130,713 research outputs found
Parametric analysis of the ITER TF fast discharge using the 4C code
No full textThe recently developed and validated 4C code is used to analyse the fast discharge of an ITER TF coil, including the cooling circuits of winding and casing, and the quench venting system. The analysis shows that a quench can be initiated by the fast discharge, depending on the value of the thermal resistance of the conductor turn insulation. Eddy currents heat the structures and these transfer the heat especially to the side pancakes, where the quench is initiated. The hot spot temperature remains below ~37 K in the winding and 55 K in the structures. The peak pressurization in the winding remains below 8.5 MP
Evaluation of Effective Strain and n-Value of ITER TF Conductor Samples
No full textThe acceptance tests of the Cable in Conduit Conductors for the Toroidal Field coils of the ITER magnet system are being performed at the SULTAN facility in Villigen, Switzerland. The main physical quantity measured in these tests is the current sharing temperature, Tcs . In Tcs measurements, the E-T characteristic curve of the conductor is traced. This curve is utilized here to evaluate the equivalent n-index and the effective strain of the superconducting Nb3Sn cable, under the simplifying assumptions of a uniform strain, current density and temperature distribution in the cable cross section. The variations of n-index and effective strain with mechanical cycling and their sensitivity to the applied transverse load and to the warm up-cooldown process are presented for various conductor samples tested recently
Stability analysis of the ITER CS coil conductors
No full textThe stability analysis of the International Thermonuclear Experimental Reactor (ITER) Central Solenoid (CS) coil Nb3Sn conductor is performed following a similar approach to that recently used for the ITER Toroidal Field and Poloidal Field conductors. The most critical conductors in the winding pack, as well as the most critical (minimum temperature margin) location along them, are identified by the application of the Vincenta code, which also provides the initial and boundary conditions in the reference case. The Mithrandir code is then applied to these conductors, using a much finer grid than affordable in the Vincenta analysis, in order to capture the details of normal zone initiation and possible recovery to SC state when different square wave disturbances of length L in the range [0.01 m, 7 m] and duration τ in the range [1 ms, 100 ms] are applied to the superconducting cable. The computed minimum quench energy is shown to be typically above (in one case borderline to) the expected disturbance. The sensitivity to parametric variations of the heat transfer coefficient between strands and helium is significant for some disturbances. The inclusion of an external circuit in the model, providing selfconsistent boundary conditions, does not influence the results
CSNI validation matrix for the assessment of thermal-hydraulic codes for PWR LOCA and Transients
No full textAs Italian representative inside the thermal-hydraulic task group of Organization for Economic Cooperation and Development (OECD) / Nuclear Energy Agency (NEA) / Committee on the Safety of Nuclear Installations (CSNI), the current author contributed to a preliminary activity which ended up in an OECD publication. The framework of the activity is assessment and validation of system thermal-hydraulic codes.
Preliminary steps were taken to fix the requirements for the validation. Importance was given to the experimental data and to the scaling processes. The document evolved in about five years to the form a pillar document in the area of nuclear thermalhydraulics. Coauthors were top level researches and specialists working in the area at the time
- …
