scholarly journals Improving Nuclear Safety of Fast Reactors by Slowing Down Fission Chain Reaction

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
G. G. Kulikov ◽  
A. N. Shmelev ◽  
V. A. Apse
Keyword(s):  
Cross Sections ◽  
Fast Reactor ◽  
Reactor Core ◽  
Large Contribution ◽  
Delayed Neutrons ◽  
Slowing Down ◽  
Radiogenic Lead ◽  
Radiative Neutron ◽  
Long Lifetime ◽  
Radiative Neutron Capture

Light materials with small atomic mass (light or heavy water, graphite, and so on) are usually used as a neutron reflector and moderator. The present paper proposes using a new, heavy element as neutron moderator and reflector, namely, “radiogenic lead” with dominant content of isotope 208Pb. Radiogenic lead is a stable natural lead. This isotope is characterized by extremely low micro cross-section of radiative neutron capture (~0.23 mb) for thermal neutrons, which is smaller than graphite and deuterium cross-sections. The reflector-converter for a fast reactor core is the structure capable of transforming some part of prompt neutrons leaked from the core into the reflected neutrons with properties similar to those of delayed neutrons, that is, sufficiently large contribution to reactivity at the level of effective fraction of delayed neutrons and relatively long lifetime, comparable with lifetimes of radionuclides-emitters of delayed neutrons. It is evaluated that the use of radiogenic lead makes it possible to slow down the chain fission reaction on prompt neutrons in the fast reactor. This can improve the fast reactor safety and reduce some requirements to the technologies used to fabricate fuel for the fast reactor.

scholarly journals Radiative neutron capture cross sections onLu176at DANCE

2016 ◽  
Vol 93 (3) ◽  
Author(s):  
O. Roig ◽  
M. Jandel ◽  
V. Méot ◽  
E. M. Bond ◽  
T. A. Bredeweg ◽  
...  
Keyword(s):  
Cross Sections ◽  
Neutron Capture ◽  
Capture Cross ◽  
Radiative Neutron ◽  
Radiative Neutron Capture ◽  
Capture Cross Sections

The (??SF) Method - Determination of Radiative Neutron Capture Cross Sections for Unstable Nuclei

2011 ◽  
Vol 59 (2(3)) ◽  
pp. 1713-1716 ◽  
Author(s):  
H. Utsunomiya ◽  
S. Goriely ◽  
H. Akimune ◽  
H. Harada ◽  
F. Kitatani ◽  
...  
Keyword(s):  
Cross Sections ◽  
Neutron Capture ◽  
Capture Cross ◽  
Unstable Nuclei ◽  
Radiative Neutron ◽  
Radiative Neutron Capture ◽  
Capture Cross Sections

Activation-measured radiative neutron-capture cross sections for236U,238U, and237Np

1988 ◽  
Vol 65 (5) ◽  
pp. 920-924 ◽  
Author(s):  
N. N. Buleeva ◽  
A. N. Davletshin ◽  
A. O. Tipunkov ◽  
S. V. Tikhonov ◽  
V. A. Tolstikov
Keyword(s):  
Cross Sections ◽  
Neutron Capture ◽  
Capture Cross ◽  
Radiative Neutron ◽  
Radiative Neutron Capture ◽  
Capture Cross Sections

Unprotected Loss of Flow Analysis of a Million Kilowatt Traveling Wave Reactor Core

2017 ◽  
Author(s):  
Wenjun Hu ◽  
Pengrui Qiao
Keyword(s):  
Fast Reactor ◽  
Traveling Wave ◽  
Nuclear Reactor ◽  
Flow Analysis ◽  
Reactor Core ◽  
Travelling Wave ◽  
Nuclear Nonproliferation ◽  
Utilization Rate ◽  
Technological Level ◽  
Long Lifetime

Traveling wave reactor (TWR) is an innovation concept nuclear reactor, through the once-through deep burning, the proliferation of fuel can be achieved and the utilization rate of Uranium can be increased. TWR has the characteristics of long lifetime, deep burn up and nuclear nonproliferation, because of its physical character, which makes it to be an attractive innovation concept fast reactor. The China institute of atomic energy (CIAE) has designed a million kilowatt TWR core based on a breeding and burn principle, which has considered the current technological level of sodium cooled fast reactor. In this paper, based on the TWR core design scheme, considered the design of fuel assembly, neutronics and thermal-hydraulic, analyzed the Unprotected loss of flow (ULOF) accident in the TWR core with the SAS4A code, through which research about the transient safety characteristics of a million kilowatt travelling wave reactor core has been done. Analysis shows that the peak temperature of fuel, cladding and coolant in the TWR core have a certain margin from the safety limits through the negative feedback of itself in the ULOF accident, the core of the million kilowatt TWR demonstrates a good safety performance.

The Generation of Few-Group Constants for Fast Reactor Analysis

2016 ◽  
Author(s):  
Xianan Du ◽  
Liangzhi Cao ◽  
Youqi Zheng
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Cross Sections ◽  
Fast Reactor ◽  
Monte Carlo Calculation ◽  
Anisotropic Scattering ◽  
Slowing Down ◽  
Nodal Method ◽  
Reactor Calculation ◽  
Broad Energy

A way to generate the few-group cross sections for fast reactor calculation is presented in this paper. It is based on the three steps computational scheme. In the first step, the ultrafine method is used to solve the slowing down equation based on the ultrafine group cross section generated by NJOY. Optional 0D or 1D calculation is used to collapse energy group into broad energy groups. In the second step, the 2D RZ calculation using SN method is performed to obtain the space dependent neutron spectra to collapse broad energy groups into few groups. The anisotropic scattering is well handled by the direct SN calculation. Finally, the full core calculation is performed by using the 3D SN nodal method. The results are compared with continuous energy Monte-Carlo calculation. Both the cross section generated in the first step and the final keff in the last step are compared. The results match well between the three steps calculation and Monte-Carlo calculation.

scholarly journals On a significant slowing-down of the kinetics of fast transient processes in a fast reactor

2020 ◽  
Vol 6 (4) ◽  
pp. 295-298
Author(s):  
Gennady G. Kulikov ◽  
Anatoly N. Shmelev ◽  
Vladimir A. Apse ◽  
Evgeny G. Kulikov
Keyword(s):  
Fast Reactor ◽  
Dead Time ◽  
Reactor Core ◽  
Atomic Weight ◽  
Neutron Lifetime ◽  
Fission Reaction ◽  
Delayed Neutrons ◽  
Reactor Kinetics ◽  
The Dead ◽  
Kinetics Of

The kinetics of nuclear reactors is determined by the average neutron lifetime. When the inserted reactivity is more than the effective delayed neutron fraction, the reactor kinetics becomes very rapid. It is possible to slow down the fast reactor kinetics by increasing the neutron lifetime. The authors consider the possibility of using the lead isotope, 208Pb, as a neutron reflector with specific properties in a lead-cooled fast reactor. To analyze the emerging effects in a reactor of this type, a point kinetics model was selected, which takes into account neutrons returning from the 208Pb reflector to the reactor core. Such specific properties of 208Pb as the high atomic weight and weak neutron absorption allow neutrons from the reactor core to penetrate deeply into the 208Pb reflector, slow down in it, and have a noticeable probability to return to the reactor core and affect the chain fission reaction. The neutrons coming back from the 208Pb reflector have a long ‘dead-time’, i.e., the sum of times when neutrons leave the reactor core, entering the 208Pb reflector, and then diffuse back into the reactor core. During the ‘dead-time’, these neutrons cannot affect the chain fission reaction. In terms of the delay time, the neutrons returning from the deep layers of the 208Pb reflector are close to the delayed neutrons. Moreover, the number of the neutrons coming back from the 208Pb reflector considerably exceeds the number of the delayed neutrons. As a result, the neutron lifetime formed by the prompt neutron lifetime and the ‘dead-time’ of the neutrons from the 208Pb reflector can be substantially increased. This will lead to a longer reactor acceleration period, which will mitigate the effects of prompt supercriticality. Thus, the use of 208Pb as a neutron reflector can significantly improve the fast reactor nuclear safety.

Radiative capture of fast neutrons in 160Gd

1988 ◽  
Vol 66 (4) ◽  
pp. 330-333 ◽  
Author(s):  
R. K. Y. Singh ◽  
M. Afzal Ansari ◽  
R. P. Gautam ◽  
I. A. Rizvi ◽  
S. Kailas
Keyword(s):  
Cross Sections ◽  
Neutron Capture ◽  
Radiative Capture ◽  
Fast Neutrons ◽  
Activation Technique ◽  
Present Measurement ◽  
Radiative Neutron ◽  
Experimental Values ◽  
Radiative Neutron Capture ◽  
Capture Cross Sections

Radiative neutron capture cross sections for 160Gd have been measured at eight different neutron energies: 0.46 ± 0.04, 0.57 ± 0.04, 0.75 ± 0.04, 0.97 ± 0.20, 1.22 ± 0.19, 1.52 ± 0.17, 2.22 ± 0.17, and 3.05 ± 0.18 MeV. The activation technique has been employed in the present measurement. Our experimental values are compared with the theoretical values calculated using the FISPRO II code, using the most recent set of parameters available in the published literatures.

scholarly journals Safety features of fast reactor with heavy atomic weight weakly neutron absorbing reflector

2020 ◽  
Vol 6 (1) ◽  
pp. 15-21
Author(s):  
Gennady G. Kulikov ◽  
Anatoly N. Shmelev ◽  
Vladimir A. Apse ◽  
Evgeny G. Kulikov
Keyword(s):  
Fast Reactor ◽  
Reactor Core ◽  
Atomic Weight ◽  
Reactor Safety ◽  
Delayed Neutrons ◽  
Safety Features ◽  
Kinetics Of ◽  
Reactivity Accident ◽  
Neutron Absorption Cross Section

The purpose of the present study is the justification of the possibility of improving fast reactor safety by surrounding reactor cores with reflectors made of material with special neutron physics properties. Such properties of 208Pb lead isotope as heavy atomic weight, small neutron absorption cross section, and high inelastic scattering threshold result in certain peculiarities in neutron kinetics of the fast reactor equipped with 208Pb reflector, which can significantly enhance reactor safety. The reflector will also make possible generation of additional delayed neutrons characterized by the “dead” time. This will improve the resistibility of the fission chain reaction to stepwise reactivity excursions and exclude prompt supercriticality. Let us note that generation of additional delayed neutrons can be shaped by reactor designers. The relevance of the study amounts to the fact that generation of additional delayed neutrons in the reflector will make it possible mitigating the consequences of a reactivity accident even if the introduced reactivity exceeds the effective fraction of delayed neutrons. At the same time, the role of the fraction of delayed neutrons as the maximum permissible reactivity for reactor safety is depreciated. Scientific originality of the study pertains to the fact that the problem of yield of additional neutrons with properties close to normal delayed neutrons, has not been posed before. The authors suggest a new method for enhancing safety of fast reactors by increasing the fraction of delayed neutrons due to the time delay of prompt neutrons during their transfer in the reflector. In order to benefit from the expected advantages, the following combination is acceptable: lead enriched by 208Pb is used as a neutron reflector while natural lead or other material (sodium, etc.) is used as a coolant in the reactor core.

Direct-semidirect and compound contributions to radiative neutron capture cross sections

1980 ◽  
Vol 339 (2) ◽  
pp. 205-218 ◽  
Author(s):  
A. Lindholm ◽  
L. Nilsson ◽  
M. Ahmad ◽  
M. Anwar ◽  
I. Bergqvist ◽  
...  
Keyword(s):  
Cross Sections ◽  
Neutron Capture ◽  
Capture Cross ◽  
Radiative Neutron ◽  
Radiative Neutron Capture ◽  
Capture Cross Sections
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