Slow strain rate tensile (SSRT) tests have been performed on hollowed cylindrical specimens of 316 stainless steel in a simulated pressure water reactor (PWR) environment.The effects of dissolved hydrogen (DH) in the environment and surface finish condition of an inner surface of the hollowed specimen on stress corrosion crack (SCC) initiation and small crack growth behavior of 316 stainless steel were investigated in PWR primary water at 325 ℃ with various DH levels of 5, 15, 30 and 50 cc (STP) H2/kg H2O.SCC initiation and small crack growth behavior of specimens with inner surface finish bya drilling and honing showed a similar trendin the water chemistry with different DH levels.Drill finished surfaces have higher hardness than those of honed surface which was more detrimental in SCC initiation and propagation at a fix hydrogen level.Most of the tests were interrupted at the maximum load to avoid a final failure to observe the small crack growth behavior as well as crack initiation behavior.The elongation to the maximum load of the specimen at 50 cc (STP) H2/kg H2O is the largest, and that at 15 cc (STP) H2/kg H2O is the smallest.Fractographic examinations on the failed samples showed mixed modes of transgranular and intergranular cracking.The cracks seemtransgranular at the initial stage and then change to intergranular.Many cracks were observed along the gauge length of the specimens.The crack depth and crack numbers were measured by the cross sectional inspections on four different planes along the gauge length by optical microscope (OM) and scaning electron microscopy (SEM) and collected.The statistical results show that the depth of most of the cracks was less than 5 μm.The average crack growth rate (CGR) of the specimen tested at a DH level of 15 cc/kg was the highest.The maximium CGRs calculated from the maximum crack length and the testing time of drill finished specimen is higher than those of hone finished specimen in all DH levels.The total crack numbers for the honed specimens are less than those of drilled specimens.This means that the propensity of crack initiation is higher in drilling specimens than honed specimens.The oxide films formed on the inner surface of 316 stainless steel tube specimens show a multilayer structure.The outer layer is large polyhedral crystalline particles, and the inner layer is fine compact crystalline oxides.The oxide films became thicker with the DH increasing level.The oxide films were investigated before and after polishing layer by layer by Raman spectroscopy.The Rarnan results showed that the oxide film formed on 316 SS in primary PWR water consist of outer layer of Fe3O4, and inner layer of spinel (FeCr2O4 or NiFe2O4).The influence of DH on the oxidation and SCC behaviors are also discussed.