Nondestructive Characterization of Neutron Induced Embrittlement in Nuclear Pressure Vessel Steel Microstructure by Using Electromagnetic Testing
By using nuclear power for energy generation the pr essure vessel wall is exposed to neutron fluences of different levels depending on the distance to th e core. Hence materials undergo a change in their microstructure in terms of embrittlement, to be mea sured as toughness reduction and shift of the Ductile-to-Brittle Transition Temperature (DBTT) to higher temperatures. Normally plant safety concerning this change in mic rostructure is assured by destructively testing surveillance samples. These are standard te nsile and ISO V-specimen which consist of exactly the same material as the pressure vessel and its we ld metal, being exposed to accelerated irradiation rates within special irradiation channels allowing a pronounced ageing. It is demonstrated that electromagnetic parameters allow to characterize the changes in the microstructure generated through neutron irradiatio n. After a defined calibration process a quantitative characterization of the embrittlement specially in terms of the shift of the DBTT is possible. This has been demonstrated for reactor pr essu e vessel steels used in nuclear power plants o f eastern and western designs. As testing methods 3MA ( icromagnetic, Multiparameter, Microstructure and stress A nalysis) [1] and the dynamic magnetostriction using EMAT (Electromagnetic Acoustic Transducers) have been applied in a nondestructive c ombination measurement system. Further experiments show the possibility to measure 3MA and dynamic magnetostriction quantities through an 8 mm thick austenitic stainle ss steel cladding.
Nondestructive Testing with 3MA—An Overview of Principles and Applications
More than three decades ago, at Fraunhofer IZFP, research activities that were related to the application of micromagnetic methods for nondestructive testing (NDT) of the microstructure and the properties of ferrous materials commenced. Soon, it was observed that it is beneficial to combine the measuring information from several micromagnetic methods and measuring parameters. This was the birth of 3MA—the micromagnetic multi-parametric microstructure and stress analysis. Since then, 3MA has undergone a remarkable development. It has proven to be one of the most valuable testing techniques for the nondestructive characterization of metallic materials. Nowadays, 3MA is well accepted in industrial production and material research. Over the years, several equipment variants and a wide range of probe heads have been developed, ranging from magnetic microscopes with µm resolution up to large inspection systems for in-line strip steel inspection. 3MA is extremely versatile, as proved by a huge amount of reported applications, such as the quantitative determination of hardness, hardening depth, residual stress, and other material parameters. Today, specialized 3MA systems are available for manual or automated testing of various materials, semi-finished goods, and final products that are made of steel, cast iron, or other ferromagnetic materials. This paper will provide an overview of the historical development, the basic principles, and the main applications of 3MA.
An Introduction to Property Theory: Utilitarian Property Theories
As a leading property law casebook puts it, “[u]tilitarian theory is, without doubt, the dominant view of property today, at least among lawyers.” This is certainly true, but the story is also significantly more complicated. Although utilitarian analysis provides tremendous insight into the institution of property, it raises a number of important questions when treated as a comprehensive theory of property. Moreover, the term utilitarian masks a great deal of intellectual and methodological diversity. Rather than a single utilitarian theory, it is more appropriate to speak of a number of utilitarian (or even utilitarian-influenced) property theories . For our purposes, these utilitarian-influenced theories include many contemporary theories that refer to themselves as economic or welfarist . In this chapter, we will explore the broad outlines of these theories, focusing on their points of overlap and also on key areas of disagreement. A BRIEF INTRODUCTION TO UTILITARIANISM Utilitarianism is a consequentialist moral philosophy, that is, one that judges the rightness and wrongness of actions or rules or institutions by the goodness and badness of the consequences they bring about. Utilitarianism assesses the goodness or badness of consequences in terms of their tendency to maximize utility or welfare. Bernard Williams has observed that “[t]he fathers of utilitarianism thought of it principally as a system of social and political decision,” as opposed to “a system of personal morality.” As Williams correctly notes, it is sometimes hard to keep these two domains apart. Nevertheless, it is plainly as a theory of social choice that utilitarianism has been deployed in the context of property theory.