Difference between revisions of "Taxonomy"

Revision as of 07:19, 9 August 2013

Definition

Taxonomy is A structure (usually hierarchical) in which a body of information or knowledge is categorized, allowing an understanding of how that body of knowledge can be broken down into parts and how its various parts relate to each other Source: Comparative Analysis of Methods and Tools for Nuclear Knowledge Preservation

Taxonomy is Template:Taxonomy 2 Source: Planning and Execution of Knowledge Management Assist Missions for Nuclear Organizations

Summary

One paragraph summary which summarises the main ideas of the article.

Description

The word comes from the Greek τάξις, taxis (meaning ‘order’, ‘arrangement’) and νόμος, nomos (‘law’ or ‘science’). Taxonomies, or taxonomic schemes, are composed of taxonomic units known as taxa (singular taxon), or kinds of things that are arranged frequently in a hierarchical structure. Typically they are related by subtype–supertype relationships, also called parent–child relationships. In such a subtype–supertype relationship the subtype element has by definition the same constraints as the supertype element plus one or more additional constraints.

Source: Comparative Analysis of Methods and Tools for Nuclear Knowledge Preservation

Description

FRKPS taxonomy

The Vienna meeting proposed a hierarchical structure for the FRKPS taxonomy, consisting of two upper levels of the FRKPS that are represented as a two-dimensional matrix in which elements of the upper row are stages of implementation of reactor technology (1st structural level of FRKPS), and the columns under the upper row elements include topical sections corresponding to given stages of reactor technology implementation (2nd structural level of FRKPS). This matrix is shown in Fig. 1. It is proposed to divide each topical section presented in the matrix into progressively detailed subsections and connect them in such a way that each subsequent level is a more detailed presentation of the previous level. Therefore, each topical section of the upper level will have a certain branched root structure consisting of specialized topical sections.

The matrix is claimed to be versatile because its structure was developed with a hypothetical, generalized SFR power plant in mind. Moreover, this structure is applicable not only to any SFR nuclear power plant irrespective of the stage of its development, but also to any experimental fast reactor. This structure would undoubtedly be redundant with reference to some specific reactor facilities. However, this redundancy has an advantage because a given document may have information on any one of several aspects of the SFR. It should be noted that the matrix structure development is still far from complete. First, topical sections of the upper level require more development and expansion. Second, the root structure should be developed for all these sections. However, this approach to the development of FRKPS taxonomy with separation of stages and topical sections of reactor technology as shown in the matrix is considered to be highly useful. This approach, which may be called the universal stage topical hierarchical structure, (USTS), will be used in the following sections as a starting point for the development of a new FRKPS taxonomy.

FIG. 1. Structure of the two top levels of the IAEA FRKP system proposed at the consultants meeting in Vienna.

FIG. 2. First two levels of the FRKPS structure

It was implied in the Vienna meeting that the USTS would be the structure for the entire database. However, it is now proposed that the USTS be a component of the FRKPS structure. The other component would be the structure for particular reactor facilities. This approach is taken based in anticipation that some users would search by topics or disciplines, while others may search the database by a particular reactor facility.

With this two component model as a guide the following is proposed for the FRKPS taxonomy. The first two levels of this taxonomy are shown in Fig. 2.

FIG. 3. The first two levels of the USTS (stage & topic matrix).

• The top level (1st level) classifies reactor facilities into the following categories:
  • Experimental FR;
  • Demonstration and prototype nuclear power plant with FR;
  • Commercial nuclear power plant with FR;
  • General section containing information on all facilities, as well as activities performed without reference to any particular reactor facility
• The second level identifies each reactor facility (this level is absent for the general section)
• The third and further levels correspond to structural levels of USTS described below. These levels are repeated for the general section and each particular reactor facility

The USTS is applied to each reactor facility, as well as the general section. Figure 3 shows the USTS

Component for the FRKPS. It can be viewed as an expanded version of the USTS shown in Fig. 1. Each topic at the third level of the FRKPS taxonomy corresponding to the first level of the USTS is expanded to an additional level of detail related to reactor technology stages (the fourth level of the FRKPS taxonomy and the second level of the USTS). This breakdown is logical because a given topic can be a part of all stages. For example, the information on the topic 'Material Behaviour' can apply to all stages of reactor development. Thus, this structure would be convenient to specialists in certain disciplines and students searching the database.

The topical items shown in Fig. 3 are based on experience gained with SFRs, although the USTS will be capable of incorporating information from other reactor types. Thus, at the first structural level of the USTS, in Fig. 3, the following basic topical sections of fast reactor (FR) technology are listed:

1. Aspects of FR neutronics;
2. Aspects of FR thermal hydraulics and thermal physics;
3. Problems related to FR materials, including fuel, coolant and its technology, structural materials, absorbers and other auxiliary materials;
4. FR safety issues, including analysis of safety characteristics, safety systems and development of standards and regulatory documents;
5. Technological systems and components — conceptual approaches and design studies on the systems and
6. components, their specific implementation and operation modes;
7. FR control and monitoring issues, including those on related systems;
8. FR ecological aspects and environmental impact;
9. FR mathematical modelling, including calculation results, computer codes in use and their description;
10. Economic and other aspects of FR, as well as historical documents, including memoirs, photographs, movies, etc.;

Each of the topics shown in Fig. 3 is aimed at specific objectives or target functions. The target functions for each topic are given in Table 1.

The target functions for two areas need further discussion. These areas are: (1) design studies on systems and components, (2) FR mathematical modelling. These two areas of activity are closely connected and are a necessary component of many aspects of FR technology. For instance, development of nuclear fuel requires modelling and the specified performance of the fuel depends on design studies. However, these two areas of work were specified as separate topical sections because of their specific features. In Table 1 the area entitled Technological Systems and Components includes all FR systems and components except for safety systems, which are included under Safety Issues, and control and monitoring systems, which are included under Monitoring and Control. These FR technological systems and components are separate subsections of the Technological Systems and Components section.

On the basis of the SFR development history, many of the target functions are dependent on each other and a given target function may be applicable to more than one system or component. Some examples are given below:

• A controlled chain reaction is assured by a certain configuration and condition of reactor core (neutronics and thermal hydraulics) and performance of control and safety systems (monitoring and control, and safety issues);
• Decay heat removal from the reactor in the shutdown condition depends both on thermal hydraulics and safety aspects;
• For instance, the section related to mathematical modelling contains information that was developed to contribute to the solution of problems inherent in target functions defined in other FR technology areas (justification of decisions made in various aspects of FR technology, safety justification, etc.).

The above considerations demonstrate that one document may be related to several topical sections and, hence, it should be recorded in all related FRKPS sections. Thus reasonable redundancy must be allowed in the FRKPS for placement of a document (or its reference) in the different topical sections.

The list of general topical sections given in Table 1 is complemented by a section intended for accumu- lation of various facts on FR development history, such as photographs, movies, memoirs, etc. This section,

TABLE 1. TARGET FUNCTION FOR EACH ASPECT OF REACTOR TECHNOLOGY

entitled Economic and Other Aspects, could be used for additional aspects of FR technology. The provision of such a section makes it possible to ensure the preservation of a comprehensive account of all information on FR which does not fall into the other topical sections.

Subsections corresponding to some categories of materials used in FR (fuel, coolant, structural materials, absorbers and auxiliary materials) are provided in a main topical section such as Material Behaviour.

The list of topical sections shown in Fig. 3 is intended to cover all areas of reactor technology related to fast reactors. The only exceptions are issues of fuel reprocessing technology within the framework of the fuel cycle. This topic is not presented as an independent topical section in the above list, since these issues are quite specific and do not relate directly to reactor technology itself. However, some specific issues related to the fuel cycle are contained in other topical sections and these issues have been taken into account in the corresponding subsec- tions.

In order to facilitate the use of USTS during its development, it is proposed to use abbreviated titles of the 1st level sections. These abbreviations are given in Table 2

TABLE 2. ABBREVIATED TITLES OF THE FIRST LEVEL SECTIONS

The distribution of problems and the types of specialists needed to solve these problems will change with the stage of FR development. The specialists of various types who are involved, namely researchers, engineers, designers, operating personnel and regulatory body representatives will change with the degree of involvement depending on the stage. Such a division should be taken into account in the USTS. Therefore, the stages of fast reactor technology implementation are specified as the second level of USTS, in accordance with the list given in Fig. 1, excluding the Fuel Cycle stage. The stages of implementation are listed below:

1. Basic Principles: Stage of development of basic principles and concept of the future nuclear power plant;
2. R & D: Stage of R & D work for support of nuclear power plant design and design approaches used within its framework;
3. Design, Analysis, Licensing: Stage of development of nuclear power plant design and its licensing by the regulatory body;
4. Manufacturing & Construction: Stage of nuclear power plant construction, manufacture and installation of reactor components and systems;
5. Operation: Stage of nuclear power plant commissioning and operation to its final shutdown;
6. Decommissioning: Stage of development of nuclear power plant decommissioning project and its imple- mentation.

All the stages listed above are applied to each specified nuclear power plant with its FR and components. The information from the specified nuclear power plant will thus exist in the FRKPS according to the stages shown above. The stage related to the fuel cycle mentioned in Fig. 1 is somewhat special, since it deals with a different subject, namely fresh and spent fuel and a set of systems and components intended for reprocessing or storage, depending on the fuel cycle concept adopted. Hence, the stage related to the implementation of the fuel cycle was not included in the USTS.

This breakdown of nuclear power plant development into stages follows the natural sequence of events in the implementation of any nuclear power plant with its specific design of FR or reactor plant. Of course, the major part of the work in the fast reactor area is carried out within the framework of development of a specific design. However, certain analytical and experimental studies in the area of fast reactors are carried out without application to a specific design. Such information will be placed in the section related to the R & D stage without indicating a specific facility.

The first two levels adopted in the new USTS option are also represented as a stage topic matrix in Fig. 3. The root structure, the content of which is determined by the intersection of the topic section and the stage, refers to each cell of the matrix. These root structures, hereinafter called branches, have been numbered. The number of each branch is determined by the number of the section and the number of the stage to which it refers. The branches are hierarchical multi-level structures.

Some of branches in the matrix are marked with an asterisk (*) to indicate that the branch is absent due to the fact that the topic of work was not applicable at that stage. For example, Neutronics & Reactor Physics are not necessary elements of work at the Manufacturing & Construction or Decommissioning stages. The detailed structure of branches of the stage topic matrix is presented in the Annex.

In order to avoid excessive congestion of USTS, the extent of detail of the levels of its branches and related specific topical subsections is limited. The degree of detail of each branch goes down up to the level of system-functional problems related to a specific topical section, but not up to the level of specific components and elements. An exception is made for the main reactor plant components, such as steam generators (SG), intermediate heat exchangers (IHX), main circulating pumps (MCP) etc., which are also included in USTS as separate subsections. Further detail of information up to the level of specific components and elements of systems is provided by use of key words. This approach to restriction of the number of levels in the branches and optimisation of FRKPS taxonomy makes it possible to also avoid excessive redundancy in duplicating placement of documents in different sections.

In order to ensure that the topical sections in the USTS are comprehensive, some FR components are included simultaneously in more than one topical section. For instance, the core is included in the Systems & Equipment and Neutronics & Reactor Physics sections.

General-industry components and off the shelf components and systems are not included in USTS. The proposed USTS has been developed as applied to a general nuclear power plant with an FR. Thus, this structure is sufficiently comprehensive but versatile enough to allow for further necessary extension.

Source: Fast Reactor Knowledge Preservation System: Taxonomy and Basic Requirements

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