Search

For effective vacuum leak testing all cooling circuits serving the ITER vessel and in-vessel components shall be drained and dried so that after this procedure taking less than 100 h the purge gas passing through a component has water content less than 100 ppm. This process is four-stage, with the first stage using a short blast of compressed nitrogen to blow most of water in the coolant channels out of the circuit. This process is hindered by volumes which trap water due to gravity. To remove the trapped water, it is necessary, first, to heat up the structure by hot and compressed nitrogen, and then water is evaporated by depressurized nitrogen. The cooling system of the ITER Diagnostic Equatorial Port Plugs is of a complicated hydraulic configuration. The system branching might make difficult removal of water from the piping in the scheduled draining mode. The authors have proposed the KORSAR computation code to simulate draining of the GEPP cooling circuit. The numerical simulation performed has made it possible to describe the process dynamics during draining of the entire GEPP cooling circuit and to define the process time, amount and location of residual water and evolution of two-phase flow regime. [ABSTRACT FROM AUTHOR]

The superconducting magnets of the ITER are capable of accumulating up to 50 GJ. In case of coil quench the energy stored in the coils must be extracted rapidly. The problem can be solved by the Fast Discharge Resistors (FDR) under development at the Efremov Institute. The fast discharge of the coils results in practically adiabatic heating of the resistive elements up to 250 °C. The resistors should be cooled to their initial temperature within a reasonable time (4–6 h). With this in mind, the authors have designed the cooling system based on natural air circulation. When performing the numerical analysis of the cooling process, the authors have faced the problem of the essential non-uniformity of air flow distribution in parallel channels, which considerably increases the cooling time. Thus, while the cooling time does not exceed 3 h for a single FDR module, it exceeds 10 h for several modules. The numerical studies performed over the last few years have allowed the authors to propose a number of measures to optimize the air cooling system so as to mitigate the negative effect of the air flow non-uniformity in the FDR cooling system. [ABSTRACT FROM AUTHOR]

The ITER magnet system will operate in extremely severe conditions, which impose high requirements for mechanical and dielectric strength of the electrical insulation of the superconductive coils. Only monolithic structure obtained during the VPI procedure is capable to provide the required mechanical and dielectric strength for electrical insulation. To provide the qualitative insulation, a temperature non-uniformity of the electrical insulation should be kept within the range of [−5, +5 °C] and [−0, +20 °C] during filling with epoxy compound and its curing, respectively. The PF1 coil is about 150 t in weight and consists of materials with different thermal conductivity. Besides, a complicated geometry of the coil adds complexity to VPI. Since the VPI is usually a long-term and irreversible process (within pot life of compound), the whole process should be controllable. The paper describes the developed calculation model of the ITER PF1 coil and presents the results of numerical simulation of this model at VPI of electrical insulation. The completed VPI of the ITER PF1 coil has verified the proposed method for coil heating and proved an acceptable agreement between the calculated and measured temperature distributions throughout the VPI procedure. [ABSTRACT FROM AUTHOR]