The fitness for service of the facilities of operational nuclear power plants is secured by proper inspections and evaluations. Defects took place in components will be detected by periodical inservice inspection, and fitness for service of cracked components during an evaluation period is evaluated. Although variation exists in the conditions used for inspection or evaluation, it is difficult to grasp about those influences on the reliability of cracked components by the deterministic evaluation like Fitness-for-Service Codes. In this study, influences of inspection parameters (defect sizing error, percentage of defect oversight, detectable defect size, successive tests) and an evaluation parameter (crack growth rate) on failure probability were evaluated for primary loop recirculation system piping of boiling water reactors in which many stress corrosion cracks took place. From these evaluations, the dominant parameters for the reliability of piping having stress corrosion cracks were clarified, and the requirements for the inspection and evaluation for revising Fitness-for-Service Codes were proposed.