DESIGN AND OPERATION OF A FORCSE-CIRCULATION CORROSION TEST FACILITY (MSR-FCL-l) EMPLOYING HASTELLOY N ALLOY AND SODIUM FLUOROBORATE SALT

摘要

A forced-circulation loop (MST<-FCL-l) was assembled and operated to evaluate the compatibility bf standard 'Hastelloy N with' sodium fluoroborate—oodium fluoride eutectic (NaBF4—8 mole% NaF) coolant salt at operating conditions expected in the Molten-Salt Reactor Experiment coolant circuit. The "salt velocity in l/2-in.-OD, O.0^2rin.-wall tubing was nominally 10 fps. Hastelloy N corrosion specimens were exposed to the circulating salt at temperatures of 950 1030, and 1090°F. The test has operated more than 10,000 hr at these conditions and tests are continuing. This report, is mainly concerned with the design, fabrication, and operation of the facility. . Special problems related to accomodating the BF3. vapor, pressure of the salt were resolved, and the sodium flubroborate demonstrated heat transfer characteristics that could be approximated by conventional correlations such as the Dittus Boelter equation. Corrosion rates generally decreased with operating time;for example, the lowest, corrosion rate ob served for the 1090°F corrosion specimens during a 2900-hr test interval was equivalent to 0.000.3 in. of uniform material" removal per year.