The ITER toroidal field model coil project

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206 A. Ulbricht et al. / Fusion Engineering and Design 73 (2005) 189–327 Fig. 4.2. Second installation of the TFMC with the LCT coil for test Phase 2. The total weight including the lifting beam was 115 t therefore both cranes were used simultaneously. necessary for the installation into the vacuum vessel because of the small clearance between the LN2 shield and the test arrangement. All the connections of the He- and LN2-cooling system as well as for the current and measuring systems were manufactured now for both of the coils. All the tests mentioned below (Section 4.1.2) were performed successfully in advance and after the evacuation of the vacuum vessel and the start of the cool down. This was the installation of the largest test arrangement up to now into this facility. After completion of test Phase 2, the rig was again disconnected from the facility, extracted from the vacuum vessel and placed onto the assembly frame in the TOSKA experimental area. 4.1.2. Accompanying test strategy during installation The installation of large test arrangements requires a well-defined series of acceptance and accompanying tests. Acceptance tests are needed for unique transfer of responsibility and the reference state of the interfaces. Accompanying tests assure the quality of the installation work during the single steps and monitor the properties during test operation. During installation the accompanying tests are arranged in such a sequence that in case of faults a repair with a reasonable effort is possible. For the TFMC installation, these are mainly leak and pressure tests, instrumentation tests and tests of the dielectric insulation. In case of acceptance tests, geometrical and flow measurements are added. For the leak tests, the coolant circuit is pressurised to the maximum operation pressure. A bag made of a plastic foil or a temporary local vacuum chamber is then placed around weld seams or flange seals after completion of piping work. The volume of the bag must be small to obtain a high sensitivity in case of measurement of the leak according to the concentration increase method. The leak test by the local vacuum chamber has the same sensitivity as an overall vacuum leak test. The methods described above are indispensable as an accompanying test and for the localisation of leaks. The last and most reliable leak test is performed with the coil in the vacuum vessel at a pressure level
A. Ulbricht et al. / Fusion Engineering and Design 73 (2005) 189–327 207 Table 4.1 Overview of performed acceptance test and accompanying test during installation Step Leak test Sensor continuity Dielectric insulation test Mechan. dimensions After assembly TFMC/ICS/Aux. structure + a + + + − After installation in the TOSKA vac. vessel + a,b + + − + After evacuation of the TOSKA vac. vessel + c + + − − Fault localisation work + a,b + + − − After cool down, acceptance test + c + + − + Before warm up + c + + − + After warm up at room temperature + c + + − + Fault localisation work + a,b + + − − a Bagging and concentration increase. b Local vacuum chamber. c Vacuum leak test. 4.2. Test procedure The test procedure is the agreed sequence of test steps to achieve the desired results in an optimised way in time and risk. The test procedure of the single coil is given in [49]. The test procedure for the TFMC test in the background field of the LCT coil was determined by the following boundary conditions: (1) each coil has to be operated first as a single coil; (2) for currents > 12 kA the LCT coil has to be operated at 3.5 K, which is a more sophisticated operation mode of the cryogenic system (Section 4.3.2.2). The single steps of the summarised test procedure of Phase 2 are presented in Table 4.3 [49]. The test procedure is characterised by defined cool down, cooling and ramping procedures to certain current levels. According to the FEM analysis performed by the coil manufacturer AGAN, the TFMC current has to be limited to 70 kA in order to avoid overstressing of the outer joint region. The FEM analysis showed that a current combination (TFMC 80 kA, LCT 14 kA) had nearly the same attractive forces between the coils but increased the Lorentz body (volume) force on the Table 4.2 Measured overall helium leak tightness in test Phase 1/2 by performing a vacuum leak test Test phase Helium leak rate [mbar l/s] (pressure [barabs.]) Flow test TFMC conductor. The assessment of the measured mechanical data and the upscaling to a current combination (TFMC 80 kA, LCT 16 kA) should create no mechanical problem, which was confirmed in the experiment. In this case, the achieved load is 100% of the peak Lorentz body force (∼800 kN/m) expected on the ITER TF coil conductor in nominal operating conditions. The fast high voltage discharge test was cancelled in Phase 1 after the discovery of the insulation fault. The careful dielectric investigations at the end of Phase 1 and their assessments have shown that a fast high voltage discharge with reversed polarity and a reduced voltage (≤4 kV) can be performed without risk. All tests of the procedure were performed successfully in the given time frame of about 4.5 months. 4.3. Cryogenic system and operation experience A 2 kW He refrigerator was used for cool down of the test configuration, steady state operation at 4.5 K and for the cooling of the four current leads (Fig. 4.3)in both of the tests phases [48,50]. An additional available 500 W refrigerator, which is designed for an operation temperature between 4.5 und 1.8 K, was used for Before cool down (300 K) After cool down (4.5 K) Before warm up (4.5 K) After warm up (300 K) Phase 1 1 × 10−7 (21) 2 × 10−5 (3.5) 2 × 10−5 (4) 1 × 10−7 (21) Phase 2 5 × 10−7 (8) 7 × 10−7 (4.8) 3 × 10−4 (3) 1 × 10−6 (18)
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Page 3 and 4: The application and continuation of
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the outer joint outlet. This heat e
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Fig. 6.9. Loss energy of the TFMC w
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Fig. 6.13. Evolution of the couplin
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and during Phase 2 (within 6%). The
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other hand, if using the central ch
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Fig. 6.20. Top: quench propagation
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Fig. 6.23. Measured (multi star) an
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fB Friction factor of the bundle re
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surement with voltage taps located
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Table 7.3 TFMC pancake (joint) resi
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Table 7.8 Values of TFMC and FSJS j
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Fig. 7.7. The insulated bus bar typ
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Rneg, 1[nΩ] = 1.77 [n�] + 3.75
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law actually is good (better than
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Fig. 7.16. Current in the petals re
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ence may exceed the inaccuracy of t
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provided support to the coil and th
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(c) The best fit in relation to the
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8.5. Comparison to ITER TF coil str
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Fig. 9.7. Partial discharge activit
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circular cross-section and central
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two different sets of Hall probe ar
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equation: dx = Ax + Bu dt y = Cx +
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[34] E. Salpietro, R. Maix, G. Bevi
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[86] R. Heller, D. Ciazynski, J.L.
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ple for ITER, IEEE Trans. Appl. Sup
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PSB: Power System Blockset is a MAT
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The ITER toroidal field model coil project

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