Book Reviews
Because the nuclear industry and incore instruments in particular have advanced gradually and irregularly for m a n y years , this book serves a very useful purpose of identifying progress achieved. The 11 chapters treat a broad range of parameters and disciplines associ ated with measurement of nuclear flux, temperature, pressure, flow, etc. The initial chapters introduce the general problems encountered in the extremely hostile environment of the in-core instrument. The subject treatment employs a vigorous sys tematic analysis of each instrument type, one of the strong features in the author's presentation. The description and development of theory, accompanied by i d e n t i f i c a t i o n of specific components, and assessment of strengths and weakness provide valuable information to the designer or developer. Each chapter includes an excellent bibliography for those desiring to delve further into specific areas . An in-core instrument presents an extremely challenging problem. Success for a measurement system requires ambitious, skillful effort. Mr. Bolan b r i n g s these circumstances into sharp focus after initially acquainting the reader with the effects of nuclear radiation on materials and broadly characterizing the problem areas. The book helps bridge an important gap in this field between the initial beginning and the eventual time when s u f f i c i e n t information would be available for documentation in a handbook. It points out important limitations and characteristics gleaned from review, evaluation, and projection based on information that is widely scattered in the available literature. His s u m m a r i z a t i o n of performance data in some cases from several sources provides solid, efficient use of available information. Comparison between various measurement techniques very effectively brings the v a r i o u s methods into focus. The information should save needless expense for installing costly inadequate in-core components. The book makes a valuable documentation and thought-provoking presentation of in-core instrumentation, augmented by an excellent bibliography. Workers in the nuclear field from the transducer manufacturer to the plant manager and especially the instrumentation and control engineer wilfc find this book extremely valuable.
Availability of a Special 2-unit Series System
This paper deals with some availability problems of a special 2-unit series system. The purpose is threefold: 1) To point out an interesting, practical situation of 2-unit series system in which failure of one unit shuts off the other, but not vice versa. 2) To dispel an erroneous notion that all availability expressions, ranging from the one extreme of `neither shutting off the other at failure' to the other extreme of `both shutting off the other at failure', depend only on the means of the random quantities involved. A case is shown where the availability depends on the Laplace transform of a distribution as well as on the means. 3) To establish the credibility of the two extreme cases as the tight upper and lower bounds for the intermediate cases in most practical applications. All random variables are assumed s-independent. The solution uses supplementary variables.
Availability of Some Repairable Computer Systems
A mathematical model is established for the availability of a modularly redundant repairable system which consists of many active units and one standby; coverage is considered. The hazard rates for an active unit and for the standby unit are different and are assumed to be constant. Repair time distributions are general. Availability for the system, mean system up-time, and mean system down-time are derived.