Soil-structure interaction parameters from finite element analysis

A series of two-dimensional finite element computer runs were made to compute the frequency dependent soil-structure interaction coefficients. Variations in the element size, mesh dimensions, boundary conditions, and soil hysteretic damping ratio to determine their influence on the computed interaction coefficients were made. From the calculations, it has been determined that the primary requirement of the mesh is a transmitting boundary formulation. For low damping conditions, roller support boundary conditions must be placed exceedingly far from the structure to ensure convergence of the results to the analytic solution. In addition, with such boundary conditions, the addition of artificial hysteretic soil damping cannot be used to simulate radiation damping behavior of the continuum. A frequency dependent criteria is also presented to determine minimum size elements that must be used in any calculation.     

Soil-structure interaction in explosive testing of model containments

The SIMQUAKE series of field tests on model containment structures provides a data base which may be used to validate analytic models of soil-structure interaction (SSI). In addition, the test produced significant evidence of nonlinear rocking response of 1/4-embedded model structures due to debonding and rebonding at the soil-structure interface. This paper describes the SIMQUAKE II test and an analytic method for soil-structure interaction based on explicit finite difference techniques, which consider both nonlinear behavior at the soil-structure interface and nonlinear constitutive behavior of the site. The analytic method is applied to two-dimensional analyses of both 1/8- and 1/12-size structures and results are compared with test measurements. Structural rocking response is shown to be sensitive to the inelastic compaction characteristic of the soil adjacent to the structure. A three-dimensional pretest analysis of the SIMQUAKE II test is also briefly reviewed.     

Soil-structure interaction of nuclear reactor structures considering through-soil coupling between adjacent structures

The theoretical problem concerning the influence of through-soil coupling between adjacent structures on the seismic loading of nuclear reactors has been investigated by considering a soil-structure interaction model in which several three-dimensional flexible structures are bonded to an elastic half-space. These structures, which are allowed to be either similar or dissimilar, are modeled as conventional discrete systems mounted on separate base slabs of close proximity. For the purpose of this study, it is assumed that the stiffness of any structure such as piping connecting the adjacent buildings is negligible.For purposes of comparison, the seismic responses of structural masses are determined both with and without the influence of nearby structures. Both transient and steady-state results are presented and discussed for some typical simplified two- and three-structure complexes. Emphasis is placed on the effects of through-soil coupling on the dynamic response of the system rather than actual magnitudes of response which have previously been treated for plants erected on a single base slab. The significant findings are that nuclear power plants can be designed to achieve a reduction in seismic loads due to interaction with neighboring structures. Conversely, improper plant design and layout may result in mutual reinforcement of resonances with increased loads.     

Soil-structure interaction analyses by finite elements — State of the art

In this paper the authors have attempted to summarize the current capability for evaluating soil-structure interaction effects during earthquakes using finite element procedures. A concise summary of methods available, together with their capabilities and relative costs is presented. It is suggested that finite element procedures provide a powerful tool for use in the design of nuclear plants, especially for embedded structures, and their applicability in this respect is illustrated by comparing computed results with those recorded in a nuclear plant during a strong motion earthquake. It is concluded that when the methods are used in conjunction with good engineering judgment and with full recognition of their limitations, they provide evaluations of response with a level of accuracy entirely adequate for engineering design.     

HBMPPT-DOSO-甲苯体系对铀(Ⅵ)的萃取及铀(Ⅵ)、钍(Ⅳ)之间的分离

以个苯甲酰基－２,４二氢－５－甲基－２－苯基－３Ｈ－吡唑硫酮－３（ＨＢＭＰＰＴ）为萃取剂、二正辛基亚砜（ＤＯＳＯ）为协萃剂,研究其在硝酸介质中对铀（Ⅵ）的萃取行为,以及萃取剂浓度、酸度等各种因素对萃取分配比的影响,以确定两种萃取剂的协同萃取及分离效果。结果表明,ＨＢＭＰＰＴ和ＤＯＳＯ有较好的协同萃取效果,一定条件下,铀（Ⅵ）、钍（Ⅳ）的分离系数可达５２３。     

Simplified soil-structure interaction analysis with strain dependent soil properties

Recent work regarding the response of above-ground soil structures, such as dams, has indicated the need to use strain dependent soil properties. Unlike other building materials soil stiffness and damping properties are highly strain dependent. The application of these concepts to problems in soil-structure interaction has also been suggested. Without commenting on the appropriateness of this extension to soil-structure interaction problems, it is suggested that answers similar to those given by the strain dependent solution of finite element models can be obtained more simply by the use of lumped-parameter impedance functions. To establish this equivalence, it is imperative that all other variables in the problem be made equal for both models; that is, the strain dependency problem must be isolated if the comparison of the two approaches is to be meaningful. The proposed method uses a damping value equal to the average strain dependent soil profile damping. The strain dependent soil profile damping values are obtained by the use of a much simpler model using one-dimensional wave propagation theory. From this same one-dimensional model, the strain dependent soil stiffness corresponding to the average top layer of soil with and without an overburden to approximate the superstructure is used in the equivalent simplified model. Several case comparisons indicate the validity of the proposed method.     

HBMPPT/TOPO/甲苯体系从硝酸介质中分离三价镅和镧系元素的研究

HBMPPT（4－苯甲酰基－2，4二氢－5－甲基－2－苯基－3H－吡唑硫酮－3）或TOPO（三正辛基氧化膦）的甲苯溶液，在HNO3介质中对三价镅 和镧系元素在所研究的pH范围内无明显的萃取能力，但当两者混合时，其协同效应可使该体系从镧系锕系混合溶液中有选择地萃取三价镅（pH3.5-4.5)，两者的分离系数达10－156，实验结果还显示，代表三价锕系元素的镅和各镧系元素与该体系的化学反应机理也有所不同。     

~(14)C─绿黄隆结合残留物的微生物释放

研究利用微生物释放土壤中的~(１４)Ｃ─绿黄隆结合残留物．结果表明,在培育５ｄ后,有３４．４０％－４０．５５％的~(１４)Ｃ－结合残留物被释放出来,以可提取态存在于土壤溶液中,其数量在以后的试验过程中变化不大。微生物释放~(１４)Ｃ－结合残留物时,主要对存在于富里酸中的结合残留物产生作用。与对照相比,利用的微生物Ｂａｃｉｌｌｕｓ ｍｅｇａｔｅｒｉｕｍ和Ａｒｔｈｒｏｂａｃｔｅｒ ｓｐ．未表现出较强的释放能力。     

锕系、镧系元素分离中新萃取剂的研究(Ⅱ) --HCBMPPT对铀(Ⅵ)的萃取机理研究

研究了4-(邻氯苯甲酰基)-2,4-二氢-5-甲基-2-苯基-3H-吡唑硫酮-3(HCBMPPT)在硝酸介质中对铀(Ⅵ)的萃取行为,并对萃取配合物的化学组成及萃取机理进行了分析和讨论.实验结果表明,其萃取分配比随萃取剂浓度及pH值的升高而增大.     

Synergistic extraction and separation of Am(III) and Ln(III) with HBMPPT-sulfoxide-HNO3-toluene system

1 INTRODUCTIONAmericiuxn is a typical transuredum element. The Chemical properties of Am(lll)are similar to that Of trivalent lanthanides, Ln(lll). The separation of Am(lll) froman(lll) represents one of the most difficult and twortant ploblems in the separationscien..[1-7]. Actinides (ill) overlap in size with Ln(lll) and thus two groups have sedlaxcharge-to-radius ratios. Choppin[61 considered that Am(lll) and Ln(lll) both ethbit"hard acid" Character and their interaction in solutio…     

Effect on non-linear soil-structure interaction due to base slab uplift on the seismic response of a high-temperature gas-cooled reactor (HTGR)

In high seismic regions it has often been the practice to use oversized base slabs for the major nuclear power plant structures in order to prevent, or at least minimize, the amount of dynamic base slab uplift which will result from the overturning moments developed during seismic ground motion. Two major reasons have been expressed as to why dynamic base slab uplift should be minimized: (1) As nuclear power plants are normally designed for seismic loadings based upon linear analysis, and since soil-structure interaction becomes nonlinear when only a portion of the base slab is in contact with the soil, linear elastic analysis may be unacceptable if base slab uplift occurs (as the resultant design loads may be incorrect), and (2) substantial uplift could cause excessive toe pressures in the supporting soil and significant impact forces when the slab recontacts the soil.The primary purpose of this paper is to evaluate the importance of the nonlinear soil-structure interaction effects resulting from substantial base slab uplift occurring during a seismic excitation. The structure considered for this investigation consisted of the containment building and prestressed concrete reactor vessel (PCRV) for a typical HTGR plant. A simplified dynamic mathematical model was utilized consisting of a conventional lumped mass structure with soil-structure interaction accounted for by translational and rotational springs whose properties are determined by elastic half space theory. Three different site soil conditions (a rock site, a moderately stiff soil, and a soft soil site) and two levels of horizontal ground motion (0.3 and 0.5 g earthquakes) were considered.Based upon the parametric cases analyzed in this investigation, it may be concluded that linear analysis (which ignores the nonlinear soil-structure interaction effects of base slab uplift) can be used to conservatively estimate the important behavior of the base slab even under conditions of substantial base slab uplift. For all cases investigated here, linear analysis resulted in higher base overturning moments, greater toe pressures, and greater heel uplift distances than nonlinear analyses. It may also be concluded that the nonlinear effect of uplift does not result in any significant lengthening of the fundamental period of the structure. Also, except in the short period region (period less than half of the fundamental period) only negligible differences exist between in-structure response spectra based on linear analysis and those based on nonlinear analysis.Finally, it may be concluded that for sites in which soil-structure interaction is not significant, as for the rock site, the peak structural response (shears and moments) at all locations above the base mat are not significantly influenced by the nonlinear effects of base slab uplift. However, for the two soil sites the peak shears and moments are, in a few instances, significantly different between linear and nonlinear analyses. As a result, linear analysis may be used to determine all structural response for rock sites even when there is substantial base slab uplift. However, for soil sites, nonlinear analyses are necessary if substantial base slab uplift occurs.     

Centrifuge modelling of seismic soil structure interaction effects

Proper understanding of the role of unbounded soil in the evaluation of dynamic soil structure interaction (SSI) problem is very important for structures used in the nuclear industry. In this paper, the results from a series of dynamic centrifuge tests are reported. These tests were performed on different types of soil stratifications supporting a rigid containment structure. Test results indicate that accelerations transmitted to the structure's base are dependent on the stiffness degradation in the supporting soil. Steady build up of excess pore pressure leads to softening of the soil, which decreases the shear modulus and shear strength and subsequently changes the dynamic responses. It is also shown that the presence of the structure reduces the translational component of the input base motion and induces rocking of the structure. The test results are compared with some standard formulae used for evaluating interaction in the various building codes. It was concluded that the dynamic shear modulus values used should be representative of the site conditions and can vary dramatically due to softening. Damping values used are still very uncertain and contain many factors, which cannot be accounted in the experiments. It is emphasized that simplified design processes are important to gain an insight into the behaviour of the physical mechanism but for a complete understanding of the SSI effects sophisticated methods are necessary to account for non-linear behaviour of the soil material.     

镤在无机吸附剂上的吸附行为及它与铀、钍的分离

~(233)Pa是中子辐照钍制取核燃料~(233)U的重要中间体。长期以来人们认为用无机吸附剂来分离、纯化~(233)Pa是行之有效的方法。我们利用在高通量堆中辐照的钍经阴离子交换法分离获得的~(233)Pa、~(233)U以及天然Th,研究了在HNO_3介质中,~(233)Pa、~(233)U及Th在硅胶、SnO_2、Sb_2O_5及MnO_2四种无机吸附剂上的吸附行为,其中SnO_2与Sb_2O_5是前人没有作过系统研究的。通过单管平衡实验,我们找到了~(233)Pa吸附及解吸的合适条件,并由柱实验证明,~(233)Pa可以从U、Th中获得较好的纯化。从柱实验效果看,硅胶与SnO_2都有良好的性能,但在实际使用中,SnO_2比之硅胶似乎更为理想,因此我们认为SnO_2有可能成为分离、纯化~(233)Pa的一种有效吸附剂。     

鉴别新核素^202Pt的化学分离方法的研究

提出了一个从大量汞和其它干扰元素中分离痕量铂的化学分离程序,且已成功地用于新核素~(202)Pt的鉴别。照射后的氧化汞靶溶于浓盐酸中,用乙醚多次萃取除去干扰元素铊,在萃取后的水相中加入饱和氯化铵溶液,用氯铂酸为载体,以氯铂酸铵沉淀载带核反应产生的痕量铂。分离过程中汞、金、铊的去污因子及铂的回收率均获得了令人满意的结果。     

Application of N,N-di(2-ethylhexyl)butanamide for mutual separation of U(VI) and Pu(IV) by continuous counter-current extraction with mixer-settler extractors

Continuous counter-current extraction using N,N-di(2-ethylhexyl)butanamide (DEHBA) as an extractant was performed with mixer-settler type extractors consisting of U–Pu extraction, scrub, U recovery, Pu back-extraction, and U back-extraction steps. The feed solution used in the continuous counter-current extraction was 3 mol/dm³ (M) nitric acid containing U, Pu, and simulated fission products of Sr, Ba, Zr, Mo, Ru, Rh, Pd, and Nd. More than 99.9% of U and Pu in the feed was extracted by 1.9 M DEHBA at the U–Pu extraction step with negligible extraction of Sr, Ba, Mo, Ru, Rh, and Nd. The extracted Pu was back-extracted via contact with 0.3 M nitric acid in the Pu back-extraction step, and the ratio of Pu distributed to the Pu fraction stream was ～ 82%. It was confirmed that 1.9 M DEHBA effectively recovered U in the U recovery step, and the ratio of U in the Pu fraction stream was less than 1%. The extracted U was back-extracted in the U back-extraction step, and more than 98% of U was recovered in the U fraction stream.     

Method for determining the separation velocity (vs) of extraction emulsions

Translated from Atomnaya Énergiya, Vol. 65, No. 4, pp. 268–272, October, 1988.     

Image charge interaction of multicharged ions in grazing collisions with an Al(111)-surface

We study the angular distributions of multicharged noble gas ions after scattering from a clean and a cesiated Al(111)-surface under a grazing angle of incidence. The data show pronounced effects of the image charge attraction on the incident trajectory which allow us to deduce the energy gained by the projectile during the approach towards the surface. We present a detailed discussion of our experimental method and compare the results with an “over-barrier model” describing the neutralization of multicharged ions in front of a metal surface.     

60MeV/u~(18)O离子同天然铀反应钍的放化分离

用１－苯基－３－甲基－４－苯甲酰基吡唑啉酮－５（ＰＭＢＰ）作萃取剂,２３４Ｔｈ为示踪剂,对在ＨＮＯ３介质中用ＰＭＢＰ－苯萃取钍的条件实验进行了研究。在条件实验的基础上提出了一个从中能１８Ｏ离子照过的天然铀样品中简便、快速地分离钍的化学流程。钍样品的Ｙ射线谱显示该流程能去除绝大多数产物元素,特别是Ｕ、Ｃｅ和Ｉ的沾污。