Study of temperature profile in nuclear fuel element end cap resistance upset welding using analytical technique

The temperature distribution in solid-state end cap welding process is predicted using analytical heat transfer study and the results are verified using thermal imaging technique. The predicted and actual temperature rise with welding time showed similar trends. The temperature rise occurs at much faster rate in the initial phase due to high initial contact resistance between cladding tube and end cap. The peak temperature in the welding process for the current ranges of welding variables reaches around 850°C-900°C under normal operating conditions, which supports the presence of Widmanstaetten or martensitic structures at the heat affected zones in end cap welding. However, more accurate measurements of the temperature are possible in future with the use of photo-sensors with very low response time. (author)