ICP-MS measurement of silver diffusion coefficient in graphite IG-110 between 1048K and 1284K

Abstract Silver-110m has been shown to permeate intact silicon carbide and pyrolytic carbon coating layers of the TRISO fuel particles during normal High Temperature Gas-Cooled Reactor (HTGR) operational conditions. The diffusion coefficients for silver in graphite IG-110 measured using a release method designed to simulate HTGR conditions of high temperature and flowing helium in the temperature range 1048–1253 K are reported. The measurements were made using spheres milled from IG-110 graphite that were infused with silver using a pressure vessel technique. The Ag diffusion was measured using a time release technique with an ICP-MS instrument for detection. The results of this work are: D Ag , IG − 110 = ( 6.6 × 10 − 4 m 2 s ) exp ( − 1.74 × 10 5 J mol R T ) The measured activation energy of 174 kJ/mol compares well with the range of values [154–193 kJ/mol] reported in the literature for LTI pyrocarbon. The measured pre-exponential D0 value of 6.60 × 10−4 m2/s is similar to the value of 5.3 × 10−4 m2/s reported for Russian LTI pyrocarbon.