A. Sagara

H. Hashizume

K. Kitago

S. Ito

S. Kitajima

Y. Usui

Hashizume,  H.

Kitajima,  S.

Ito,  S.

Usui,  Y.

Kitago,  K.

Sagara,  A.

NIFS-Repository (National Institute for Fusion Science)

§4. New Reactor Concept Using Remountable SC Magnet and Liquid Blanket Hashizume, H., Kitajima, S., Ito, S., Usui, Y., Kitago, K. (Quantum Sci. & Energy Eng., Tohoku Univ.), Sagara, A. The concept is that the first wall is made from three layers, where the liquid layer is sandwiched by two solid metal thin plates. This aggressive design owes to the remountable HT c SC(superconducting) magnet using direct mechanical jointing method, which means we can easily access to the reactor component like the first wall [1]. Figure 1 shows the concept of remountable first wall, which is divided into upper and lower parts. The end of each part is welded to the main structure, while the ribs are not welded .. We chose 0.2m as the channel width, 5mm as the thickness of the solid metal thin plate and 2.5mm as half of the rib thickness from the view point of heat removal capacity and structural integrity [2]. The solid metal plates except the back wall are made of HT -9. Since the thickness of back wall is not determined, we assume that the thickness is 5 mm with half of electrical conductivity of HT -9. Flibe is chosen as one of the coolant material to reduce the WID pressure drop since the large inner pressure of coolant is not allowable from the view point of structural integrity in the present concept. Liquid lithium is also chosen, which is widely proposed as the coolant material. The channel is coated in two ways as follows. The channel is coated with insulator on the surface of ribs, which can be available when we use the remountable first wall. This system can make the coating and maintenance processes simple since the back wall can be detached from the first wall. In the second way, the three surfaces of channel are coated as usually done in conventional design. The velocity profiles are assumed to be fully-developed, and then 2-dimensional system of equations was solved using the finite element. Since the coolant pressure is assumed almost 200 kPa and the margin to the allowable pressure from the atmospheric pressure is about 70 kPa, the maximum velocity was evaluated 2 mlsec in case of flibe without the WID effect [2]. In order to take this effect into account, we chose 1.25m1sec for the flibe velocity, which needs 15kPa pressure difference due to pipe friction [2]. The heat flux on the first wall is assumed to be 0.6 MW/m2. In case of lithium, the required velocity for the heat removal is evaluated to be 0.15 mis, where the temperature rise is about 120 K and the pipe friction becomes negligibly small .. If the radius of curvature of first wall, R in Fig.l , is assumed 3.8 m, the length of the channel of first wall facing to the plasma becomes 12 m and then the length of channel is assumed to be 15 m including inlet and outlet piping. Therefore the pressure gradient should be less than 3.6 kPa/m when the WID pressure drop along this channel becomes less than 55 kPa to make the total pressure drop less than 70 kPa. Using the 268 flibe as coolant material under 6 T field, it is necessary to be coated with the insulator whose electric conductivity ratio (a coating I a HT-9) is about 10-6. The MHD pressur~ gradient of lithium to flow with the average velocity of 0.15 mls is calculated to be 127 kPaim without any coating, which means that the channel will yield. In this case, we can also reduce the WID pressure drop to 15 kPa (0.99 kPalm) using the whole rib coating by the same insulator used for the flibe coolant system. References [1] S.Ito et.al, , 10th Int. Symposium on Applied Electromagnetics and Mechanics, (2001) p.283-284. [2] H.Hashizume et.al "Advanced Fusion Design using Remountable HTc S.c. Magnet" , Joint Conference of 12th International Toki Conference on Plasma · Physics and Controlled Nuclear, Toki (2001). Welding First wall Remountable SC magnet / Fig.1 Remountable first wall with remountable SC magnet Fig.2 Velocity profile for Flibe ().a. ~ 004 ~ 0.\l3 O.a. ~ ~ ~ o~ 003 u Q.oa ~ .Q ~ 002 ~ O.l)l ~ ~ IS 001 Q.l)l .Q ~ 

New Reactor Concept Using Remountable SC Magnet and Liquid Blanket

New Reactor Concept Using Remountable SC Magnet and Liquid Blanket

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