8.50. The ability to access various data bases in information centers by computerized communications networks is a major convenience. In most cases, the computerized data base with interactive capabilities is maintained by the responsible center, while access is obtained by means of a com­mercial communications network such as SPRINTNET or ВТ TYMNET [9]. Generally, a commercial service provider serves as an intermediate link between the communication network, which is “dialed up” by the user, and the various data bases. Such providers, which offer numerous information and search services, generally provide catalogs of data bases that are available through them [10]. A given data base may be offered by more than one provider. In some cases, a provider may also offer communication network service.

8.51. On-line interactive access to some data bases may be available directly by telephone. For example, the U. S. Department of Energy pro­vides an on-line search service known as FEDIX for universities and other research organizations. No registration or access fees are required. The Federal Telecommunications Service (FTS) also provides network access to many data bases to U. S. government contractors. RECON, developed by the Technical Information Service for Department of Energy contractors and other agencies, is an interactive search system for a large number of data bases of interest to the nuclear engineering community. Included are such areas as safety information, codes available at the National Energy Software Center (§8.33), and electric power data.

8.52. The NUCLEAR NETWORK, operated by the Institute of Nu­clear Power Operations (INPO), provides direct communication between reactor licensees, reactor vendors, and other nuclear power-related groups such as the Nuclear Safety Analysis Center of the Electric Power Research Institute. Most use is devoted to communications rather than literature searches.

8.53. The INTERNET, when it began in 1969 as ARPANET, linked a few universities, government agencies, and defense-related laboratories. During recent years, it has grown at a rapid rate to accommodate com­mercial as well as institutional users and has become the world’s largest computer network. Since most networks are connected to the INTERNET, it has become in a sense a worldwide network of computer networks. A large variety of services are available through the INTERNET, including electronic mail, access to data bases, and on-line discussion groups [11]. Public access is available through commercial providers (§8.50).

Information Age Challenges

8.54. Making effective use of all of the information resources available to help the engineer solve a given problem is somewhat of a challenge. The discussion above is intended only as an introduction to the types of services available, which are being continually expanded and updated. Therefore, guidance from an information service professional or technical librarian is desirable.

GENERAL REFERENCES

Beam, W. R., “Systems Engineering: Architecture and Design,” McGraw-Hill Book Co., 1990.

Blanchard, B. S., and W. J. Fabrycky, “Systems Engineering and Analysis,” 2nd Ed., Prentice Hall, 1990.

Boardman, J., “Systems Engineering: An Introduction,” Prentice Hall, 1990.

Lewis, W. P., “Fundamentals of Engineering Design,” Prentice Hall, 1989.

Papalambros, P. Y., and D. J. Wilde, “Principles of Optimal Design: Modeling and Computation,” Cambridge University Press, 1988.

Ralston, A., and E. D. Reilly, eds., “Encyclopedia of Computer Science,” 3rd Ed., Van Nostrand Reinhold Co., 1993.

Ray, M. S., “Elements of Engineering Design: An Integrated Approach,” Prentice Hall, 1985.

REFERENCES

1. J. G. Ecker and M. Kupferschmid, “Introduction to Operations Research,” John Wiley & Sons, 1988.

2. J. Boardman, “Systems Engineering: An Introduction,” Prentice Hall, 1990.

3. T. J. Downar and A. Sesonske, “Light Water Reactor Fuel Cycle Optimi­zation: Theory versus Practice,” Adv. Nucl. Sci. Technol., 20, 71 (1988).

4. D. T. Pham, Ed., “Artificial Intelligence in Design,” Springer-Verlag, 1991; M. Sharpies et al., “Computers and Thought,” MIT Press, 1989.

5. M. D. Rychener, “Expert Systems for Engineering Design,” Academic Press,

1988; J. A. Bernard and T. Washio, “Expert System Applications within the Nuclear Industry,” American Nuclear Society, 1989.

6. R. E. Uhrig, Nucl. Safety, 32, 68 (1991); P. D. Wasserman, “Neural Com­puting: Theory and Practice,” Van Nostrand Reinhold Co., 1990.

7. A. G. Parlos et al., Trans. Am. Nucl. Soc., 63, 109 (1991).

8. J. Jedruch, “Nuclear Engineering Data Bases, Standards, and Numerical Analysis,” Van Nostrand Reinhold Co., 1985; D. N. Chorafas and S. J. Legg., “The Engineering Data Base,” Butterworth, 1988; M. Edelhart and O. Davies, “Omni Online Database Directory,” Collier Macmillan Publishers, 1984.

9. U. S. Sprint, 12490 Sunrise Valley Drive, Reston VA 22096 (800) 736-1130; ВТ Tymnet, Inc., P. O. Box 49019, San Jose, CA 95161, (800) 872-7654.

10. DIALOG Information Services, Inc., 3460 Hillview Avenue, Palo Alto, CA 94304, (800) 334-2564; ORBIT Search Service, 8000 Westpark Drive, Mc­Lean, VA 22102, (800) 456-7248.

11. T. L. LaQuey, “Internet Companion: A Beginner’s Guide to Global Net­working,” Addison-Wesley Publishing Co., 1993.

INTRODUCTION

The Role of Energy Transport in Reactor Design

9.1. Most of the fission reaction energy deposited in fuel is immediately converted to heat. If the fuel is to remain at steady state (constant tem­perature), the heat must be transported away at the same rate as it is generated. Although we have seen that negative reactivity feedback, if present, tends to limit power increases, it is essential for the heat generation — heat removal rate balance to be maintained, to prevent temperatures that might result in the failure of fuel and structural materials. Thus, the design of the core depends just as much on adequate heat removal as on nuclear considerations.

9.2. Effective heat removal is a function of many design parameters, including the fuel geometry, coolant flow characteristics, and properties of materials, as well as related neutronic behavior. In many aspects of the design, conventional engineering principles of heat transfer and fluid me­chanics are applicable. The term thermal-hydraulics is commonly used to describe the effort involving the integration of heat-transfer and fluid me­
chanics principles to accomplish the desired rate of heat removal from the core under both operating and accident conditions. The purpose of this chapter is to introduce this area of nuclear reactor engineering.

9.3. Various accidental causes of a mismatch between the fuel heat generation and heat removal capabilities of the coolant leading to reactor damage are carefully analyzed as part of the required safety analysis to be discussed in Chapter 12. Of particular concern are events that lead to a reduction in the coolant mass flow rate. Since each unit mass of coolant would then receive more energy, boiling is a probable consequence. Such a transition to a two-phase system would result in an increase in flow resistance, further aggravating the unstable situation. Therefore, the thermal — hydraulics of two-phase systems plays an important role in reactor design. Analysis is required for the design of safety features which are provided in a reactor plant to reduce the consequences of a serious accident in which the core might be damaged. Although the relevant thermal-hydraulics basics will be discussed in this chapter, treatment of the design applications will be deferred until Chapter 12.