page 1 of 12 Design of a low pressure drop liquid metal cooling system M. S. Tillack with advice and assistance from X. R. Wang, S. Malang and others ARIES Project Meeting October 2011

page 2 of 12 Why do we need this? 1.Complex liquid metal cooling circuits have large, uncertain effects on power core performance. 2.Past estimates of flow distribution as well as pressure drop did not properly account for 3D effects, which MHD experts consider dominant in insulated channel designs. 3.Some sacrifice in performance will allow more conservative ( i.e., credible) treatment of the uncertainties in MHD behavior. 4.Layout of the flow circuits is important because it affects the power core configuration and space constraints. 5.R&D efforts are being wasted (in my opinion) studying “lousy designs”.

page 3 of 12 To keep 3d effects low, maintain constant GoodBad Ugly B B ARIES-AT

page 4 of 12 Apply these principles to all flow paths inside B 180˚ bends Expansion Flow split, distribute, merge, collect ManifoldField entry/exit

page 5 of 12 (1) 180˚ bend Parallel flow is easy to avoid. Side walls need special treatment. One of two segments in the OB blanket

page 6 of 12 Forces in the bend are dominated by inertia (calculations for a single 1.4×6 cm FW channel) 2D MHD inerti a F = 0.2 N F = 20 N (~4 lb f )  10250kg/m 3  7.60E+05  -m  6.5E-04kg/(m s) v 4m/s b 0.004m a 0.014m A 56E-06m2m2 L m B 8T Ha 3830 (dissipative)(non-dissipative) Will inertial forces determine flow distribution? o In this 2d case: yes o In a 3d flow scenario: Depends on 3d currents

page 7 of 12 (2) Flow distribution with 2D expansion Expansion perpendicular to B has minimal 3d effects Flow at an angle to B is allowed if v perp is unchanged

page 8 of 12 (3) Bundling of pipes into access pipes All of the ducts fit in a small access pipe “enclosure”. The main issue here is cutting/welding or flange connections.

page 9 of 12 In-field combining is possible, but tricky Probably OKProbably not OK Not clear this is desirable; entrance/exit effects will be exacerbated

page 10 of 12 (4) Minimization of entrance/exit effects Multiple small channels have smaller 3D currents than one large channel. Proposed this at previous meeting; Later confirmed advantage in discussions with UCLA. Need to avoid introducing new problems, and need experimental and computational verification. Already exploited in the proposed new design with segmented access pipes.

page 11 of 12 (5) Flow manifolds outside the field No MHD effects – ordinary manifolds are allowed. Stack 3 blanket circuits toroidally (IB, OB1 and OB2). Different toroidal locations for two blanket “segments”. Single segment of one circuit Ring header Analogous to “old design”

page 12 of 12 Summary of flow path design features Cool both divertor and HT shield with He, removing most of the flow path complexity already. Perform all complex flow combining outside the field. Place flow distribution network at power core bottom. Entrance/exit effects are reduced due to smaller channel size. 180˚ bends with provisions to prevent parallel flow. The new design has minimal 3D effects, and very low  p

page 13 of 12 Backup

page 14 of 12 Coolant circuits 1, 2, and 4 in ARIES-AT 124