as a function of the height of a channel passing through the core according to a cosine law. A method is described that has been used in isothermal irradiations of specimens and cans at temperatures in excess of the temperature of the coolant.
GUNOV.
A device for examining the effects of gamma rays on semiconductor materials: B. M. KONOVALENKO, S. M. RYVKIN, I. D. YAROSHETSKIIand L. P. Booo~~zov.
Measurement of the speed of ultd in molten alkali metals: YIJ. S. TRELIN, I. N. VtislL’ev and V. V. ROGHCHUPKIN. Radiation-induced chlorbmtion of benzene: L. A. KRASNOUSOV, P. V. ZIMAKOV and E. V. VOLKOVA.
Thermodynamics of the reduction of KF and NaF by metallic calcium and magnesium: I. M. DUBROVIN and A. K. EVSEEV. News of Science and Technology-Bibliography 67
ABSTRACTS
PergamOn PIUSLtd.
Rintcd in NorthernIreland
AND TITLES OF FUTURE
PAPERS
Atomnaya Energiya Vol. 9, No. 5 Use of (a,n) reactions in quantitative assays of dressing products for beryllium, boron and fluorine: 1. N. PLAKSIN, V. N. SMIRNOV and L. P. STARCHIK. A rapid method based on (a,n) reactions is described for use in assaying dressed products for Be, B, and F. The a-ray source is 250 ,I’of 210Po; the neutrons are recorded by a neutron counter. The dressed products examined in this way are fluorite and ores of boron and beryllium, or ores rich in B and F, the error of measurement being 1.5-2%. Any one element can be assayed provided that the content of any other element having a high (2.n) cross section is constant.
Replacement of a block in a two-dimensional rectangular array: L. TRLIFAY and J. Ro&K. The results are given from a study of the effects of modifying one block in an infinite uniform two-dimensional square array. The solution obtained for an inactive medium is analogous to one given elsewhere; that for a medium producing neutron multiplication is obtained by means of a modified form of a method used in the quantum theory of fields. The case of a critical infinite array is considered as the limit of the two preceding cases. The results obtained (subject to homogenization conditions) correspond to those found for the analogous homogeneous case.
Uranium monocarbide: G. A. MEERSON,R. G. KOTEL’NIKOV and S. N. BASHLYKOV. Uranium monocarbide is of interest as a material for fuel rods and for nuclear thermoelectric generators. A study of the relation of composition to synthesis conditions has resulted in a scheme for the best method of making carbide of stoichiometric composition. It is possible to make specimens of porosity about 5 % as a result of the sintering and hot-pressing studies that have been made on UC and mixtures of UC with U. The density of UC powder (pyknometer) is 12.97 & O-60 g/cm*; UC has a microhardness of 923 * 56 kg/mm?, and its thermal conductivity varies from O-028 to 0.04 cal cm-l se~-“C-~ in the range from 100 to 700°C; the mean linear expansion coefficient for the range from 20 to 15OO‘C is 11.6 x 1O-a. Specimens of UC have been cycled 500 times between 200 and IOOO’C without rupture; specimens of UC + U have withstood more than 1000 such cycles.
The increase in internal friction associated with temperature changes in uranium: Yu. N. SOKURSKII and Yu. V. BOBKOV. An internal-friction mechanism described previously for heated uranium has been used to derive a semi-quantitative estimate of the increase in internal friction as a function of the rate of heating and of the frequency and amplitude of the oscillations. The results agree satisfactorily with those found fromexperimelt. A study is made of the effects of the initial state of the material on the increase in the internal friction during the initial stages of the heating.
Tests for the instability resulting from temperature changes occurring during transient modes of operation of a reactor: R. JANE and R. DESAY. A discussion is given of the kinetics of a Calder Hall type uranium-graphite reactor; allowance is made for the temperature coefficient of reactivity and for the reactivity changes resulting from burn-up. It is found that the minimum positive period is not less than I70 set for levels of burn-up up to 3000 MW-days/ ton.
Letters to the Editor The fission cross-sections of *33Th, ‘WJ, n37Np, and z3aU for neutrons of energies ranging from 10 to 22 MeV: V. M. PANKRATOV, N. A. VLA.WVand B. V. RYBAKOV.
Isothermal irradiation of non-fissile materials in a reactor by means of calorimetric devices: N. F. PRAVDYUK, V. N. KUZNET-
Measurement of radiitive-capture cross sections for fast neutrons: Yu. YA. STAVI~~KII and V. A. TOLSTIKOV. The gamma rays produced when neutrons of energy 3 MeV are scattered ineb+ically: A. L. ANDROSENKO, D. L. BRODER and
sov and N. 1. LALETIN.
A. 1. LASHUK.
Production of thin layers of thorium, uranium, neptunium, plutonium and americium: G. 1. KHLEBNIKOV and E. P. DER-
A discussion is given of the heat generated in irradiated inactive materials by the gamma rays produced in the core of a reactor. The mass absorption coefficient is calculated as a function of Z for an RFT spectrum. A description is given of a steady-state method developed on the RFT for calculating the heat 4 released in unit mass of an inactive material irradiated within a fuel-rod assembly. The results for aluminium, steel 30, tin, and lead range from 2.2 to 3.7 W/g for cylinders 13.5 and 10 mm in diameter used in a 10 MW reactor. It is found that 4 varies as a function of the height of a channel passing through the core according to a cosine law. A method is described that has been used in isothermal irradiations of specimens and cans at temperatures in excess of the temperature of the coolant.
GUNOV.
A device for examining the effects of gamma rays on semiconductor materials: B. M. KONOVALENKO, S. M. RYVKIN, I. D. YAROSHETSKIIand L. P. Booo~~zov.
Measurement of the speed of ultd in molten alkali metals: YIJ. S. TRELIN, I. N. VtislL’ev and V. V. ROGHCHUPKIN. Radiation-induced chlorbmtion of benzene: L. A. KRASNOUSOV, P. V. ZIMAKOV and E. V. VOLKOVA.
Thermodynamics of the reduction of KF and NaF by metallic calcium and magnesium: I. M. DUBROVIN and A. K. EVSEEV. News of Science and Technology-Bibliography 67