Negative reactivity determination by source jerk method

1966 ◽  
Vol 20 (1) ◽  
pp. 96-98
Author(s):  
F. S. Drozdov ◽  
A. S. Rychev
Keyword(s):  
Negative Reactivity ◽  
Reactivity Determination

Antiphospholipid Syndromes with Anti-Human β2-Glycoprotein I Antibodies despite Negative Reactivity in Conventional aPL and LA Assays

1997 ◽  
Vol 77 (05) ◽  
pp. 1037-1038 ◽  
Author(s):  
Viviane Guérin ◽  
Anne Couchouron ◽  
Christine Vergnes ◽  
Eric Parrens ◽  
Jean Philippe Vernhes ◽  
...  
Keyword(s):  
Glycoprotein I ◽  
Negative Reactivity

scholarly journals Improved FAST Device for Inherent Safety of Oxide-Fueled Sodium-Cooled Fast Reactors

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4610
Author(s):  
Ahmed Amin E. Abdelhameed ◽  
Chihyung Kim ◽  
Yonghee Kim
Keyword(s):  
Operating Temperature ◽  
Reactor Core ◽  
Coolant Temperature ◽  
Inherent Safety ◽  
Oxide Fuel ◽  
Fast Reactors ◽  
Power Oscillation ◽  
Negative Reactivity ◽  
Oscillation Problem ◽  
Reactivity Coefficient

The floating absorber for safety at transient (FAST) was proposed as a solution for the positive coolant temperature coefficient in sodium-cooled fast reactors (SFRs). It is designed to insert negative reactivity in the case of coolant temperature rise or coolant voiding in an inherently passive way. The use of the original FAST design showed effectiveness in protecting the reactor core during some anticipated transients without scram (ATWS) events. However, oscillation behaviors of power due to refloating of the absorber module in FAST were observed during other ATWS events. In this paper, we propose an improved FAST device (iFAST), in which a constraint is imposed on the sinking (insertion) limit of the absorber module in FAST. This provides a simple and effective solution to the power oscillation problem. Here, we focus on an oxide fuel-loaded SFR that is characterized by a more negative Doppler reactivity coefficient and higher operating temperature than the metallic-loaded SFR cores. The study is carried out for the 1000 MWth advanced burner reactor with an oxide fuel-loaded core during postulated ATWS events that are unprotected transient over power, unprotected loss of flow, and unprotected loss of the heat sink. It was found that the iFAST device has promising potentials for protecting the oxide SFR core during the various studied ATWS events.

scholarly journals Reactivity determination in accelerator driven reactors using reactor noise analysis

2002 ◽  
Vol 17 (1-2) ◽  
pp. 19-26 ◽  
Author(s):  
Ljiljana Kostic
Keyword(s):  
Statistical Method ◽  
Nuclear Reactors ◽  
Noise Analysis ◽  
Energy Generation ◽  
Mean Value ◽  
Statistical Properties ◽  
Spallation Source ◽  
The Mean ◽  
Radioactive Sources ◽  
Reactivity Determination

Feynman-alpha and Rossi-alpha methods are used in traditional nuclear reactors to determine the subcritical reactivity of a system. The methods are based on the measurement of the mean value, variance and the covariance of detector counts for different measurement times. Such methods attracted renewed attention recently with the advent of the so-called accelerator driven reactors (ADS) proposed some time ago. The ADS systems, intended to be used either in energy generation or transuranium transmutation, will use a subcritical core with a strong spallation source. A spallation source has statistical properties that are different from those traditionally used by radioactive sources. In such reactors the monitoring of the subcritical reactivity is very important, and a statistical method, such as the Feynman-alpha method, is capable of resolving this problem.

Influence of geometry in TRIGA reactor criticality calculation and reactivity determination using Serpent 2 and MCNPX codes

2017 ◽  
Vol 11 (2) ◽  
pp. 146
Author(s):  
Sincler Peixoto De Meireles ◽  
Amir Zacarias Mesquita ◽  
Mauricio Quelhas Antolin ◽  
Daniel De Almeida Magalho ◽  
es Campolina ◽  
...  
Keyword(s):  
Triga Reactor ◽  
Reactor Criticality ◽  
Reactivity Determination

Development and Validation of a Porous Medium Computational Fluid Dynamics Model for a Jet

2008 ◽  
Author(s):  
Timothy J. Drzewiecki ◽  
Brian L. Mount ◽  
Martin Lopez de Bertodano
Keyword(s):  
Porous Medium ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Transport Model ◽  
Constitutive Relations ◽  
Symmetric Domain ◽  
Jet Mixing ◽  
Negative Reactivity ◽  
An Array Of Cylinders ◽  
Development And Validation

The fast boron shutdown injection in a PHWR consists of a jet flowing through a very large moderator tank that contains an array of cylindrical coolant channels. The accurate prediction of the turbulent jet mixing is required to determine an accurate distribution of boron inside the moderator tank to model the insertion of negative reactivity into the reactor during fast shutdown. A CFD code is used to determine the distribution of boron in the moderator tank. The flow is analyzed with a porous medium model based on volume averaged momentum, turbulent kinetic energy, and turbulence dissipation equations. The additional source terms arise due to the averaging must be constituted. The constitutive relations that are implemented in the present model are: (i) the drag force on an array of cylinders for the momentum equations and (ii) the additional mixing effect of the cylinders which results in the sources of turbulent kinetic energy and turbulence dissipation transport model. The CFD analysis is performed on a porous, axis symmetric domain. The CFD results are finally compared with data for the boron concentration distribution obtained in a scaled geometrically similar experiment, demonstrating the validity of the approach.

Negative reactivity in toddlers born prematurely: Indirect and moderated pathways considering self-regulation, neonatal distress and parenting stress

2013 ◽  
Vol 36 (1) ◽  
pp. 124-138 ◽  
Author(s):  
Babett Voigt ◽  
Alexa Brandl ◽  
Joachim Pietz ◽  
Sabina Pauen ◽  
Matthias Kliegel ◽  
...  
Keyword(s):  
Parenting Stress ◽  
Self Regulation ◽  
Negative Reactivity
Sign in / Sign up

Export Citation Format

Share Document