Two-tanks heat storage for variable electricity production in SFR: preliminary architecture and transient results

International audienceThe prospective energy mix scenarii generally imply a large contribution of renewable energy. The increasing use of solar and wind energies, which are intrinsically intermittent, actually constitutes a source of uncertain-ties and fragilities for the electrical grid. As nuclear energy produces heat before being converted into elec-tricity, a step of heat storage prior to the heat conversion step might be effective to remedy this intermittence in order to ensure the grid reliability and flexibility without involving large variations of the nuclear core power. Depending on the daily scenarii, the nuclear core could even stay at its maximal power all day long. Following this approach, a smaller core is then able to cope with the same peaks of demand than a larger one without heat storage systems.In this paper, a preliminary heat storage architecture coupled to a Sodium Fast Reactor is proposed in order to highlight the benefits of such a storage technology. The technical design based on two tanks respectively containing hot and cold fluids is inspired by current solar power technologies. The sizing of this system is carried out with a Thermodynamic Cycle Optimization tool (CYCLOP) and preliminary transients are simulated with the system thermal-hydraulics code CATHARE3. Even if some architecture improvements are still necessary, especially for safety related reasons, this study enables to draw the main benefits of such an electricity production strategy. In particular, it is shown that a variable electricity production while operating the reactor at base load is possible in load following condi-tions, thus enabling to optimize the plant profitability. As the impact on the primary circuit is shown to be negligible in terms of temperature evolutions, thermomechanical loading constraints in the vessel may also be drastically relaxed

Collapse and large signal modelling of GaAs field effect transistors at 77 K

A complete electrical characterization of different types of GaAs field effect transistors at liquid nitrogen temperature is performed. The trapping-detrapping mechanisms on deep levels are particularly adressed and a method is proposed to circumvent the collapse phenomenon which otherwise limits the electrical performances. From these measurements a HEMT non-linear model is extracted and is found efficient for the prediction of the large signal power out versus power in characteristic of a cooled HEMT. A further application could be the optimized design of a cooled low phase noise oscillator

An exhaustive non-linear modelling of GaInP/GaAs HBT's - Application to a low phase noise Ku band VCO

This paper presents an exhaustive non-linear modelling including the low-frequency noise sources which has been implemented to design a low-phase noise voltage controlled oscillator in the Ku band with a 1 GHz bandwidth and a -92 dBc/Hz at 100 kHz carrier offset phase noise level