Technical Challenges of Retubing the E´lectricite´ de France (EDF) Belleville Unit 2

This paper describes the numerous challenges involved in the partial retubing of the Belleville Nuclear Station Unit 2 steam surface condenser using 64,242 tubes. Specific challenges of the project included retubing with both duplex stainless steel tubes and with brass alloy tubes, analyzing the risk of flow induced tube vibration and designing a staking system to prevent such vibration, and, replacement of six tubesheets. The tubesheet stresses were analyzed using a beam strip analysis and ANSYS, and new tubesheets were reverse engineered from original drawings. Tubesheets were aligned to the support plate holes using a newly developed laser alignment system. Prior to the retubing, extensive mockup tests were performed to optimize the rolling torque, and to determine rolling parameters that limit the work-hardening of the brass tubes. Testing also included leak testing the mockup joints with a small pressure vessel and then performing a helium leak test of the pressurized tube joints. Tests were performed with both smooth and serrated holes.