RESISTANCE WELDING – PREFERRED TECHNIQUE FOR APPENDAGE WELDING IN PHWR FUEL MANUFACTURING
13th International Conference on CANDU Fuel - 2016 Aug. 15-18


Presented at:
13th International Conference on CANDU Fuel
2016 Aug. 15-18
Location:
Kingston, ON Canada
Session Title:
PLENARY SESSION (cont'd.)

Authors:
S.N.V. Kumar (Nuclear Fuel Complex, India)
S.K. Pathak (Nuclear Fuel Complex, India)
D.S. Setty (NUCLEAR FUEL COMPLEX)
G. Kalyanakrsihnan (Nuclear Fuel Complex, India)
N. Saibaba (NUCLEAR FUEL COMPLEX)
  

Abstract

Nuclear Fuel Complex (NFC) at Hyderabad is the sole fuel supplier for all the PHWRs and BWRs currently operating in India and is the world’s largest producer of nuclear fuel bundles of PHWR variety. Over a time period of a little more than four decades, NFC has evolved into an excellent manufacturing facility. One among many new techniques introduced at NFC, is Empty Tube Welding technique used for welding tiny Zircaloy appendages on the Zircaloy fuel tubes using resistance welding process. Using this technique, a towering average of about two lakh tubes per month are being appendage welded successfully. This could be achieved by deploying in-house developed-state-of-the-art appendage welding machines. Consistent quality is achieved by subjecting the product to rigorous testing & analysis and optimization of weld parameters. This is amply reflected in the fuel performance in the reactors. A comprehensive study on the robustness of resistance welding process employed for appendage welding has been carried out. Towards the same, test welds were prepared and subjected to additional tests like burst test, peel test, metallographic examination for weld microstructure and weld nugget size, heat affected zone and micro hardness measurements around the weld zone have also been carried out. These are in addition to the test for weld shear strength being carried out during regular production. The findings demonstrate the resistance welding process as a robust & and a highly reliable technique for appendage welding on Zircaloy fuel tubes. The paper describes the above findings in detail.

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