Determination of Neutron Damage Parameters for Irradiation Embrittlement

2009 ◽  
pp. 55-55-9
Author(s):  
EP Lippincott ◽  
WN McElroy
Keyword(s):  
Irradiation Embrittlement ◽  
Neutron Damage

Preliminary Results On Ultrasonic Attenuation Detection Of Neutron Irradiation Embrittlement Of Nuclear Reactor Steel

1997 ◽  
Vol 503 ◽  
Author(s):  
A. L. Hiser ◽  
R. E. Green
Keyword(s):  
Fracture Toughness ◽  
Neutron Irradiation ◽  
Pressure Vessel ◽  
Ultrasonic Attenuation ◽  
Reactor Pressure Vessel ◽  
Irradiation Embrittlement ◽  
Preliminary Results ◽  
Nondestructive Determination ◽  
Reactor Pressure

ABSTRACTNeutron bombardment of reactor pressure vessel (RPV) steels causes reductions in fracture toughness in these steels, termed neutron irradiation embrittlement. Currently there are no accepted methods for nondestructive determination of the extent of the irradiation embrittlement nor the actual fracture toughness of the reactor pressure vessel. This paper provides preliminary results of an effort addressing the use of ultrasonic attenuation as a suitable parameter for nondestructive determination of irradiation embrittlement in RPV steels.

scholarly journals Experimental determination of the critical cavity radius in Fe-10% Cr for ion irradiation

1984 ◽  
Vol 42 ◽  
pp. 484-485
Author(s):  
L. L. Horton
Keyword(s):  
Critical Radius ◽  
Ion Irradiation ◽  
Cavity Growth ◽  
High Energy ◽  
Cavity Radius ◽  
Atomic Displacements ◽  
Neutron Damage ◽  
Energy Neutron ◽  
Dimensional Instability

A major problem associated with the design of fusion reactors is high energy neutron damage to structural materials. The combination of vacancies formed by atomic displacements with gases produced by transmutation reactions can cause the formation of cavities. An important parameter in the theory of cavity growth is the radius above which the cavity exhibits bias-driven growth. If the cavity radius is less than this “critical radius,” cavities lose as many vacancies due to thermal processes as are gained from the bias-induced influx of vacancies. When bias-driven growth occurs, large amounts of cavitational swelling can result, leading to severe dimensional instability. Cavities can attain the critical radius either by an abnormally high random influx of vacancies or by absorption of gas atoms. The addition of gas atoms to a cavity reduces the value for the critical radius. If the number of gas atoms exceeds a critical number of gas atoms, then the critical radius vanishes. There is then no barrier to bias-driven growth.

scholarly journals To the issue of accuracy of determination of irradiation embrittlement coefficient

2020 ◽  
Vol 21 (3) ◽  
pp. 245-248
Author(s):  
L.I. Chyrko ◽  
◽  
V.M. Revka ◽  
Yu.V. Chaikovskyi ◽  
M.G. Goliak ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Statistical Analysis ◽  
Fast Neutron ◽  
Neutron Fluence ◽  
Reactor Vessel ◽  
Irradiation Embrittlement ◽  
Radiation Induced ◽  
The Impact ◽  
Surveillance Specimens

The paper presents the statistical analysis of experimental results of radiation-induced critical brittle temperature ΔTF shifts and reference temperatures ΔT0 obtained respectively from the impact bend and fracture toughness tests of the reactor vessel metal surveillance specimens to define the possibility of their mutual application for the irradiation embrittlement coefficient to be determined more accurately. The correlation between these parameters is shown to remain up to the accumulation of over-design fast neutron fluence.

Toughness and Embrittlement of RPV Steels Using Ultrasonic Measurements

2004 ◽  
Author(s):  
Allen L. Hiser
Keyword(s):  
Fracture Toughness ◽  
Pressure Vessel ◽  
Ultrasonic Attenuation ◽  
Reactor Pressure Vessel ◽  
Irradiation Embrittlement ◽  
Nondestructive Determination ◽  
Rpv Steel ◽  
Suitable Parameter ◽  
Reactor Pressure

Neutron bombardment of reactor pressure vessel (RPV) steels causes reductions in fracture toughness in these steels, termed neutron irradiation embrittlement. Currently there are no accepted methods for nondestructive determination of the extent of the irradiation embrittlement nor the actual fracture toughness of the reactor pressure vessel. This paper summarizes the findings from an effort addressing the use of ultrasonic attenuation as a suitable parameter for nondestructive determination of irradiation embrittlement in RPV steels. The materials examined in this study include one heat of RPV steel that was heat treated to induce changes in its fracture toughness, several heats of RPV steel irradiated to assess neutron embrittlement changes in fracture toughness, and a matrix of RPV steels (in the unirradiated condition) with a range of as-fabricated fracture toughness levels.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Large-scale Motion of Solar Filaments

2000 ◽  
Vol 179 ◽  
pp. 205-208
Author(s):  
Pavel Ambrož ◽  
Alfred Schroll
Keyword(s):  
Magnetic Flux ◽  
Proper Motion ◽  
Time Scale ◽  
Large Scale ◽  
Accuracy Of Measurements ◽  
Solar Filaments ◽  
General Movement ◽  
Scale Motion ◽  
Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

Practical Realization of a Reference System for Earth Dynamics by Satellite Methods

1975 ◽  
Vol 26 ◽  
pp. 341-380 ◽  
Author(s):  
R. J. Anderle ◽  
M. C. Tanenbaum
Keyword(s):  
Reference Frame ◽  
Polar Motion ◽  
Pole Position ◽  
Control Points ◽  
Significant Information ◽  
Crustal Motion ◽  
Average Reference ◽  
Future Data ◽  
Existing Data

AbstractObservations of artificial earth satellites provide a means of establishing an.origin, orientation, scale and control points for a coordinate system. Neither existing data nor future data are likely to provide significant information on the .001 angle between the axis of angular momentum and axis of rotation. Existing data have provided data to about .01 accuracy on the pole position and to possibly a meter on the origin of the system and for control points. The longitude origin is essentially arbitrary. While these accuracies permit acquisition of useful data on tides and polar motion through dynamio analyses, they are inadequate for determination of crustal motion or significant improvement in polar motion. The limitations arise from gravity, drag and radiation forces on the satellites as well as from instrument errors. Improvements in laser equipment and the launch of the dense LAGEOS satellite in an orbit high enough to suppress significant gravity and drag errors will permit determination of crustal motion and more accurate, higher frequency, polar motion. However, the reference frame for the results is likely to be an average reference frame defined by the observing stations, resulting in significant corrections to be determined for effects of changes in station configuration and data losses.

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