THE OCCURRENCE OF (n, 3n) REACTIONS IN A NUCLEAR REACTOR

1959 ◽  
Vol 37 (7) ◽  
pp. 815-826 ◽  
Author(s):  
T. A. Eastwood ◽  
J. C. Roy
Keyword(s):  
Thermal Neutron ◽  
Compound Nucleus ◽  
Target Nucleus ◽  
Nuclear Reactor ◽  
Neutron Reactor ◽  
Neutron Evaporation ◽  
Competing Reactions

The reactions Bi209(n, 3n)Bi207 and Au197(n, 3n)Au195 have been observed to occur in NRX, a thermal neutron reactor. Competing reactions leading from Bi209 or Au197 to the same products have been shown to be negligible. Within the uncertainties of the methods used the yields of Bi207 and Au195 are about those expected on the basis of neutron evaporation from the compound nucleus formed by the amalgamation of the incoming neutron and the target nucleus.

scholarly journals Modeling and control of xenon oscillations in thermal neutron reactors

2020 ◽  
Vol 6 ◽  
pp. 48
Author(s):  
Bertrand Mercier ◽  
Zeng Ziliang ◽  
Chen Liyi ◽  
Shao Nuoya
Keyword(s):  
Thermal Neutron ◽  
Doppler Effect ◽  
Nuclear Reactor ◽  
Numerical Models ◽  
Fast Neutrons ◽  
Control Law ◽  
Group Model ◽  
Modeling And Control ◽  
The Doppler Effect ◽  
Sensitive Parameters

We study axial core oscillations due to xenon poisoning in thermal neutron nuclear reactors with simple 1D models: a linear one-group model, a linear two-group model, and a non-linear model taking the Doppler effect into account. Even though nuclear reactor operators have some 3D computer codes to simulate such phenomena, we think that simple models are useful to identify the sensitive parameters, and study the efficiency of basic control laws. Our results are that, for the one-group model, if we denote the migration area by M 2 and by H the height of the core, the sensitive parameter is H/M. H being fixed, for the 2 groups model, there are still 2 sensitive parameters, the first one being replaced by M12+M22 where M12 denotes the migration area for fast neutrons and M22 the migration area for thermal neutrons. We show that the Doppler effect reduces the instability of xenon oscillations in a significant way. Finally, we show that some proportional/integral/derivative (PID) feedback control law can damp out xenon oscillations in a similar way to the well-known Shimazu control law [Y. Shimazu, Continuous guidance procedure for xenon oscillation control, J. Nucl. Sci. Technol. 32, 1159 (1995)]. The numerical models described in our paper have been applied to PWR.

Thermal neutron capture γ-ray spectrum of molybdenum and ruthenium

1991 ◽  
Vol 69 (6) ◽  
pp. 658-664 ◽  
Author(s):  
M. A. Islam ◽  
T. J. Kennett ◽  
W. V. Prestwich
Keyword(s):  
Thermal Neutron ◽  
Neutron Capture ◽  
Nuclear Reactor ◽  
Thermal Neutron Capture ◽  
Global Average ◽  
Transition Level ◽  
Γ Rays ◽  
Γ Ray ◽  
Strength Functions ◽  
Mcmaster University

The thermal neutron capture γ rays from natural molybdenum and ruthenium have been studied using a pair spectrometer and the tangential facility at the McMaster University Nuclear Reactor. Precise transition, level, and neutron separation energies of different isotopes are inferred. The separation energies are: Sn(93Mo) = 8069.76 ± 0.09, Sn(95Mo) = 7369.10 ± 0.10, Sn(96Mo) = 9154.31 ± 0.05, Sn(97Mo) = 6821.15 ± 0.25, Sn(98Mo) = 8642.55 ± 0.07, Sn(99Mo) = 5925.42 ± 0.15, Sn(100Ru) = 9673.48 ± 0.05, and Sn(102Ru) = 9219.64 ± 0.05 keV. The M1 strength functions of 100Ru,102Ru, 96Mo, and 98Mo are (34 ± 15) × 10−9, (82 ± 41) × 10−9, (22 ± 7) × 10−9, and (25 ± 8) × 10−9 MeV−3, respectively. All values but that for 102Ru agree with the global average of (20 ± 6) × 10−9 MeV−3. The average [Formula: see text] of 96Mo observed is 247 ± 175 e2 fm4 MeV−1.

scholarly journals Fast Neutron Cross Sections in the 2S–1D Shell

1972 ◽  
Vol 50 (20) ◽  
pp. 2385-2390 ◽  
Author(s):  
G. R. Norman ◽  
W. V. Prestwich ◽  
T. J. Kennett
Keyword(s):  
Fast Neutron ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Nuclear Reactor ◽  
Low Energy ◽  
Fast Neutron Flux ◽  
Energy Data ◽  
Nucleus Formation ◽  
Compound Nucleus Formation ◽  
Neutron Cross Sections

Total neutron cross sections for six elements in the 2S–1D shell have been measured in the energy region 0.8–3.0 MeV using a new method. The experiment utilizes the fast neutron flux from a nuclear reactor with the neutron energies being determined by a measurement of their time of flight.From the present results the resonance parameters for aluminum have been determined and examined in the context of earlier low energy results for this element. The observed widths, which range to greater than 100 keV, are found to be consistent with compound nucleus formation when the reduced widths are compared with the corresponding low energy data. It is concluded that the observation of resonances with large widths is not sufficient to discount compound nucleus formation.

scholarly journals ISOSPIN DEPENDENCE OF REACTIONS 48Ca+243-251Bk

2008 ◽  
Vol 17 (supp01) ◽  
pp. 66-79 ◽  
Author(s):  
CAIWAN SHEN ◽  
YASUHISA ABE ◽  
DAVID BOILLEY ◽  
GRIGORY KOSENKO ◽  
ENGUANG ZHAO
Keyword(s):  
Compound Nucleus ◽  
Cross Sections ◽  
Coulomb Barrier ◽  
Fusion Process ◽  
Evaporation Model ◽  
Formation Stage ◽  
Step Model ◽  
Isospin Dependence ◽  
Two Stages ◽  
Neutron Evaporation

The fusion process of 48 Ca induced reactions is studied with the two-step model. In this model, the fusion process is devided into two stages: first, the sticking stage where projectile and target come to the touching point over the Coulomb barrier from infinite distance, and second, the formation stage where the di-nucleus formed with projectile and target evolve to form the spherical compound nucleus from the touching point. By the use of the statistical evaporation model, the residue cross sections for different neutron evaporation channels are analyzed. From the results, optimum reactions are given to synthesize Z=117 element with 48 Ca induced reactions.

A Review of Ntd-Induced Defects in Silicon

1980 ◽  
Vol 2 ◽  
Author(s):  
J. M. Meese
Keyword(s):  
Thermal Neutron ◽  
Nuclear Reactor ◽  
Phosphorus Doping ◽  
Float Zone ◽  
Neutron Transmutation Doping ◽  
Thermal Neutron Irradiation ◽  
Transmutation Doping ◽  
Neutron Transmutation ◽  
Induced Defects ◽  
Present Understanding

ABSTRACTNeutron transmutation doping (NTD) has become the preferred method of phosphorus doping of float zone silicon for the Si power device industry. This doping process is accomplished by thermal neutron irradiation in a nuclear reactor. One of the stable isotopes, 30Si, is transmuted to the desired dopant, 31p, by thermal neutron capture and beta decay. This transmuted product becomes electrically active only after suitable annealing of the accompanying radiation damage which is the result of a number of different displacement mechanisms. This paper will present a review of our present understanding of the production and annealing of these displacement defects.

PRODUCTION OF HEAVY ELEMENTS BY TRANSFER OF MASSIVE CLUSTERS

1992 ◽  
Vol 01 (02) ◽  
pp. 221-247 ◽  
Author(s):  
M. T. MAGDA ◽  
J. D. LEYBA
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Target Nucleus ◽  
Heavy Elements ◽  
Transfer Reactions ◽  
Isotopic Distribution ◽  
Neutron Evaporation ◽  
Massive Clusters ◽  
Multinucleon Transfer Reactions ◽  
Good Agreement

A review of various models of multinucleon transfer reactions leading to heavy elements is given. A mechanism is proposed to describe these reactions based on the assumption that massive clusters are separated from the projectile and captured as a whole by the target nucleus. The modification of the primary isotopic distribution by fission and neutron evaporation is considered. Calculated isotopic distributions and cross sections are in good agreement with experimental data for the production of Z = 96–103 elements. Predictions of the model are used to explore the possibilities of producing transfermium elements by transfer reactions.

The control of a thermal neutron reactor

1953 ◽  
Vol 1953 (3) ◽  
pp. 121-122 ◽  
Author(s):  
R.V. Moore
Keyword(s):  
Thermal Neutron ◽  
Neutron Reactor
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