A survey of the french creep-fatigue design rules for LMFBR

The paper provides a survey of the creep-fatigue design rules for the LMFBR in France. These rules are the ones currently implemented in French component manufacturing. The background of each item is discussed and the trends for improvements currently investigated are described. The cree-fatigue rules apply to elastic analysis only.     

Design improvement of weld design of the reactor internal circulation pump motor casing to the reactor pressure vessel nozzle

The reactor internal recirculation pump (RIP) used in the advanced boiling water reactor (ABWR) design is a glandless wet-motor type pump and is evolved from the pump used in the ABB-A BWRs. On the basis of the proven design viewpoint, the pump nozzle at the bottom head of the ABWR reactor pressure vessel (RPV) to which the RIP is attached is designed as a sleeve-type nozzle as used in the ABB-A BWRs. Several improvements have been made over the ABB-A original nozzle design such as elimination of the weld between the RPV bottom head and nozzle stub (by integral forging) and modification of the weld design (optimization of weld preparation suitable to automatic machine welding and use of insert ring for quality welding). Extensive experimental and analytical studies and the development of machining tools for the penetration bead (the back side of the weld) to inspect the qualification of welding have been performed in Japan with the RIP and the RPV nozzle to confirm the adequacy of the ABWR RIP and the RPV nozzle design.     

RCC-M (rules for design and construction of nuclear components)

The paper deals with a presentation of the design rules included in the French RCC-M code applicable to mechanical components of PWR nuclear islands and published by the French Society for Design and Construction rules for Nuclear Island Components (AFCEN). Particular attention is paid to the major principles which constitute the background of the rules of the code and to recent developments included in the code.     

Elastic creep-fatigue damage evaluation: less restrictive design rules for SNR 2 components

To achieve less conservative design rules for LMFBR Class 1 components in elevated temperatures service, two modifications of the elastic creep-fatigue evaluation in use are proposed: (1) In the creep-damage evaluation, the relaxation of residual stresses during hold-times shall be taken into account; (2) In the fatigue-damage evaluation, the creep effects on the cyclic stress strain hysteresis loop shall be considered by adding the net relaxation strain during holdtimes to the elastic-plastic strain range, and design fatigue curves without hold-time shall apply.     

A design and characteristic experiment of the small annular linear induction electromagnetic pump

A small-scale annular linear induction electromagnetic pump (ALIP) of the externally-supported-in-pipe type with a flowrate of 60 L/min and a developed pressure of 1.3 bar was developed for the circulation of sodium liquid metal. The developed pressure and the efficiency of the pump were analyzed on the change of the pump-design variables by using an equivalent circuit method. The pump designed was manufactured with the consideration to the material and functional requirements of a chemically-active sodium environment. The silicon–iron steel plates with high magnetic permeability and alumina-dispersion-strengthened-copper bands were used as cores and coils of the pump electromagnet for operating in a high temperature. Each turn of the coil was insulated by an asbestos band to protect against an electrical short at a high temperature. Stainless steel compatible with sodium was selected as a structural material. The completed pump was installed in the sodium experimental loop system. At temperatures of 150 °C and 350 °C, the performance of the ALIP (including the P–Q characteristic) was tested by changing the electrical input. The measurements showed that the pumping flowrate and the developed pressure were increased as the input current, voltage and power increased. On the other hand, the developed pressure was decreased with the increase of the flowrate. At the nominal input current and voltage, the developed pressure was 1.25 bar with the relative error of 3.8% compared with the prediction of 1.3 bar at 150 °C, where the flowrate was 54 L/min. The test on the pump showed good agreement with the theoretical calculation with some experimental errors.     

Reactor pressure vessel design and practice

This paper attempts to review the state of the art of methods of analysis and design of the concrete reactor pressure vessels and their components. Existing vessels have been examined for elastic, inelastic and cracking conditions. The results obtained from the analyses given in the appendices are well collaborated with those available from the published experimental tests on models and from site monitoring. The text is provided with an up-to-date comprehensive bibliography. The analytical derivations given in the appendices are based on the authors own research.     

Technical aspects and manufacturing methods for JT-60SA toroidal field coil casings

JT-60SA is a superconducting tokamak machine to be assembled in Naka site, Japan, designed to contribute to the early realization of fusion energy by supporting the exploitation of ITER and research toward DEMO.In the frame of the Broader Approach Agreement a contract between ENEA and Walter Tosto (Chieti, Italy) started on July 2012 for the construction of 18 TF coil casings for JT-60SA. Two different sets of 9 casings each will be progressively delivered, from 2013 to the end of 2015, to ASG Superconductors (Genoa, Italy) and to Alstom (Belfort, France), where the integration of the winding pack into the casing will be carried out.Each TF coil casing (height 7.5 m and width 4.5 m) consists of four main components: one “Straight Leg Outboard” and one “Curved Leg Outboard” both with their own covers, “Straight Leg Inboard” and “Curved Leg Inboard”. The casing components are segmented in forgings and plates made of FM316LNL. The straight leg outboard is composed of two wings welded to a central core and two elbows welded at the ends with a cooling channel installed inside. Elbows of straight leg outboard are segmented in two half-elbows machined from 1 rough forging and welded to the central core made by plate. Welding of wings to the central core is performed in EBW (electron beam welding) and the straight part is welded to the elbows by NGTIG (TIG narrow gap) process. The curved leg outboard is composed of two wings welded to a central core for a final shape of “D”. Other supports are welded by TIG or Electrode process.This paper describes the technical design solutions, the manufacturing methods defined and the particular processes adopted, such as welding (EB, TIG), non-destructive examinations (NDE), vibration stress relief (VSR) and laser tracker survey, most of which have been validated by the construction of two different sets of full scale mock-ups representing the straight and the curved legs.     

Irradiation testing of design models for the GCFR fuel pressure equalization (vent) system

The major consideration in the design of the pressure equalization system for the gas-cooled fast breeder reactor is the release and venting of gaseous and volatile fission products. Single vented rods have been irradiated in the thermal flux of the Oak Ridge Research Reactor (ORR) at GCFR operating conditions of 12–15 kW/ft and 565–685°C cladding outside temperature to determine the fission product release and to verify the design concept. Results obtained to date from measurements of fission gas release and transport have been compared with predictions based on design assumptions to verify analytical models and have established a degree of conservatism of design assumptions.The release of radioactive gases from the fuel matrix was measured directly at 12 kW/ft in an operating fuel rod and was found to be significantly less than the design assumption of 100% instantaneous release and less than predictions using the diffusion model with Findlay's coefficients. Although solid state diffusion was found to be the dominant process delaying the venting of fission gases in the experimental irradiation, fission gas interdiffusion in helium will be the dominant venting transport process for the reactor design. Delay of fission gases by adsorption on charcoal was verified at trap operating temperatures for burn-ups up to 54 000 MWd/t. Volatile fission products (cesium and iodine) did not migrate beyond the fuel-blanket interface. The feasibility of the vented-fuel-rod design concept has been established.     

Reactor pressure vessel design of the high temperature engineering test reactor

The reactor pressure vessel (RPV) of the HTTR is 5.5 m (inside diameter), 13.2 m (inside height), and 122 mm (shell thickness). The RPV contains core components, reactor internals, reactivity control system, etc.2 1/4Cr–1Mo steel is chosen as the material for RPV. The temperature reaches about 400 °C at normal operation. The fluence of the RPV is estimated to be less than 1 × 10¹⁷ n/cm² (E > 1 MeV) and so irradiation embrittlement is negligible, but temper embrittlement is not negligible. For the purpose of reducing embrittlement, content of some elements must be limited in the 2 1/4Cr–1Mo steel for the RPV; embrittlement parameters, J-factor and are used.In this paper, design and structure of the RPV are reviewed first. Fabrication procedure of the RPV and its special feature are described. Material data on the 2 1/4Cr–1Mo steel manufactured for the RPV, especially the embrittlement parameters, J-factor and , and nil-ductility transition temperatures, T_NDT, by drop weight tests, are shown. In-service inspection and results of R&Ds are also described.     

Thermal-hydraulic design of water-cooled pressure tube blanket for a fusion driven subcritical reactor

A Water-cooled Pressure Tube Energy production blanket (WPTE) for fusion driven subcritical reactor has been designed to achieve 3000 MW thermal power with self-sustaining tritium cycle. Pressurized water has great advantages in energy production; however the high pressure may cause some severe structural design issues. This paper proposes a new concept of water-cooled blanket. To solve the problem of the high pressure of the coolant, the pressure tube was adopted in the design and in the meantime, the thickness of the first wall can be significantly reduced as result of adopting pressure tube. The numerically simulating and calculating of temperature, stress distribution and flow analyses were carried out and the feasibility of using water as coolant was discussed. The results demonstrated the engineering feasibility of the water-cooled fusion–fission hybrid reactor blanket module.     

Method for identifying 17-place casings with spent fuel assemblies of AMB reactors at the Beloyarskaya nuclear power plant

A method is proposed for identifying a cylindrical case with a jacket containing 17 spent fuel assemblies from the AMB reactors at the Beloyarskaya nuclear power plant on the basis of measurements of the radiation characteristics in lateral surface of the jacket opposite the fuel assemblies in the outer and inner rows. Computational validation using the PRIZMA and MCNP computer codes is given for the method. It is shown that the collection of signals from detectors is specific to each jacket, and this makes it possible to use it as an identifying indicator. __________ Translated from Atomnaya énergiya, Vol. 102, No. 6, pp. 363–367, June, 2007.     

泵吸式土壤测氡仪气压校正方法的初步研究

泵吸采样过程中,当土壤透气性差时,实际采样到的土壤气进气量将不同程度偏小,引起收集室内气体被扩张,气压降低,影响氡浓度测量结果.根据密闭容积气体特性,可以推导出气压校正系数,校准泵吸式测氡仪进气量难以预计引起的测量误差.为验证校正效果,设计制作了带气压校正器的便携瞬时土壤测氡仪,已获国家专利.两条剖面实验数据表明,校正后氡浓度测量结果更接近理论值,且由进气量原因引起的平均相对偏差高达60%,可用该项校正技术解决.     

Optimum shape design of pressure vessel and nozzle junction

Thick spherical pressure vessels are frequently used in nuclear structural applications. The design of the junction of pipe nozzles and vessels needs careful consideration. In this paper the optimum shape design of the junction is considered. Minimization of the stress concentration factor is considered as the objective function. The junction is completely defined by a set of four curves which in turn depend upon four design variables. The stresses in the junction due to internal pressure are evaluated by finite element analysis using ring-shaped isoparametric elements. Stresses are sampled at a number of selected points along the boundary of the junction. The optimization of the nonlinear programming problem is carried out by an improved move limit method of sequential linear programming. Optimum shapes for internal pressure loading are presented for different transition lengths. The effect of axial load on the nozzle of optimum shapes is studied for a few cases. Detailed discussion of the results is presented.     

海水泵泵轴腐蚀原因分析及对策

通过浸泡试验和电化学试验对泵轴材料3Cr13的耐蚀性进行了研究。结果表明,3Cr13、镀铬层在海水中不耐局部腐蚀;且3Cr13的自腐蚀电位比其他海水泵部件低,易受电偶腐蚀。综合分析认为导致4号海水泵泵轴腐蚀的根本原因在于泵轴材料3Cr13在海水中不耐局部腐蚀,并在装配间隙、电偶效应等条件的驱动以及泥沙的磨损作用下,发生缝隙腐蚀、电偶腐蚀和磨损腐蚀,加速了泵轴基体的腐蚀进程,从而导致泵轴因腐蚀而失效。建议改进密封和选用耐蚀性更好的替换材料。     

Derivation of various non-homogeneous anisotropic shell theories applicable in pressure vessel design

While many shell theories and solutions are available to the designer for conventional pressure-vessel analysis, relatively little work exists for composite material vessels. Such vessels are in general constructed of thin layers consisting of filaments (reinforcing fibers) and matrix materials which may have different thicknesses and different fiber arrangements. Because of this construction, composite vessels must be analyzed according to theories which allow for nonhomogeneous, anisotropic material behavior. These theories are, however, difficult to derive by means of the classical method. A way of departing from the classical assumptions is to apply the method of asymptotic integration of the three-dimensional elasticity equations [1–3]. This method has, as its foundation, the desire to obtain rational two-dimensional theories which are approximately valid when a problem parameter is very small.     

Double-supply-frequency pressure pulsation in annular linear induction pump: Part I: Measurement and numerical analysis

This paper describes an experimental and analytical study of double-supply-frequency pressure pulsation arising in an annular linear induction pump. In a large-scale induction pump, it is known that the supply frequency should be relatively low in order to satisfy a magnetohydrodynamic stability criterion. Under such a low supply frequency, however, double-supply-frequency pressure and flow rate pulsation generated in an induction pump may be of concern. The experimental data obtained in the present work shows that the amplitude of the pressure pulsation increases with decreasing supply frequency, number of poles and/or slip. The numerical result reveals that the pressure pulsation comes from a disturbance of the electromagnetic force near the stator ends.     

Automated design optimization to minimize shearing stress in axisymmetric pressure vessels

The application of a practical design algorithm for optimizing the structural performance of pressure vessels is presented. Specifically, the pressure vessel shape considered is an axisymmetric shell with a torispherical head which is intersected by a nozzle and the criterion for optimization is to minimize the maximum shearing stress occurring in the structure. Both linear and non-linear objective functions describing the shear stress in terms of the design variables are formulated and the system is optimized by using a penalty function procedure combined with a variable metric unconstrained minimization technique. The procedure is illustrated by various examples and is generally applicable as a design tool.