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32 Table 3.2. Results of calculations for test sections operating with salt and feedwater velocities at 20 fps Test section number OD of inner tube, in. ID of inner tube, in. Wall thickness of inner tube, in. OD of outer tube, in. ID of outer tube, in. Wall thickness of outer tube, in. Inlet feedwater temperature, "F Outlet steam temperature, OF Salt outlet temperature, O F Salt inlet temperature, OF Maximum temp drop across inner tube wall, O F Inner tube wall temp at maximum ATW Feedwater flow rate, lb/hr Salt flow rate, Ib/hr Maximum allowable working pressure for inner tube at 1100째F Water/steam pressure drop, psi Tube or test section length, ft Total heat transferred, kW Heat transferred to point of max temp drop across inner tube wall, kW Distance from inlet to position of maximum tube wall AT, ft

1.20.1 0.250 0.152 0.049 0.375 0.319 0.028 700 1001.6 850 1144.1 132.9 798.0 309.0 1854.0

2.20.1 0.375 0.245 0.065 0.625 0.495 0.065 700 1008.9 850 1145.8 146.3 796.0 802.0 4812.0

3.20.1 0.500 0.334 0.083 0.750 0.666 0.049 700 1001.4 850 1143.1 158.4 790.4 1491.2 8944.2

4.20.1 0.625 0.407 0.109 1.000 0.810 0.095 700 1002.1 850 1142.4 174.4 787.9 2214.8 13,288.8

5.20.1 0.750 0.5 10 0.120 1.125 0.995 0.065 700 1002.1 850 1141.6 176.6 787.4 3483.0 20,898.0

6.20.1 0.875 0.579 0.148 1.250 1.152 0.049 700 1002.2 850 1140.6 185.3 787.4 4488.6 26,931.6

7.20.1 1.000 0.640 0.180 1.500 1.310 0.095 700 1002.2 850 1139.4 191.9 187.8 5469.8 32,818.8

4097 73.0 16 56.1

3725 95.6 33 146.5

3600 109.9 53 270.0

3743 128.6 76 400.2

3611 144.9 106 627.9

3654 164.2 139 806.7

3920 187.4 176 980.5

28.5

81.5

141.0

212.0

336.7

442.6

$72.4

8

17

28

41

58

78

10 1

of these holes means that all of the pump shaft purge gas had to flow past the five inner heat baffle plates in

order to get to the main part of the pump bowl. We have drawn the following conclusions from these observations: 1. Except for the inner heat baffles, corrosive and erosive attack was slight, which is consistent with observations made of pump bowl surfaces.l0 2. The high-nickel, gray-black lumps were formed by deposition on the surface of the slinger ring, probably by precipitation of corrosion products on the cooler shaft surface as was discussed earlier.'O 3. The severe heterogeneous attack suffered by the inner heat baffles came about in the following manner. NaBF4 salt was forced into the baffle region during the ingassing transients in May and June 1968.' Scattered puddles of salt were retained on the baffle surfaces because the latter were not perfectly flat. The incoming

11. MSR Program Semiannu. Rogr. Rep. Aug. 31. 1968, ORNL-4344, pp. 76-77.

purge gas was in intimate contact with the puddles of salt, and the moisture in the purge gas, estimated to have been somewhere between 1 and 20 ppm by volume, combined with the puddles of salt to form reaction products which corroded the adjacent metal surfaces. 4. The degree of attack on the upper baffle plates was at least as severe as that on the lower baffle plates. If we assume a significant temperature gradient between the bottom and top plates, the implication would be that the water-salt reaction products are highly corre sive even at relatively low temperatures. Direct measurements of the baffle plate temperatures were not made, but it is estimated that the temperature of the top baffle plate was 500째F or less. Additional tests are needed to determine the variation of corrosiveness with temperature, since there are important general implications for reactor systems using NaF3F4. For example, efficient cleaning procedures will be needed to ensure that N&F4 salt residues are not left on the outside surfaces of pipes and equipment where exposure to moist atmospheres is probable, and where the metal

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ORNL-4728  

http://www.energyfromthorium.com/pdf/ORNL-4728.pdf

ORNL-4728  

http://www.energyfromthorium.com/pdf/ORNL-4728.pdf

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