Aerosol behavior tests are being conducted in WIND project at JAERI to investigate FP aerosol behaviors in piping of a reactor coolant system. Cesium iodide (CSI) was supplied into a test section made of a straight stainless steel pipe. It was identified that the deposition of CSI was remarkable within a part where the temperature of the carrier gas was higher than that of the test section wall. Dominant deposition mechanisms were supposed to be vapor condensation and thermophoretic aerosol deposition. In cases that argon as a carrier gas was used with a lower Re number, the deposition of a larger amount of CSI was found on the ceiling surface than the side wall and floor surfaces of the test section. On the contrary, an uniformly distributed deposition of CSI over the circumference of a flow area cross-section was observed in a test with a higher Re number. A considerable deposition onto a floor surface of the test section was confirmed when a mixture of argon and steam was applied as a carrier gas. A scanning electron microscope (SEM) observation showed larger particles were deposited onto the floor, comparing with cases of an argon carrier gas.
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