b'Figure 2. Transverse metallography ofthus the annulus was fully closed.along the fuel-cladding interface the FAST-008 pin across the centerLastly, the FCMI behavior of the pinregion while leaving a thin layer of of the pin. The redistribution withinwas appreciably different to that offuel adhered to the cladding. This this pin, which is a conventional solid pin, is notably different thanhistoric pins where the profilometrysuggests that during cooldown the that of FAST-007 which is an annulardata revealed approximately zerofuel may have thermally contracted, geometry. This pin also showsstrain across the fuel region. Theand the tension of the contraction similar tearing to that of FAST-007 radiography images provide an indi- was sufficient enough to pull the cation of the cladding constrictingcladding inward and eventually across the fuel region. The opticalfracture the fuel. This will be the graphs provide some confirmationsubject of modelling exercises in the of this as the fuel appears to fracturefollowing year.162 2023|AFC ACCOMPLISHMENTS'