Page 55


ORNL-DWG 71-43138


D I (in.) 0.245 KW 149.58 INLET PRESSURE 3800.00 DO (in.) 0.375 WF 4812.00 PRESSURE DROP 101.06 DII (in.) 0.495 WS 802.00 ELEMENTLENGTH (ft) 1.00 DIO (in.) 0.625 N B 2 DATE 8-30-71

1 200 1100


-P 900 g aoo


3 I a-






-1 J





100 0




a 50 400

300 0








0 35


Fig. 3.4. Tube-in-tube molten-salt steam generator test section.


A. N. Smith



The as-removed appearance of the PKP pump rotary element and the appearance of certain other test loop components were described in the previous report. During this period, the pump rotary element was dismantled, and the component parts were examined visually after washing with hot water. Except for the inner heat baffle plates, the appearance of the Inconel metal surfaces was such as to imply insignificant attack during the fluoroborate service. The inner heat baffle plates were badly corroded, and their condition was attributed to corrosive material produced by the reaction of moisture in the incoming purge gas with puddles of salt which were left on the baffle plates during the ingassing transients in May and June 1968. More detailed information on observations and conclusions resulting from examination of the rotary element parts is presented below. No further work is planned on this test program. A report9 is being prepared summarizing the work on the sodium fluoroborate test loop.

3.5.1 Inspection of PKP Pump Rotary Element

The impeller and upper impeller housing (see Fig. 3.5) were removed from the PKP pump rotary element, and the upper labyrinth seal ring and the heat baffles were removed from the impeller housing. All parts were then examined visually after washing with hot water to remove residual deposits of NaBF4 salt. The following is a summary of our findings. 1. The vanes on the back side of the impeller and the grooves inside the upper labyrinth seal ring showed little sign of wear, based on the appearance of sharp edges and corners. 2. The diameter of the slinger ring appeared to match the curvature of the high-nickel, gray-black lumps previously described.’O 3. The appearance of the inner heat baffle plates was markedly different from that of the outer heat baffle plates. Except for a slight blackening of the surfaces, the outer plates suffered very little attack. On the other hand, the inner baffle plates (see Fig. 3.6) had been severely attacked as evidenced by holes completely through io some places and by severe pitting in other places. The attack was not homogeneous on any one plate or from one plate to another. The top surface of the top plate was severely pitted, but the other surfaces which combined to form the chamber above the top plate (shaft, inner surface of impeller housing support cylinder, and lower surface of the cooling oil chamber) were relatively free of attack. All baffle plates except the one below the top plate had holes corroded completely through. The inner heat baffles fitted very tightly against the inner surface of the upper impeller housing support cylinder, so that probably most of the gas flow was past the inner annulus between the baffle plates and the pump shaft. 4. A groove was found in the surface of the pump shaft at a point adjacent to the inner heat baffles. The groove was about ‘4 in. ’wide and about ‘4 in. in maximum depth. It was smooth in contour and was not pitted. 5 . Metal surfaces had a coarse, grainy appearance but were not severely pitted except on the inner heat baffle plates. 6. Contrary to pump assembly drawing F-2882-K, there were no holes in the impeller housing support cylinder just above the inner heat baffles. The absence

9. A. N. Smith, Experience with Fluoroborate Circulation in an MSRE-ScaleLoop, ORNL-TM-3344(to be published). 10. MSR Program Semiannu. Progr. Rep. Feb. 28, 1971, ORNL-4676, p. 55.