NEUTRON CONSTANTS AND
PARAMETERS
INVESTIGATION OF THE 93Nb NEUTRON
CROSS-SECTIONS IN RESONANCE ENERGY RANGE
Yu.V.Grigoriev, V.Ya.Kitaev, B.V. Zhuravlev,
V.V.Sinitsa
Institute of Physics and Power Engineering,
Obninsk, Russia
S.B.Borzakov,H.Faikov-Stanchik, G.Ilchev,
Zh.V.Mezentseva , Ts.Ts.Panteleev
Frank Laboratory of Neutron Physics, JINR,
Dubna, Russia
G.N.Kim
University of Science and Technology, PAL,
Pohang, Korea
The results of gamma-ray multiplicity spectra and
transmission measurements for 93Nb in energy range
21.5 eV-100 keV are presented. Gamma spectra from 1 to 7 multiplicity
were measured on the 501 m and 121 m flight paths of the IBR-30 using
a 16-section scintillation detector with a NaI(Tl) crystals of a total
volume of 36l and a 16-section liquid scintillation detector of a
total volume of 80l for metallic samples of 50, 80 mm in diameter
and 1, 1.5mm thickness with 100% 93Nb. Besides, the total
and scattering cross-section of 93Nb were measured by means
batteries of B-10 and He-3 counters on the 124 m, 504 m and 1006 m
flight paths of the IBR-30. Spectra of multiplicity distribution were
obtained for resolved resonances in the energy region E=30-6000 eV and
for energy groups in the energy region E=21.5 eV-100 keV. They were
used for determination of the average multiplicity, resonance
parameters and capture cross-section in energy groups and for low
resonance's of 93Nb. Standard capture cross-sections of
238U and experimental gamma-ray multi-plicity spectra also
were used for determination of capture cross-section 93Nb
in energy groups. Similar values were calculated using the ENDF/B-6
and JENDL-3 evaluated data libraries with the help of the GRUCON
computer program. Within the limits of experimental errors there is
observed an agreement be-tween the experiment and calculation, but in
some groups the experimental values differ from the calculated ones.
(in English)
THE LIBRARY OF NEUTRON DATA TENDL AND
38 GROUP NEUTRON CONSTANT SYSTEM TEND1038.
S.N. Abramovich, V.P. Gorelov, A.A. Gorshikhin,
A.N. Grebennikov, V.I. Iljin, N.A. Krutjko, G.G. Pharaphontov
VNIIEF, Sarov, Russia
The library contents neutron data for 103 nuclei
- that is for 38 nuclei-actinides (from 232Th until 249Cm),
for 26 fission fragments-nuclei, for 39 nuclei of construction and
technology materials. The 38 group constants were obtained from
TENDL. High energy group boundary is 20 MeV. The energy range lower
1.2 eV contents 11 groups. The temperature and resonanse effects
were accounted. The delayed neutron parameters for 6 groups were
obtained and also yields of 40 fission fragments (light and heavy,
stable and nonstable). The fast neutron features of spherical
critical assemblies were calculated on the basis constants from TEND1038.
(in Russian)
RESOLVED RESONANCE PARAMETERS OF 236Np.
G.B. Morogovsiy, L.A. Bakhanovich.
Belarussian Academy of Sciences Institute of
Radiation Physics and Chemistry Problems, Belorussia
The multilevel Breight-Wigner parameters have been
obtained for the representation of fission cross section in the energy
region 0.01-33 eV as the result of the evaluation of 236Np
experimental fission cross section in the resolved resonance region.
(in Russian)
THE EVALUATION OF THRESHOLD REACTION CROSS
SECTIONS LEADING TO LONGLIVED RADIOACTIVE NUCLIDE PRODUCTION AT
IRRADIATION OF STEALS BY NEUTRONS OF THERMONCLEAR SPECTRUM.
A.I. Blokhin, N.N. Buleeva, V.N. Manokhin,
M.V.Mikhajlyukova, S.M. Nasyrova, M.V. Skripova
Institute of Physics and Power Engineering,
Obninsk, Russia
The present work is devoted to analysis and
evaluation of threshold reaction cross sections leading to production
of long-lived radioactive nuclides at irradiation of steals,
containing V, Ti, Cr, Fe and Ni, by neutrons of thermonuclear spectra.
On the basis of empirical systematics new evaluation of the (n,2n),
(n,p), (n,np), (n,a)
and (n,na) excitation
functions was made for all isotopes of V, Ti, Cr, Fe and Ni and
intermediate isotopes produced in the chain from irradiated isotopes
up to production of long-lived radionuclides 39Ar,
42Ar, 41Ca, 53Mn, 60Fe,
60Co, 59Ni, 63Ni. A comparison with
the experimental and other evaluated data is presented.
(in Russian)
THE RELATIVE 8-GROUP DELAYED NEUTRON ABUNDANCES
FOR MONOENERGETIC NEUTRON INDUCED FISSION OF 239Pu.
V.M. Pisaikin, L.E. Kazakov, S.G. Isaev,
G.G. Korolyov, V.A. Roschenko, R.G. Tertychnyj.
Institute of Physics and Power Engineering,
Obninsk, Russia
The energy dependence of relative abundance of
delayed neutrons in frame of 8-group model representation was obtained
for monoenergetic neutron induced fission of 239Pu.
Comparison of the present data was made with available experimental
data by other authors in terms of the average half-life of delayed
neutron precursors.
(in Russian)
THE RELATIVE 8-GROUP DELAYED NEUTRON ABUNDANCES
FOR EPITHERMAL NEUTRON INDUCED FISSION OF 235U AND 239Pu.
V.M. Pisaikin, L.E. Kazakov, S.G. Isaev,
G.G. Korolyov, V.A. Roschenko, R.G. Tertychnyj.
Institute of Physics and Power Engineering,
Obninsk, Russia
In frame of 8-group delayed neutron representation
the relative abundances of delayed neutrons for thermal neutron
induced fission of 235U and 239Pu were obtained.
Comparison of the present data was made with the ENDF/B-VI data in
the terms of average half-life of delayed neutron precursors and on
the basis of the dependence of reactivity on asymptotic period.
(in Russian)
DELAYED NEUTRON YIELD FROM FAST NEUTRON
INDUCED FISSION OF 238U
V.M. Piksaikin, L.E. Kazakov, S.G. Isaev,
V.A. Roshchenko, A.A. Goverdovski, R.G. Tertytchnyi
Institute of Physics and Power Engineering,
Obninsk, Russia
The measurements of the total delayed neutron yield
from fast neutron induced fission of 238U were made. The
experimental method based on the periodic irradiation of the
fissionable sample by neu-trons from a suitable nuclear reaction had
been employed. The preliminary results on the energy de-pendence of
the total delayed neutron yield from fission of 238U are
obtained. According to the com-parison of experimental data with our
prediction based on correlation properties of delayed neutron
characteristics, it is concluded that the value of the total delayed
neutron yield near the threshold of (n,f) reaction is not a constant.
(in English)
DELAYED NEUTRONS AS A PROBE OF NUCLEAR CHARGE
DISTRIBUTION IN FISSION OF HEAVY NUCLEI BY NEUTRONS
S.G. Isaev, V.M. Piksaikin, L.E. Kazakov,
V.A. Roshchenko.
Institute of Physics and Power Engineering,
Obninsk, Russia
A method of the determination of cumulative yields
of delayed neutron precursors is developed. This method is based on
the iterative least-square procedure applied to delayed neutron decay
curves measured after irradiation of 235U sample by thermal
neutrons. Obtained cumulative yields in turns were used for deriving
the values of the most probable charge in low-energy fission of the
above-mentioned nucleus.
(in English)
THE ENERGY SPECTRUM OF DELAYED NEUTRONS FROM
THERMAL NEUTRON INDUCED FISSION OF 235U AND ITS
ANALYTICAL APPROXIMATION
A.Yu. Doroshenko, V.M. Piksaikin, M.Z. Tarasko.
Institute of Physics and Power Engineering,
Obninsk, Russia
The energy spectrum of the delayed neutrons is the
poorest known of all input data required in the calculation of the
effective delayed neutron fractions. In addition to delayed neutron
spectra based on the aggregate spectrum measurements there are two
different approaches for deriving the delayed neutron energy spectra.
Both of them are based on the data related to the delayed neutron
spectra from individual precursors of delayed neutrons. In present work
these two different data sets were compared with the help of an
approximation by gamma-function. The choice of this approximation
function instead of the Maxwellian or evaporation type of distribution
is substantiated.
(in English)
ABOUT THE NEW POSSIBILITY FOR IMPROVEMENT OF
CALCULATION ACCURACY OF CASCADE g
-RAY DISINTEGRATION PROCESS PARAMETERS FOR HEAVY NUCLEI
A.M. Sukhovoj, V. A. Khitrov
Joint Institute for Nuclear Research, Dubna,
Russia
E.P. Grigorjev
Institute of Physics, St.-Petersburg Univercity,
St.-Petersburg, Russia
The level density and radiative strength functions
providing accurate reproduction of the experimental intensity of the
two-step cascades after the thermal neutron capture and total radiative
widths of the compound states were applied to calculate the
total g-ray spectra from
the (n,g) reaction.
Analysis showed in some cases considerable improvement of correspondence
with the experiment and allowed one to determine possible directions in
which these parameters need to be corrected for further improvement of
accuracy in calculation of the cascade
g-decay of heavy nuclei.
(in Russian)
THE CONSTANTS AND PARAMETERS OF NUCLEAR STRUCTURE AND NUCLEAR REACTIONS
HALF-LIVES OF RADIONUCLIDES USED IN NUCLEAR
GEOCHRONOLOGY AND COSMOCHRONOLOGY (EVALUATED DATA).
V.P. Chechev.
The V.G. Khlopin Radium Institute Research and
Production Association (RI RPA), Saint Petersburg
The evaluated values of half-lives of radionuclides
26Al, 40K, 53Mn, 60Fe,
87Rb, 93Zr, 98Tc, 107Pd,
129I, 135Cs, 146Sm, 176Lu,
182Hf, 187Re, 205Pb, 232Th,
235U, 238U, 244Pu, 247Cm are
presented. They are obtained from an analysis of published information
up to 2001. These half-lives are used in geochronology and cosmochronology
for determination of different radiometric ages in the history of the
Earth? Solar system and Galaxy.
(in Russian)
TEST CALCULATIONS OF PHOTONEUTRONS EMISSION
FROM SURFACE OF URANIUM SPHERE IRRADIATED BY 28 MeV ELECTRONS
A.I. Blokhin, I.I. Degtyarev.
Institute of Physics and Power
Engineering (IPPE), Obninsk, Russia
Institute for High Energy Physics, Protvino, Russia
In this paper are reported the results of physical
verification for the BOFOD photonuclear data files available for the
uranium isotopes U235, U238. These results were
compared with calculated data by the parameterization driven model of
photonuclear reaction and experimental data. Experimental data of
photoneutron yields from surface of uranium sphere irradiated by
28 MeV electrons are used for a verification. Both calculations have
been carried out with the RTS&T general purpose Monte Carlo code to
detailed electron-photon-nucleon transport simulation using the
ENDF/B-VI and EPDL evaluated data libraries.
(in English)
CALCULATIONAL ESTIMATIONS OF NEUTRON YIELD
FROM ADS TARGET
I.I. Degtyarev, O.A. Liashenko, I.A.Yazynin.
Institute for High Energy Physics, 142284
Protvino, Russia
V.I. Belyakov-Bodin.
Institute of Theoretical and Experimental
Physics, 117259 Moscow, Russia
A.I. Blokhin.
Institute of Physics and Power Engineering,
249020 Obninsk, Russia
Results of computational studies of high power
spallation thick ADS (Accelerator-Driven System) targets with
0.8-1.2 GeV proton beams are given. Comparisons of experiments and
calculations of double differential and integral n/p yield are also
described.
(in English)
NUCLEAR REACTOR DATA
BASIC FOR LOW-ACTIVATION LEAD COOLANT WITH
ISOTOPICALLY ENRICHED FOR ADVANCED NUCLEAR POWER DEVICES.
G.L. Khorasanov, A.I. Blokhin.
Russian Federal Research Center - Institute of
Physics & Power Engineering, Obninsk, Russia
The purpose of paper is in studing perspectives of
new coolants for fast reactors (FR) and accelerator driven systems (ADS).
The main concern is for their improvement using an isotopic tailoring
technique to reduce post irradiation activity. Calculation using the
FISPACT-3 code shows that 30 years irradiation of natural lead (Pb-nat),
leads to accumulation of long-lived toxic radionuclides, Bi-207, Bi-208,
and Pb-210, that extends the cooling time of activity to the clearance
level. For using lead isotope, Pb-206, instead of Pb-nat it is possible
to shorten this time. In this case, the concentration of the most toxic
polonium isotope, Po-210, essentially decreases. Calculation for lead
activation in the hard proton-neutron ADS spectrum was performed using
CASCADE/SNT code. Time dependent activity of Bi-207 produced in Pb-nat
and Pb-206 after irradiation during one year with a proton beam having
energy 0.8 GeV and current 30 mA is given. Activity of Bi-207 is
decreased by 4 orders of magnitude in going from natural lead to lead
isotope, Pb-206, as a coolant for ADS targets. In this case production
of such radiotoxic nuclide as Po-210 is also essentially diminished.
(in Russian)
