Wastage properties of high-chrome steels as heat transfer tube material for steam generator; Small leak wastage tests

not registered; not registered; Himeno, Yoshiaki

From an economical point of view, a unit-type steam generator is being considered as the most promising one for a demonstration FBR. Material nominated for the heat transfer tubes of that type steam generator is such high chrome ferritic steels as 9Cr type steal. However, wastage data of the FBR steam generator are insufficient for high chrome steels, so that it is necessary to construct wastage database for selecting a tube material for the unit type steam generator. Therefore, small leak wastage tests were conducted for Mod.9Cr-1Mo, 9Cr-2Mo, and 9Cr-1Mo-Nb-V steels in SWAT-2 Test Loop. In the tests, (a)water leak rate, (b)leak nozzle to target distance, and (c)sodium temperature, were varied as empirical parameters. Test results are as follows: (1)There are not large differences in the resistivity to the wastage among the three 9Cr materials. (2)The high-chrome steels are twice more wastage-resistant than the 2.25Cr-1Mo steel. (3)Wastage rates of the high-chrome steels are about the same as those of austenitic stainless steels at the water leak rate below 0.5g/s. (4)A common empirical formula of the wastage rate is obtained for the three materials; Mod.9Cr-1Mo, 9Cr-2Mo and 9Cr-1Mo-Nb-V steels.