scholarly journals Resolving Nuclear Reactor Lifetime Extension Questions: A Combined Multiscale Modeling and Positron Characterization approach

2004 ◽  
Author(s):  
B Wirth ◽  
P Asoka-Kumar ◽  
A Denison ◽  
S Glade ◽  
R Howell ◽  
...  
Keyword(s):  
Multiscale Modeling ◽  
Nuclear Reactor ◽  
Lifetime Extension

scholarly journals MATERIAL ISSUES FOR CURRENT AND ADVANCED NUCLEAR REACTOR DESIGNS

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Peter Hosemann ◽  
Jasmina Vujić
Keyword(s):  
Nuclear Reactor ◽  
Prolonged Exposure ◽  
Liquid Metals ◽  
Radiation Environment ◽  
High Radiation ◽  
Nuclear Systems ◽  
Temperature And Pressure ◽  
Pressure Stress ◽  
Liquid Salts ◽  
Lifetime Extension

In all engineering applications, design and materials together determine the functionality and reliability of a device. This is particularly important in nuclear systems where the materials are pushed to their limits and phenomena not present anywhere else occur. In nuclear systems a combination of high temperature and pressure, stress, corrosive environment and high radiation environment combined causes significant materials challenges. Majority of commercial LWRs today are licensed for 40 years of operation, but many of them undergo lifetime extension to 60 or possibly 80 years. Materials degradation has always been a significant issue. However, due to the lifetime plant extension, finding materials that could sustain prolonged exposure to these extreme conditions has become a significant problem. In addition to the materials challenges in current LWRs, advanced reactors usually deal with even more difficult issues due to their operational requirements. Unusual heat transport media, such as liquid metals, liquid salts or other types of coolants, lead to a whole new set of material challenges. While corrosion has been the main issue, much higher operating temperatures create additional difficulties. In this paper, we present an overview of materials issues for current and advanced nuclear reactor designs.

A Conceptual Multiscale Entropy Production Approach for Assessing Thermal Hydraulics Characteristics in Nuclear Reactor Systems

2016 ◽  
Author(s):  
Yu Ji ◽  
Hao-Chun Zhang ◽  
Guo-Qiang Xu ◽  
Yi-Ning Zhang ◽  
Xu-Wei Wang
Keyword(s):  
Entropy Production ◽  
Multiscale Modeling ◽  
Nuclear Reactor ◽  
Current Approach ◽  
Multiscale Entropy ◽  
Thermal Hydraulics ◽  
Hydraulic Characteristics ◽  
Local Component ◽  
Hydraulic Processes ◽  
Production Approach

Thermal Hydraulics (T-H) process exerts important effect on nuclear reactor systems. Due to their complexity, it is necessary to propose an appropriate approach for modeling and investigating the processes, such as multiscale modeling technique. The current work attempts to provide a scheme of conceptual multiscale entropy production approach in view of descriptions of thermal hydraulic characteristics in nuclear reactor system at local, component and system scales. Based on some fundamental principles, the optimal thermal hydraulics design (OTHD) procedure in implementing the approach is established. Moreover, two instances are considered to show the applicability of the current approach, with respect to local and system scale. In addition, the approach proposed would contribute to make deeper understanding of the thermal hydraulic processes.

scholarly journals Wavelet operator for multiscale modeling of a nuclear reactor

2018 ◽  
Vol 50 (5) ◽  
pp. 698-708
Author(s):  
Vineet Vajpayee ◽  
Siddhartha Mukhopadhyay ◽  
Akhilanand Pati Tiwari
Keyword(s):  
Multiscale Modeling ◽  
Nuclear Reactor ◽  
Wavelet Operator

In situ TEM studies of irradiation effects for materials improvement

1991 ◽  
Vol 49 ◽  
pp. 452-453
Author(s):  
Charles W. Allen
Keyword(s):  
Nuclear Reactor ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Point Of View ◽  
In Situ Tem ◽  
Irradiation Effects ◽  
Tem Analysis ◽  
Radiation Induced ◽  
Analytical Tools

Irradiation effects studies employing TEMs as analytical tools have been conducted for almost as many years as materials people have done TEM, motivated largely by materials needs for nuclear reactor development. Such studies have focussed on the behavior both of nuclear fuels and of materials for other reactor components which are subjected to radiation-induced degradation. Especially in the 1950s and 60s, post-irradiation TEM analysis may have been coupled to in situ (in reactor or in pile) experiments (e.g., irradiation-induced creep experiments of austenitic stainless steels). Although necessary from a technological point of view, such experiments are difficult to instrument (measure strain dynamically, e.g.) and control (temperature, e.g.) and require months or even years to perform in a nuclear reactor or in a spallation neutron source. Consequently, methods were sought for simulation of neutroninduced radiation damage of materials, the simulations employing other forms of radiation; in the case of metals and alloys, high energy electrons and high energy ions.

Eds Of Radioactive Particles By Self-Induced Fluorescence

1990 ◽  
Vol 48 (2) ◽  
pp. 238-239
Author(s):  
Gregory L. Finch ◽  
Richard G. Cuddihy
Keyword(s):  
Electron Beam Irradiation ◽  
Nuclear Reactor ◽  
X Rays ◽  
Reactor Accident ◽  
Internal Radiation ◽  
X Ray ◽  
External Sources ◽  
X Irradiation ◽  
Available Information ◽  
Individual Particles

The elemental composition of individual particles is commonly measured by using energydispersive spectroscopic microanalysis (EDS) of samples excited with electron beam irradiation. Similarly, several investigators have characterized particles by using external monochromatic X-irradiation rather than electrons. However, there is little available information describing measurements of particulate characteristic X rays produced not from external sources of radiation, but rather from internal radiation contained within the particle itself. Here, we describe the low-energy (< 20 KeV) characteristic X-ray spectra produced by internal radiation self-excitation of two general types of particulate samples; individual radioactive particles produced during the Chernobyl nuclear reactor accident and radioactive fused aluminosilicate particles (FAP). In addition, we compare these spectra with those generated by conventional EDS.Approximately thirty radioactive particle samples from the Chernobyl accident were on a sample of wood that was near the reactor when the accident occurred. Individual particles still on the wood were microdissected from the bulk matrix after bulk autoradiography.

Becoming the Nuclear-Front-End

2017 ◽  
Vol 47 (189) ◽  
Author(s):  
Patrick Schukalla
Keyword(s):  
Nuclear Reactor ◽  
Chemical Elements ◽  
High Technology ◽  
Power Production ◽  
Uranium Mining ◽  
Nuclear Industry ◽  
Current State ◽  
Front End ◽  
Production And Consumption ◽  
Uranium Exploration

Uranium mining often escapes the attention of debates around the nuclear industries. The chemical elements’ representations are focused on the nuclear reactor. The article explores what I refer to as becoming the nuclear front – the uranium mining frontier’s expansion to Tanzania, its historical entanglements and current state. The geographies of the nuclear industries parallel dominant patterns and the unevenness of the global divisions of labour, resource production and consumption. Clearly related to the developments and expectations in the field of atomic power production, uranium exploration and the gathering of geological knowledge on resource potentiality remains a peripheral realm of the technopolitical perceptions of the nuclear fuel chain. Seen as less spectacular and less associated with high-technology than the better-known elements of the nuclear industry the article thus aims to shine light on the processes that pre-figure uranium mining by looking at the example of Tanzania.

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