In situ measurement of tritium permeation through stainless steel

The TMIST-2 irradiation experiment was conducted in the Advanced Test Reactor at Idaho National Laboratory to evaluate tritium permeation through Type 316 stainless steel (316 SS). The interior of a 316 SS seamless tube specimen was exposed to a He-4 carrier gas mixed with a specified quantity of tritium (T-2) to yield partial pressures of 0.1, 5, and 50 Pa at 292 degrees C and 330 degrees C. In situ tritium permeation measurements were made by passing a He-Ne sweep gas over the outer surface of the specimen to carry the permeated tritium to a bubbler column for liquid scintillation counting. Results from in situ permeation measurements were compared with predictions based on an ex-reactor permeation correlation in the literature. In situ permeation data were also used to derive an in-reactor permeation correlation as a function of temperature and pressure over the ranges considered in this study. In addition, the triton recoil contribution to tritium permeation, which results from the transmutation of He-3 to T, was also evaluated by introducing a He-4 carrier gas mixed with He-3 at a partial pressure of 1013 Pa at 330 degrees C. Less than 3% of the tritium resulting from He-3 transmutation contributed to tritium permeation. (C) 2013 Elsevier B.V. All rights reserved.