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chromium concentration values are lower than their solubility values at 530ºC (30 212 and 13.8 ppm<br />

respectively).<br />

After the end of the tests, the loop was cut to be destructively examined. The structural austenitic<br />

steel presented material solution, especially at the hottest areas. Figure 10 shows a cut of the coldest<br />

area of the loop in which particle deposition was observed. This deposition was also detected at the<br />

upper corner of the cold leg. Two different kinds of particles were identified. The round particles<br />

closer to the steel wall are formed by chromium, iron and oxygen and the particles with geometrical<br />

shape are an intermetallic compound of nickel and bismuth.<br />

Figure 10. Slags deposition detected in the cold leg loop<br />

Cold leg<br />

Ar + O 2<br />

Cold leg<br />

Hot leg<br />

Hot leg<br />

Wall loop, 316L SS<br />

Samples of solidified lead–bismuth from the hot and cold zones were taken to measure oxygen by<br />

LECO. A heterogeneous oxygen distribution was observed in the samples. At the core, 2 ppm oxygen<br />

were observed in the hot zone, and 1 ppm oxygen in the cold zone. Near the walls, 9 ppm oxygen were<br />

measured in the hot zone and 6 ppm oxygen in the cold zone.<br />

4. Discussion<br />

Liquid metal corrosion depends on the solution rate and the solubility value of the solid metal in<br />

the liquid metal. Lead alloys, and in particular lead-bismuth eutectic, show a higher agressivity to the<br />

structural materials than the alkali liquid metals. In a static system, solution of the solid metal occurs<br />

until the solubility value of the main elements of the alloy is reached. In a dynamic system with<br />

temperature gradient, a mass transfer process occurs. The dissolved material at the hot zone is<br />

405

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