A novel approach to develop the control of Telbot using ANFIS for nuclear hotcells

This paper develops an improved controller for Telbot. Telbot is a new 6 DOF tele-robot, with special kinematic design, famous for working in nuclear hotcells. The recent controllers are based on simple and improved PID controllers, with visible tracking error. In this project, an ANFIS controller was designed and trained for controlling this tele-robot. The proposed controller generates an appropriate torque for reaching desired state, without any error. The controller was initialized with if-then rules. The training includes online and offline processes. The offline processes have light loads, and prepaid more than 90% of system desired, but the online processes do the last critical 10%, and remove all the errors. The controller is describing the high degree of nonlinear dynamics behavior of the Telbot. The final simulation shows the error-less tracking.     

A novel testing approach for SSRF digital power supply controllers

Digital power supply controller is one of the key parts of SSRF high resolution high stability magnet power supply system.It is very essential to keep any degradation of these excellent properties by any stages as small as possible via careful testing when the controller is developed.In this study,a novel testing approach was presented,with which a novel closed conrail loop without actual power converter was constructed,and the new developed SSRF Digital Controller can work well in it.     

131I在镀钯银丝上的吸附工艺研究

碘-125吸附在银丝上作为源芯,封装在肽管中,即为种子源,目前广泛用于治疗眼内和脑内的肿瘤,并用于前列腺癌的永久性植入治疗。本工作用131I替代125I考察了不同浓度、不同体积的PdCl2对银丝进行处理后对吸附的影响;探索了吸附液体积、温度、时间以及载体量等条件的变化对吸附的影响,确定了碘在银丝上的吸附工艺,吸附率达90%以上。     

A thin film approach to protein crystallography

A novel approach for the investigation of proteins or macromolecules is outlined in this conceptual study. The preparation of grapho-epitaxial layers on nanotemplated substrates is proposed as an alternative to the preparation of single crystals by vapour diffusion techniques. Crystal structure investigations of such layers may then be performed via grazing-incidence diffraction (GIXRD) in the Laue mode. Quantitative expressions for the position and intensities of XRD peaks in this geometry are presented that fully consider the effects of refraction and absorption. A simulation of the Laue-GIXRD pattern of single-crystalline layers of Concanavalin A is given. The main challenges of the approach are concluded to relate to the preparation of single-crystalline protein layers. However, if those obstacles could be overcome, a 10–100-fold faster sample throughput would become possible.     

A consistent approach to severe accident management

The approach adopted for severe accident management (SAM) at the Loviisa nuclear power plant (in Finland) is presented and discussed. The approach includes a number of significant hardware changes and procedures that allow lowering of the lower head thermal insulation and neutron shield assembly, opening of the ice condenser doors, and spraying (externally) of the steel shell of the containment. It is expected that with these changes we can assure in-vessel debris coolability and retention, gradual burning of the hydrogen with good access to the ice condenser, and long term stabilization of the containment pressure, even in the absence of the residual heat removal system. Methodological aspects of demonstrating these SAM objectives, and the status of work in support of related quantifications (of key phenomena), are included in sufficient detail to provide an integrated perspective of the approach taken. The detailed quantifications, separately on each task, will follow, as respective research and quantification programs come to completion.     

A modular approach to lead-cooled reactors modelling

After an overview of the lego plant simulation tools (LegoPST), the paper gives some details about the ongoing LegoPST extension for modelling lead fast reactor plants. It refers to a simple mathematical model of the liquid lead channel dynamic process and shows the preliminary results of its application in dynamic simulation of the BREST 300 liquid lead steam generator. Steady state results agree with reference data [IAEA-TECDOC 1531, Fast Reactor Database, 2006 Update] both for water and lead.     

A reliability program approach to operational safety

A Reliability Program (RP) model based on proven reliability techniques is being formulated for potential application in the nuclear power industry. Methods employed under NASA and military direction, commercial airline and related FAA programs were surveyed and a review of current nuclear risk-dominant issues conducted. The need for a reliability approach to address dependent system failures, operating and emergency procedures and human performance, and develop a plant-specific performance data base for safety decision making is demonstrated.Current research has concentrated on developing a Reliability Program approach for the operating phase of a nuclear plant's lifecycle. The approach incorporates performance monitoring and evaluation activities with dedicated tasks that integrate these activities with operation, surveillance, and maintenance of the plant. The detection, root-cause evaluation and before-the-fact correction of incipient or actual systems failures as a mechanism for maintaining plant safety is a major objective of the Reliability Program.Embodied within the approach are (1) determination of acceptable safety system performance criteria and associated alert levels: (2) tracing and/or trending of in-plant and industry systems performance and management of the associated surveillance, maintenance, and reportable event data base; (3) determination of risk-importance prioritized systems, components, and root-causes and ad hoc response to inplant safety problems or potentially applicable industry problems identified by NRC or INPO; and (4) a closed-loop failure reporting and corrective action program for correcting performance criteria violations or identified problems either through changes in operation or maintenance or through changes in utility management practices.     

A new approach to automatic radiation spectrum analysis

The application of adaptive methods to the solution of the automatic radioisotope identification problem using the energy spectrum is described. The identification is carried out by means of neural networks, which allow the use of relatively reduced computational structures, while keeping high pattern recognition capability. In this context, it has been found that one of these simple structures, once adequately trained, is quite suitable to identify a given isotope present in a mixture of elements as well as the relative proportions of each identified substance. Preliminary results are presented, and are deemed good enough to consider these adaptive structures as powerful and simple tools in the automatic spectrum analysis     

A new approach to energy-dependent neutron transport theory

A new approach to energy-dependent neutron transport theory is described which treats the asymptotic solution of the Boltzmann equation exactly and approximates the spatial transient by the separable kernel model.The method is illustrated by an application to the Milne and pulsed neutron problems, and exact expressions are obtained for the extrapolated endpoint and the emergent angular distribution.It is pointed out that the method can be extended to include criticality problems and three-dimensional geometries.     

A statistical approach to fuel densification during sintering

Densification during isothermal sintering has been analyzed by considering the pore size distribution functions of log-normal type. The influence of statistical parameters (mean and standard deviation) on the densification kinetics and pore spectra shift has been identified.     

A new computational approach to nuclear aerosol problems

The nonlinear kinetic aerosol equation, describing the time evolution of an aerosol distribution within a well-stirred container, is formulated in a mathematically “conservative” form. A numerical method is then developed for which conservation of mass is automatically satisfied. This procedure simplifies the derivation of conservative numerical schemes by reducing the number of approximations that must be made. Comparisons between an exact solution of the kinetic aerosol equation and numerical approximations show the following: numerical solutions based on the conservative form of the kinetic equation are more accurate and are obtained more efficiently than numerical solutions based on the standard “nonconservative” form of the kinetic equation.     

A systematic approach to the radiation damage problem

To assess the suitability of a material for use as a core component in a fast reactor or for the first wall in a fusion reactor, it is necessary to know the irradiation damage behaviour of the material outside the usual materials testing data domain. In the present paper we propose a strategy based on a closely co-ordinated programme of experimental and theoretical research. The aim of this strategy is the systematic construction of a physically based model of the evolving damage structures. This would then allow both the necessary extrapolations of the data to the desired conditions to be achieved in a reliable fashion and provide a rational basis for the development of low-swelling alloys for the two nuclear systems.     

A correlation of rewetting data

Following a loss-of-coolant accident in a water reactor the fuel pins dry out and overheat and it becomes necessary to rewet them to restore normal temperatures. A thermal conduction analysis of rewetting is presented in which it is shown that the heat transfer coefficient associated with rewetting may be taken as an arbitrary function of surface temperature, rather than a constant, without changing the dependency of rewetting velocity on the other variables. An effective heat transfer coefficient then replaces the constant value used in previous expressions for the rewetting velocity. Experiments at atmospheric pressure show that the rewetting rate increases with inlet water subcooling. The available rewetting data at both atmospheric and elevated pressure have been analysed using an existing theoretical model. Taking the effective heat transfer coefficient as proportional to the product of mass flow rate and inlet subcooling a data fit has been achieved to within a factor of two. Expressions are given which predict rewetting rates for a wide range of pressures, wall temperatures, subcoolings, clad materials and geometries.     

A new approach to plasma profile control in ITER

Advanced tokamak operation in ITER, such as the steady-state and hybrid modes, requires an active real-time feedback control of plasma profiles to achieve the advanced regimes for sustained operation. In this work, we have explored a potentially robust control technique that simplifies the active real-time control of electron temperature and safety factor profiles in ITER. As a new and simple approach, static responses of the plasma profiles to power changes of auxiliary heating and current drive are modelled and updated in real-time, differing from the techniques which use a dynamic model deduced from identification experiments, or even a simplified explicit model. To allow real-time update of the plasma profile response model, the underlying physics is simplified with several assumptions. The electron temperature profile response is modelled by simplifying the electron heat transport equation. The safety factor profile response is modelled by directly relating it to the changes of source current density profiles. The required actuator power changes are calculated using the singular value decomposition technique, taking the saturation of the actuator powers into account. The potential of this control technique has been tested by applying it to simulations of the ITER hybrid mode operation using CRONOS. In these simulations, the electron temperature and safety factor profiles were well controlled either independently or simultaneously.     

A new approach to designing reduced scale thermal-hydraulic experiments

Reduced scale experiments are often employed in engineering because they are much cheaper than real scale testing. Unfortunately, though, it is difficult to design a thermal-hydraulic circuit or equipment in reduced scale capable of reproducing, both accurately and simultaneously, all the physical phenomena that occur in real scale and operating conditions. This paper presents a methodology to designing thermal-hydraulic experiments in reduced scale based on setting up a constrained optimization problem that is solved using genetic algorithms (GAs). In order to demonstrate the application of the methodology proposed, we performed some investigations in the design of a heater aimed to simulate the transport of heat and momentum in the core of a pressurized water reactor (PWR) at 100% of nominal power and non-accident operating conditions. The results obtained show that the proposed methodology is a promising approach for designing reduced scale experiments.     

A novel way to study the nuclear collective excitations

Typically,the unambiguous determination of the quantum numbers of nuclear states is a challenging task.Recently,it has been proposed to utilize to this aim vortex photons in the MeV energy region and,potentially,this could revolution-ize nuclear spectroscopy because of the new and enhanced selectivity of this probe.Moreover,nuclei may become diag-nostic tools for vortex photons.Still,some open questions have to be dealt with.