Javier Dies

Importance of Electron Cyclotron Wave Energy Transport in ITER

The importance of electron cyclotron (EC) wave emission to the local electron power balance is analysed for various ITER operation regimes and, for comparison, for typical working conditions of FIRE, IGNITOR and the reactor-grade ITER concept as considered during the Engineering Design Phase (ITER-EDA). To cover the non-local effects in EC wave emission as well, the CYTRAN routine along with the ASTRA transport code is used. As a result, EC wave emission is shown to be a significant contributor to core electron cooling if the core electron temperature is about 35 keV or higher, as expected for ITER and tokamak reactor steady-state operation; in fact, it becomes the dominant core electron cooling mechanism at temperatures exceeding 40 keV, as such affecting the core plasma power balance in an important way.

Software and hardware developments for remote participation in TJ-II operation. Proof of concept using the NPA diagnostic

The operation protocols for the TJ-II require that all diagnostics be controlled remotely during machine operation. For this reason, most diagnostics have control systems that permit remote actions to be performed on their various subsystems. An Internet browser, which connects to a server where the human machine interfaces (HMIs) for all diagnostics are situated, is used for this. Real time control has been resolved using programmable automates for each diagnostic. Dedicated application software is in operation to provide a user interface for programming digitisers, for signal visualisation and for data processing during TJ-II discharges. This software is an event-based application that can be remotely launched from any X terminal. Other resources provided to users are graphical and computational tools for data analysis, data compression, off-line access to databases, reception of data and its integration in the databases at any moment. Two neutral particle analysers (NPAs) are operating on TJ-II to measure the energy spectra of charge exchange (CX) neutral particles. Protocols require remote control over several actions and subsystems of this diagnostic. With all these tools a proof of the concept of remote participation has being performed during the present experimental campaign. The NPA diagnostic has been operated from UPC-ETSEIB in Barcelona, 600 km of distance from the machine.

Energy-Resolved Neutral Particle Fluxes in TJ-II ECRH Plasmas

Abstract Energy-resolved neutral particle fluxes are studied in the TJ-II stellarator by using measurements from a neutral particle analyzer. The average ion energy can be deduced up to positions outside the last closed magnetic surface because of an upgrade of the diagnostic. The results suggest that the average ion energy profile is flat, even at positions outside the last closed magnetic surface, which implies the existence of hot ions well outside the plasma. Such a flat profile may be related to wide ion orbits connecting distant areas of the plasma.

Upgrading of Plasma Wall Interaction Model for Tokamak Transient Modeling Code AINA 2.0, Used in Safety Studies of ITER Plasma Instability Events

Abstract In this contribution, an upgraded model for plasma-wall interaction in the AINA code is presented. The AINA code is a comprehensive hybrid code comprising a global balance plasma dynamics model and a radial and poloidal thermal analysis of in-vessel components. AINA is an evolution of the SAFALY code, which was initially adopted to assess ITER EDA plasma safety events and quantitatively investigate plasma instability events in nuclear fusion reactors such as ITER. The new erosion code module includes algorithms for the most relevant plasma wall interaction phenomena that will take place in the ITER vessel during the steady state of the normal operation. Physical sputtering, radiation enhanced sublimation (RES), and chemical erosion algorithms have been added to the previous thermal sublimation algorithm. The erosion results from these models have been benchmarked with results for ITER normal operation from the B2-Eirene code. The new erosion model had to be tested with external data for particle fluxes over the wall, because the AINA code does not presently have the ability to model those particle fluxes. However, with the new results, the impurity transport model parameters have been re-calibrated and some useful conclusions have been extracted.

Electron heat transport comparison in the Large Helical Device and TJ-II

The electron heat transport in the Large Helical Device (LHD) [K. Ida, T. Shimozuma, H. Funaba et al., Phys. Rev. Lett. 91, 085003 (2003)] and TJ-II [F. Castejon, V. Tribaldos, I. Garcia-Cortes, E. de la Luna, J. Herranz, I. Pastor, T. Estrada, and TJ-II Team, Nucl. Fusion 42, 271 (2002)] is analyzed by means of the TOTAL [K. Yamazaki and T. Amano, Nucl. Fusion 32, 4 (1992)] and PRETOR-Stellarator [J. Dies, F. Castejon, J. M. Fontdecaba, J. Fontanet, J. Izquierdo, G. Cortes, and C. Alejaldre, Proceedings of the 29th European Physical Society Conference on Plasma Physics and Controlled Fusion, Montreux, 2002, Europhysics Conference Abstracts, 2004, Vol. 26B, P-5.027] plasma simulation codes and assuming a global transport model mixing GyroBohm-like drift wave model and other drift wave model with shorter wavelength. The stabilization of the GyroBohm-like model by the E×B shear has been also taken into account. Results show how such kind of electron heat transport can simulate experimental evidence in both ...

Fusion Neutron Source Model for the Systems Analysis of a Tokamak Power Plant

Abstract In this work, a model has been developed to calculate the neutron wall loading poloidal distribution in a generic tokamak plasma and vessel geometry on the basis of Monte Carlo simulation. Different neutron source radial profiles corresponding to advanced plasma scenarios have been implemented in this model, using combinations of step and parabolic functions. The model has been validated with data from state-of-the-art simulations of ITER wall loading, and a parametric study has been performed over different plasma geometries and radial profiles to check the variability of the neutron poloidal profile. The results show the effect of the different configurations on neutron wall loading. This model can be used for parametric studies for conceptual design or systems analysis activities.

Internal transport barrier simulation and analysis in LHD

In order to study the electron heat transport channel and to clarify the electron thermal diffusivity dependence with some plasma parameters in large helical device (LHD) shots with electron internal transport barrier (eITB), some transport models have been added to the TOTAL code. These models can be divided into two categories: GyroBohm-like drift wave model and other drift wave models with shorter wavelength. A new model consisting of a mix of both models has also been derived for this study as a good candidate for explaining the eITB. The effect of anomalous transport reduction by the electric field shear has been introduced by means of the factor (1 + (τf E×B ) γ ) -1 . This factor has been previously checked as a good candidate to suppress anomalous transport in tokamak plasmas. Results show that a combination of the GyroBohm-like model and the drift wave model with shorter wavelength together with the electric field shear can explain the transition between non-eITB and eITB shots. The central temperature dependence with density is also well simulated. In the case of GyroBohm models, they also fit temperature profiles, although central temperature dependence with density is higher.

Development and assessment of fire-related risk unavailability matrices to support the application of the maintenance rule in a PWR nuclear power plant

ABSTRACT Two methods are presented which serve to incorporate the fire-related risk into the current practices in nuclear power plants with respect to the assessment of configurations. The development of these methods is restricted to the compulsory use of fire probabilistic safety assessment (PSA) models. The first method is a fire protection systems and key safety functions unavailability matrix which is developed to identify structures, systems, and components significant for fire-related risk. The second method is a fire zones and key safety functions (KSFs) fire risk matrix which is useful to identify fire zones which are candidates for risk management actions. Specific selection and quantification methodologies have been developed to obtain the matrices. The Monte Carlo method has been used to assess the uncertainty of the unavailability matrix. The analysis shows that the uncertainty is sufficiently bounded. The significant fire-related risk is localized in six KSF representative components and one fire protection system which should be included in the maintenance rule. The unavailability of fire protection systems does not significantly affect the risk. The fire risk matrix identifies the fire zones that contribute the most to the fire-related risk. These zones belong to the control building and electric penetrations building.

A new code for spectrometric analysis for environmental radiological surveillance on monitors focused on gamma radioactivity on aerosols

This paper presents a new code for the analysis of gamma spectra generated by an equipment for continuous measurement and identification of gamma radioactivity in aerosols with paper filter. It is called pGamma and has been developed by the NERG group at the Technical University of Catalonia - Barcelona Tech and Raditel Serveis i Subministraments Tec-nològics, Ltd. The code is being adapted to the monitors of the Environmental Radiological Surveillance Network of the Gener-alitat de Catalunya (local Catalan Government), Spain. The code is a spectrum analysis system for identifying and determining activity concentration of gamma emitters. It generates alarms depending on the activity of emitters and then elaborates reports. Moreover, it includes a library with NORM and artificial emitters of interest. The code is being used at three stations of the Network equipped with an aerosol monitor (Ascó and Vandellòs (province of Tarragona)and Barcelona).

Equipment for the Continuous Measurement and Identification of Gamma Radioactivity on Aerosols

This paper describes an equipment for continuous measurement and identification of gamma radioactivity in aerosols developed by the Nuclear Engineering Research Group (NERG) at the Technical University of Catalonia (UPC) and Raditel Serveis i Subministraments Tecnològics, Ltd. A spectrometric analysis code has been specially designed for it. Spectrum analysis identifies and determines activity concentration of aerosol emitters captured by a fiberglass paper filter. This new equipment is currently operating in three radioactivity monitoring stations of the Environmental Radiological Surveillance Network of the Generalitat of Catalunya (local Catalan government): two near Ascó and Vandellòs Nuclear Power Plants in the province of Tarragona and one in the city of Barcelona. Two more monitors are expected to be deployed at Roses (province of Girona) and Puigcerdà (province of Barcelona). Measurements and evolution analysis results of emitters identified at these stations were also provided.