Abstract
A /sup 7/Be transport test was performed in the Beryllium-7 Experimental Lithium Loop with hot leg at 270/sup 0/C and cold leg at 230/sup 0/C. The ''cold leg'' test stringer was in a rising temperature region at 250/sup 0/C. A total of 108 test coupons were included in the material compatibility and deposition test programs, containing AISI Types 304 and 304L stainless steels, Fe-2 1/4 Cr1 MO, pure iron, molybdenum, beryllium, zirconium, titanium, yttrium, three different aluminide coatings on Type 304 stainless steel substrates, and both tubular and flat butt-welds of Type 304 stainless steel. An average lithium velocity of 1.36 m/s was established during the test which was terminated after 3718 h. The /sup 7/Be activity data indicated that the deposition of /sup 7/Be is a function of temperature. The cold leg positions displayed maximum /sup 7/Be deposition followed by the intermediate temperature locations (cold leg test stringer) and the hot leg locations. Two chemical forms of /sup 7/Be are expected in lithium, namely, unbonded /sup 7/Be at a low concentration, and a fine precipitate of /sup 7/Be/sub 3/N/sub 2/ at a high concentration. The deposit in the hot leg region is presumed to be primarily /sup 7/Be, whilemore » the cold leg deposit is mostly /sup 7/Be/sub 3/N/sub 2/. The cold leg specimens of a given material showed more /sup 7/Be deposition than the hot leg specimens of the same material, consistent with the /sup 7/Be activity data on the piping. Based on the present investigations and previous data, it is concluded that /sup 7/Be produced in the Fusion Materials Irradiation Test (FMIT) facility will have sufficient nitrogen in the lithium system to form /sup 7/Be/sub 3/N/sub 2/. It is expected that the majority of /sup 7/Be will be transported to the colder parts of the loop and deposited as /sup 7/Be/sub 3/N/sub 2/. However, a small amount of /sup 7/Be in the unbonded form will be in the hotter parts of the loop and is expected to diffuse into the steel piping.« less
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