Seismic Design for Nuclear Power Plants: Book Review

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  • BOOK REVIEWS

    Seismic Design for Nuclear Power Plants

    Received J i m 9, 1972 Accepted June 14, 1972

    Seisiuic Desigir / b y Nr~clenr P O I I W Ploills. Edited by R 489 pp. $20.25

    The book is a collection of the papers given at the seminar on "Seismic Design for Nuclear Power Plants" held at Massachu- setts Institute of Technology i n the spring of 1969. The title is riot apt: only one paper i n tlie book deals with design and that confines itself to certain aspects of the design of reinforced concrete containment structures. The rest of the book is devoted to methods for determining the seismic threat at the site and the seismic loadings for wliicli tlie plant sliould be designed. Anyone who expects a distillation of tlie design experience ac- cumulated from the nuclear plants already i n operation will be disappointed. However, the book is one of the best and most read- able introductions available to the problem of determining the seismic threat at a site. I n fact tlie paper on basic concepts and important problems by Wliitman in itself constitutes a far-ranging and illuminating introdi~ction.

    Tlie papers cover three broad areas of earthquake engineering: the estimation of tlie seismic tlireat at a site, dynamic analysis. and design. The treatment of tliese areas is rather unbalanced. Many of tlie papers deal with the estimation of the seismic threat at a site. Among tliese there is a great deal of repetition i n matters of definition, procedure, and an overly f u l l treatment of tlie matter of intensity. The standard procedures fol- lowed in the U.S.A. i n estimating tlie seismic threat at a nuclear reactor site are clearly outlined by Linelian. but i n general terms. The procedure assesses the highest intensity ever experienced at a site and this intensity is considered to be related to tlie maximum probable earthquake. The practice is then followed of going one intensity higher to establish the maximum credible earthquake wl~ich is used i n the design of the Class I

    J . Hansen. General Publishing Co. Ltd., Canada. 1972,

    structures in tlie nuclear facility. Apart from tlie requirement to go one intensity higher, tlie procedures are those wliicl~ are commonly followed i n assessing tlie threat at a site for any other type of facility.

    The degree of uncertainty involved i n estimating intensity and i n correlating the intensity at a site with given earthquake sources and seismic design parameters such as ground accelerations or ground velocities indicates the great need for a probabilistic approach to the estimation of seismic threat and design seismic inputs. The probabilistic approach is treated i n a lucid and detailed manner i n papers by Cornell and Esteva. Cornell discusses the limitations of tlie deterministic approacli, introduces an ele- mentary form of risk analysis as an alternative and finally lays the groundwork for prob- abilistic models of earthquake motion. The sug- gested model is that of a non-stationary random process and is similar to that extensively used by Bolotin. Analytical treatment of this model can be used to obtain motions, variances, and probability distributions of linear structural response. Such probabilistic methods of risk analysis and seismic input specification make explicit the various sources of uncertainty and the degree to wliicli each affects the design decision. Esteva develops these models in greater detail and introduces i n actualized form the utilities (costs, benefits, and damages) implicit in various design decisions and formulates a decision-making procedure in accordance with maximum expected utility. Bayesian statistics are used to explore the wide range of lhypotl~eses and consequences resulting from tlie margin of uncertainty that may characterize the parameters of the stochastic seismicity model. I t would seem that tlie greatest bar to the use of probabilistic methods i n evaluating

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  • 522 C.-\N.ADIAN GEOTECHNIC.\L JOURNAL. VOL. 9. 19i2

    tlie se ism~c response of a nuclear power plant may be tlie psycl~ological difficulties inherent in any explicit treatnient of risks that can have dire consequences.

    The estimation of the seisniic threat at a site due to seisnio-tectonic activity must be modified by tlie effect of local site conditions. One of the inost coniprehensive papers available on tliis subject is the one presented by Roesset. While the results are limited to uniform or regularly stratified deposits of linear viscoelastic material, they sliould be adequate for determining useful estimates of tlie effect of local site conditions on eartli- quake motions. How the parameters of tlie viscoelastic model may be determined is described by Whitman in his paper on the evaluation of soil properties. Further mod- ification of tlie motion occurs due to soil- structure interaction. This is also treated by Whitman in another paper using simple mechanical models. The success of such simple models in predicting soil-structure interaction is very dependent on the ex- perience of the person constructing the model and judging the results of the analysis. By and large tliis experience does not ap- pear to be transferable between individuals. Without this experience it would probably be better to use finite element methods in which less judgement is required in the construction of a mechanical model equiva- lent to the structure and foundation soil. Structural response to seismic input is treated i n a cursory fashion by Biggs, no doubt because many books are already available on this subject. T o perform structural re- sponse analyses 11 is necessary to have a mechanical model which will adequately represent the dynamic structural behavior. Perhaps the most difficult part of tlie nuclear facility to model may be the containment structure. Pahl d i sc~~sses the niodelling of containnient structures and their modal an- alyses. The preference again is for lumped mass systems and exterior springs. The stiff- nesses between tlie interacting lumped masses O F the containnient structure are determined by bean1 theory. As pointed out by Palil, the most diff ic~~lt phase of the dynamic analysis of the containnient structure I S the selection of an adequate mathematical model. Once again it would be interesting to have

    an assessment of the ~ ~ t i l i t y of finite elenient representation in this case.

    One of the more interesting of the an- alytical papers is the one by Biggs and Roesset on the seisniic analysis of equipmelit mounted on a massive structure. Formal analytical treatnient of tliis problem can be extreniely tedious and numerical results difficult to determine, usually because of tlie small mass of the equipment in relation to the mass of the structure. With a great deal of ingenuity a practical and simple approach has been developed to determine tlie dynamic response of equipment. The method in cer- tain limiting cases coincides with known theoretical results. In effect, a method is presented for proceeding from a ground response spectrum to a structural response spectrum to an e q ~ ~ i p m e n t response spectrum. The final analyses curves which are presented are dependent on the characteristics of the El Centro earthquake motions. It is not clear how useful they might be for other types of motion.

    The only design paper is tlie one by Holley which focuses on auestions of resistance to tlie internal forces associated with loading of containnient structures. There is a brief discussion of steel containment shells with separated concrete shield structures. Con- crete containnient structures are dealt with in considerable detail. They must be designed not only to avoid gross rupture but also to maintain a gas-tight condition in the con- tainment liner. The latter requirement neces- sitates the avoidance of local strain dis- continuities in the liner which requires that no large cracks develop in the concrete o r large slips along the cracks. The effectiveness of various multidirectional rebars with and without prestressing tendons in resisting membrane stresses are evaluated.

    Finally, two papers present the results of some recent research. Aki presents a method for determining earthquake n~ot ions from the geometrical and mechanical properties of faults usins dislocation theory. This theory has recently been applied with some success to the prediction of motions resulting froni the San Fernando Earthquake of 1971. Arias presents one of the most comprehensive discussions in recent years of earthquake intensity and proposes a new definition

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  • 13001; REVIEIVS 523

    based on energy dissipation per unit structural inputs, but its contribution to the specific mass which has some very interesting pos- problem of the design of nuclear power sibilities. plants is slight.

    I n conclusion, the book is an extreniely valuable and interesting contribution t o the literature on the estimation of seismic risk and the determination of seisniic design

    W. D. LIAM FINN, Fuculty of' Applied Science,

    University of' Bri t ish Co lu~ i ih in , V (~ncouwr 8, Cnmda .

    Stress-Strain Behaviour of Soils

    Received May 12, 1977 Accepted May 31, 1972

    S/~ms-S/r.riiir Bclinvior~r of'Soi1.s. Edited by R.H. G. Parry. G. T. Foulis Co. Ltd., Great Britain. 1972. 752 pp. S35.00.

    This book contains the proceedings of the symposium held at Cambridge Univer- sity in 1971 as a memorial to Professor K. H . Roscoe who, until his untimely death, was Head of tlie Soil Mechanics section of the University Engineering Department of Cambridge University. The symposium was appropriately organized around the general topic of "Stress-Strain Beliaviour of Soils" to whicli Professor Roscoe, his colleagues, and their students at Cambridge University made very many valuable contributions, a large proportion of which were 'firsts' in this field. Tlie symposium was a researcli symposium, rather than an engineering con- ference, witli tlie great majority (34 of 36) of tlie persons making prepared contributions coming from Great Britain. As a result the volume will be of interest and value primarily to researcli workers, and its contents are limited to current work in Great Britain, whicli remains of very high standard.

    Tlie symposium volume is divided into six sections, reflecting the six technical sessions of whicli tlie symposium was com- posed. The first three sections deal with "The meaning and measurement of basic soil parameters" and make LIP more than half of the volume, and the following three sections deal with "Large scale laboratory measurement of soil performance", "Me- thods of solution of boundary value prob- lems", and "The relevance of laboratory measured parameters in field studies". Each section consists of a major paper prepared

    by tlie discussion leader for that particular session of the symposium, five prepared contributions f rom different authors, and a record of the open discussion for the session. The total length of the volume is 752 pages, and the quality of tlie printing and, for the most part, the figures is excellent. The price is approximately $35.00.

    The contents of the symposium are too numerous and too varied t o permit detailed discussion and therefore only general com- ments will be offered. First, t o the reviewer who did not attend tlie symposium, there appears to be little close relationship of many of tlie contributions to tlie main paper for each session. The result is tha t the reading is disjointed. Second, there is an unfortunate neglect throughout much of the volume of work which has been done outside of Great Britain, to the extent tha t tlie symposium volume is rather provincial in its coverage. Third, some of the most interesting contributions came from a new generation of research workers throughout Great Britain and the impression which was gained in reading the volume was that the days might be over when soil mechanics tliouglit is dominated by the schools a t Cambridge, Imperial College and Manchester in the persons of Roscoe, of Skempton and Bishop and of Rowe.

    The recommandations that the reviewer will make are based on such practical con- siderations as: the half-life is very short of research information such as that found

    Cmndk111 Gcotrcl~nical Journal . 9. 523 ( t 9 i 2 )

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