Application Case of RCC-MRX 2012 Code in Significant Creep

This paper gives an application case of the RCC-MRx mechanical design code for nuclear components in the domain of significant creep. It could be seen as a guide for engineers who have to perform mechanical creep and creep-fatigue analyses with this code. The application case is a spherical shell with an internal radius of 1250 mm and a thickness of 50 mm, which is made in AISI 316L. The structure is assembled by manual arc welding of plates using 19Cr-12Ni-2Mo type rods. The shell is intended to operate at 550°C mean temperature under an internal pressure of 5 MPa due to argon gas (the atmospheric pressure is considered outside). During operating, the internal temperature is equal to 600°C and the external temperature is 500°C. The shell is periodically stopped for servicing: during these periods, the temperature is 50°C and uniform, and the internal pressure is equal to the atmospheric pressure. A cycle is defined by a 500 h dwell time at 550°C followed by a 24 h arrest at 50°C; transient temperatures, thermal shocks during starting and arrest are neglected. The application of the RCC-MRx is shown for different damages, such as:- Excessive strain, plastic instability and rupture for primary loadings (negligible and significant creep);- Ratcheting, fatigue, creep-fatigue for all type of loadings.The effect of welds on expected life (creep, fatigue), and the comparison of calculated lives and allowed operating cycles for 316L and 316LN are described.Copyright © 2014 by ASME