GENERIC OBSERVATIONS

The generic safety issues for LWRs compiled in Section 3 reflect the broad experience of Member States in resolving safety concerns and in maintaining improvements to current practice. As reflected in the Measures taken for these issues, most issues have been successfully addressed. The Section 3 compilation also includes those safety issues which are currently considered pending , i.e. the root causes and their resolution are in the process of being developed. For pending issues, interim judgements have been made by Member States with respect to continued safe plant operation. 

This comprehensive compilation has been found to be an appropriate basis to look for broader insights, lessons learned and trends which is the subject of this section. 

The source or sources for each issue is provided in Section 3, that is, whether operational experience, a deviation from current standards and practices or analysis gave rise to the concern. Over half the issues had operational experience as one of their sources. This is to be expected after over 30 years of worldwide nuclear power generation. The source areas of deviation from current standards and practices and analysis each were noted in about one third of the issues. The use of analysis, particularly PSA, to identify potential issues of concern which have not been observed during plant operation is considered a sign of health with respect to industry and regulatory body concern for safety. Several of the deviation issues refer to W R reactors which have recently been systematically measured against international practice. 

The following discussion is organized by grouping generic observations on the issues by the primary source of the trend or common thread observed. 

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Let us consider a generic observable v4(r). The average value of A is given by... 

Section 3 presents generic observations on safety aspects identified from the issues in Section 4, grouped according to the source of the issues. 

In shutdown conditions, there are less barriers and levels of protection available to prevent an event from developing into an accident. This is somewhat offset by the lower decay heat rate in the core which can allow longer times for operators to take corrective actions. All main safety functions can be affected as seen from generic observations of PSA studies made for different plant types. 

The response theory described in the Sect. (3.2) can be used to describe the response of the molecular solute to the macroscopic Maxwell field in the medium. More specifically, the effective response functions are the coefficients of a Fourier-perturbation expansion of the time-dependent expectation values of a generic observable X, < X(t) >=< t) X

of the molecular solute in order of the perturbing Maxwell field E ... 

A generic overview of the model can be seen on figure 1. This representation gathers the objects in object groups and gives a synthetic view of the model. It can be observed that a set... 

Pha.rma.ceutica.1 Purity. A safety profile of a generic dmg can differ from that of the brand-name product because different impurities may be present in each of the dmgs (154). Impurities can arise out of the manufacturing processes and may be responsible for adverse interactions that can occur. Eor example, serious adverse reactions (LyeU syndrome) were observed upon the use of isoxicam in 1985. These seemed to have resulted from trace elements of a manufacturing by-product that was within the manufacturing quaUty control specifications. 

Figures 3.38 and 3.39 show typical space-time patterns generated by a few r = 1 reversible rules starting from both simple and disordered initial states. Although analogs of the four generic classes of behavior may be discerned, there are important dynamical differences. The most important difference being the absence of attractors, since there can never be a merging of trajectories in a reversible system for finite lattices this means that the state transition graph must consist exclusively of cyclic states. We make a few general observations.

It would appear that the tradeoffs between these two requirements are optimized at the phase transition. Langton also cites a very similar relationship found by Crutchfield [crutch90] between a measure of machine complexity and the (per-symbol) entropy for the logistic map. The fact that the complexity/entropy relationship is so similar between two different classes of dynamical systems in turn suggests that what we are observing may be of fundamental importance complexity generically increases with randomness up until a phase transition is reached, beyond which further increases in randomness decrease complexity. We will have many occasions to return to this basic idea. 

One of the principal themes of this book is the use of CA in modeling real physical systems and dynamics. To this end, it is important to address the question of what fundamental properties of physical systems can be appropriately abstracted from nature and embodied within abstract CA constructs. As observed earlier, some properties such as homogeneity and locality are automatically built in on the generic level. Another such property, namely the reversibility of microscopic dynamics, which plays such a fundamental role in physics, has its analogue in CA dynamics as well. 

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