Category Archives: NUCLEAR REACTOR ENGINEERING

Passive Features and System Safety

15.46. The inherent characteristics of the HTGR concept provide the safety basis for the MHTGR system. First of all, graphite is stable at high temperatures and has a high heat capacity, which assures that core tem­perature transients will be slow and readily controllable. Helium is inert both chemically and neutronically. Therefore, coolant interactions with materials during the course of an […]

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Plant Aging

14.41. When present nuclear power plants were put into service, a 40- year operating lifetime was projected, essentially on an arbitrary basis. However, a maximum of 40 years was established by Congress in 1954 as the duration of an operating license. With no new plants being built and some plants approaching 30 years of service, operating license renewal for an […]

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Other Issues

15.77. Although it has been possible to eliminate most of the active safety subsystems in the passive plants, the entire plant remains a very sophisticated complex system. Therefore, plant reliability and its effect on the plant availability factor is an issue. There are differences among the concepts described regarding the amount of design innovation involved. Proponents of the AP600 and […]

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SIMPLIFIED BOILING WATER REACTOR. Introduction

15.23. The Simplified boiling-water reactor (SBWR) is a 600-MW(el) reactor which features natural circulation and passive features to enhance safety and simplify system design. An assembly view of the vessel and internals is shown in Fig. 15.3. Noteworthy is a chimney section above the core to promote the natural circulation of the coolant. As a result, the reactor pressure vessel […]

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Fault Tree Analysis

12.212. Fault tree analysis, which is essentially a graphical communi­cation tool based on Boolian algebra, is a key ingredient of reliability analysis and risk assessment. It has the value of identifying weak links in complex system interactions as well as providing insight into system be­havior. Since risk is determined by relating the system failure probability to consequences, fault tree analysis […]

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Economic Potential

15.50. The MHTGR concept benefits from the same advantages of standardization, factory fabrication, and system simplification that apply to other advanced designs having about the same electrical capacity. Al­though estimated capital cost requirements are slightly higher than for the other designs, they are probably within the error range associated with all such estimates. It should be noted that the MHTGR […]

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Protection Against Sabotage

12.251. In order to provide protection against possible sabotage, the reactor installation must be enclosed within at least two separate barriers with a “protected area” between them. An isolation zone, clear of all objects, must surround the protected area. Both the protected area and the isolation zone must be illuminated at night and continuously monitored to detect the presence of […]

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