Experiences in Manufacturing and Qualifying of Stainless Steel AISI 403 Grade Materials for PHWR Reactors of NPCIL

Abstract:

NPCIL uses stainless steel AISI 403 grade material extensively for very critical nuclear components. A very special application of this material is for manufacturing END FITTING BODY of COOLANT CHANNEL ASSEMBLIES of Pressurized Heavy Water Reactor (PHWR) of Nuclear Power Plants. Presently, two types of PHWR Nuclear Plants viz 220 MWe and 540 MWe are under operation in India. Next higher rating viz 700 MWe PHWR Nuclear Plants are at various stages of construction and due for commissioning in near future. There are number of Pressure Tubes in PHWR Nuclear Plants wherein fuel is loaded and are called coolant channel assemblies. End fitting bodies are assembled on either end of PRESSURE TUBES of coolant channel assembly. The Coolant (Heavy water) flows inside these assemblies and collects the heat produced during nuclear reaction in pressure tubes. This heat is utilized to produce Steam in Steam Generators. After giving up heat in Steam Generator, coolant returns to pressure tube and cycle continues. Material for End Fittings has been selected keeping in mind the mechanical properties at room and at elevated temperatures are compatible with mating component which are manufactured using Zircaloy and SS 410. It is also an essential that coefficient of thermal expansion is also compatible for mating material. Indigenization of the material for manufacturing of End Fittings with short delivery period has always been a challenge for commercial Nuclear Reactors. Inspection of these types of critical nuclear reactor components becomes critical due to the high safety standards and complexity in structures. There are very few manufacturers for this material in India. NPCIL took up a challenge for developing a new supplier in Northern Region of India for developing this material. A leading company in northern region of INDIA came forward and took up the challenge and succeeded for this venture. This paper deals with development of vender to manufacture of AISI 403 grade material by melting, refining ( ESR process), forging, heat treatment, testing & provide the guidelines to tackle the issue faced during this developmental work.

• Periodical: Advanced Materials Research (Volume 794)
• Pages: 194-200
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.794.194
• Online since: September 2013
• Authors: J.K. Jain, Sundar Singh, M.K. Mathur, N.P. Srivastava, K.P. Dwivedi
• Keywords: Ladle Refining Furnace, Nil Ductility Transition Temperature, Pressurized Heavy Water Reactor, Vacuum Carbon De Oxidation, Vacuum Oxygen Decarburization

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