For most nuclear design and in-service inspection codes, fracture mechanics is used to evaluate the integrity of cracked components. The major parameters used in this kind of analysis are K and J which are used to estimate the crack-tip driving force. Different nuclear codes (e.g. RSE-M appendix 5 , AFCEN code: RCC-MRx appendix A16 , R6 rule , ASME B&PV Code Section XI , API 579 ) propose more or less sophisticated analytical solutions to estimate K and J. The solutions are based on compendia of stress intensity factors and limit loads that have been developed for common component geometries, type of defects and loading conditions. These codes also propose very different methods to incorporate the effects of thermal loads on K and J and to analyse cracks in a weld joint.