Criticality Safety Benchmark Experiment on 10% Enriched Uranyl Nitrate Solution Using a 28-cm-Thickness Slab Core

The second series of critical experiments with 10% enriched uranyl nitrate solution using a 28-cm-thick slab core have been performed with the Static Experiment Critical Facility of the Japan Atomic Energy Research Institute. Systematic critical data were obtained by changing the uranium concentration of the fuel solution from 464 to 300 gU/l under various reflector conditions. In this paper, the thirteen critical configurations for water-reflected cores and un reflected cores are identified and evaluated. The effects of uncertainties in the experimental data on k ^eff are quantified by sensitivity studies. Benchmark model specifications that are necessary to construct a calculational model are given. The uncertainties of k _eff's included in the benchmark model specifications are approximately 0.1%δk _eff. The thirteen critical configurations are judged to be acceptable benchmark data. Using the benchmark model specifications, sample calculation results are provided with several sets of standard codes and cross section data.     

Calculation of Azimuthally Dependent Thermal-Neutron Albedos for Slab by Method of Invariant Embedding

The method of invariant embedding has been applied to the calculation of differential thermal-neutron albedos for a semi-infinite ordinary concrete slab. The calculations have been performed in both cases of isotropic and anisotropic scattering in the laboratory system.

The calculated albedo data are compared with those obtained by the experiments and the semi-empirical formula fitted the detailed data obtained by Monte Carlo method. The calculated results assuming isotropic scattering are in good overall agreement with the values obtained by Monte Carlo and S_N methods, but there are some errors for azimuthally anisotropic scattering when azimuthal angle becomes large.

In this method, much less computing times within given accuracy are required for azimuthally isotropic scattering, but it is pronounced that the necessary computing times are heavily dependent on N in DP _(N/2)-1 (ξ)T_N(μ) quadrature sets when the azimuthally anisotropic scattering is considered.

It is found that, except for large N for the case of azimuthally anisotropic scattering, the calculation of differential albedo data by using invariant embedding method is much faster than those by using the Monte Carlo and the discrete ordinates methods.     

基于抛物线形库仑-莫尔准则的钢筋混凝土板抗冲切承载力

在刚塑性冲切计算模型的基础上,采用二次抛物线形库仑 莫尔混凝土强度准则,运用虚功原理,建立考虑混凝土板中抗弯钢筋销栓作用的冲切承载力计算式。根据已有板冲切试验研究成果,如冲切角和破坏时刻抗弯钢筋应力等数据,对板冲切承载力计算式进行简化,给出简化计算式。与国内外混凝土板冲切试验数据进行计算比较后发现,简化计算式的计算结果较好地符合实测承载力;抗弯钢筋的销栓作用约占钢筋混凝土板总冲切承载力的6%～11%,而忽略抗弯钢筋的销栓作用会给计算结果带来较大影响。     

Failure Resistance of Historic Stone Bridge Structure of Charles Bridge. II: Susceptibility to Floods

The paper is a follow-up to the first part devoted to an analogical problem investigated with a view to the degradation of the stone structure due to the effects of nonstress load, and it deals with the probability problem of the bridge structure collapse under the effect of an extreme flood wave. The paper presents the results of the numerical analysis of the response of the historic stone bridge structure of Charles Bridge of the 14th century to the flood wave effect simulated by angular rotation, subsidence, and shifting in the footing bottom of a bridge pier. Special focus is on the effect of interventions into the stone bridge structure dating back to the last major overhaul of 1967–1975, particularly, on the effect of the reinforced concrete slab (tie plate) connecting the opposite bridge breast walls increasing the rigidity of the breast walls and their structurally efficient connection to the vaults of the bridge arches. The numerical analyses performed point out the prevailing negative effects of the implemented interventions in terms of structural rigidity of the stone bridge structure exposed to the effect of a flood wave.     

Mixing and Oxide Cleanness in Sequence Casting of Heats of Differing Compositions

For a two‐strand slab caster and a tundish capacity of 50 t the transition zone between two heats of different chemical composition was experimentally defined. The distribution of various elements was measured. The transition curves also show the penetration depth of the casting stream using a bifurcated submerged nozzle. This is basic information for the calculation of the mixing zone. Knowledge of the permissible composition ranges permits optimisation of the usable length of the strand. The impact of ladle change on oxide cleanness is analysed as well.     

利用石棉尾矿制造微晶玻璃装饰板的研究

似石棉尾矿为主要原料，经熔制、成型、热处理和磨光等工序制造的微晶玻璃装饰板，尾矿掺量可高达60％，产品物理化学性能指标优于天然大理石和花岗石。本方法工艺简单，参数合理，生产条件成熟，是石棉尾矿开发利用的一条有效新途径。本文主要探索了它的配方和熔制、成型及热处理制度。     

GFRP筋混凝土桥面板剪切承载力理论算法研究

采用玻璃纤维复合筋(GFRP Bar)材代替钢筋能够有效解决传统钢筋混凝土桥面结构由于钢筋锈蚀所引起的结构功能退化问题。过去试验研究表明在FRP筋混凝土桥面承受集中荷载作用下,冲切破坏模式是一种常见的破坏模式。本次研究采用现有规范及已经发表抗冲切承载力计算模型对多组混凝土桥面板试验结果进行冲切承载力预测。通过与试验结果对比发现,由于大多数理论模型是基于简支构件试验结果建立的经验公式,其无法准确计算FRP筋混凝土桥面结构的冲切承载力。笔者前期建立的GFRP筋混凝土桥面板承载力理论方法考虑了拱效应的作用,计算结果与试验结果有较好的吻合。理论分析中发现,由于较高配筋率和较小跨高比,大部分GFRP筋混凝土桥面板发生剪切破坏而非弯切破坏。因此本文建立了简化的GFRP筋混凝土板剪切承载力计算方法,该模型计算结果与多个试验结果吻合良好。     

Design of Monolithic Concrete Ground Floors

It is known that the slabs on soil constitute one of the most difficult types of structures despite their apparent simplicity. The objective of this paper is to give a general survey of the design of ground supported slabs with the interposition of a suitable subbase. A solution is proposed with the following characteristics： （1） complete suppression of joints; （2） conventional reinforcement with meshes in the upper and lower fiber of the slab in order to confront and distribute cracking that is caused by hindrance of free contractions and expansions; （3） effective confrontation of problems of bulging. The proposal is in effect on one hand for industrial floorings and on the other hand for concrete pavings with large durability requirement.     

A Comparative Study on the Flexural Behaviour of Waffle and Solid Slab Models When Subjected to Point Load

The determinations of flexural behavior of some engineering structures are based on different theories and equations, but it has been observed that some of these equations may not give true representation. This work has looked into the difference that may occur between theoretical and experimental results. An experimental test carried out on models of waffle and solid slabs structures were described and results from twenty test samples are presented. Each specimen was subjected to an incremental axial loading of 1 kN interval after 28 days of casting. The flexural moments, deflections and crack width at failure were obtained. The experimental flexural crack and theoretical flexural cracks for both types of slabs were compared. The result for flexural moments for waffle was 5.526 kNm, while solid slab was 3.684 kNm. The deflections showed that waffle slabs has 3.64 mm while solid has 9.28 mm, hence waffle has a higher structural stiffness than solid slabs, but the flexural cracks did not give the same results especially for the estimated crack width. It was concluded that estimated results based on developed equations may not be accurate because it is based on ideal situation.     

Use of impulse radar as a method for the non‐destructive testing of concrete slabs

The paper shows that Impulse Radar provides engineers and associated professions with an invaluable non‐destructive testing tool and when used in conjunction with other methods of testing, Impulse Radar has an important role to play throughout the complete lifecycle of a structure.